xref: /freebsd/contrib/llvm-project/clang/lib/Sema/SemaCast.cpp (revision 06690044dac183ea1d93c2ae227e261da3bdca2a)
1  //===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===//
2  //
3  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4  // See https://llvm.org/LICENSE.txt for license information.
5  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6  //
7  //===----------------------------------------------------------------------===//
8  //
9  //  This file implements semantic analysis for cast expressions, including
10  //  1) C-style casts like '(int) x'
11  //  2) C++ functional casts like 'int(x)'
12  //  3) C++ named casts like 'static_cast<int>(x)'
13  //
14  //===----------------------------------------------------------------------===//
15  
16  #include "clang/AST/ASTContext.h"
17  #include "clang/AST/ASTStructuralEquivalence.h"
18  #include "clang/AST/CXXInheritance.h"
19  #include "clang/AST/ExprCXX.h"
20  #include "clang/AST/ExprObjC.h"
21  #include "clang/AST/RecordLayout.h"
22  #include "clang/Basic/PartialDiagnostic.h"
23  #include "clang/Basic/TargetInfo.h"
24  #include "clang/Lex/Preprocessor.h"
25  #include "clang/Sema/Initialization.h"
26  #include "clang/Sema/SemaInternal.h"
27  #include "clang/Sema/SemaObjC.h"
28  #include "clang/Sema/SemaRISCV.h"
29  #include "llvm/ADT/SmallVector.h"
30  #include "llvm/ADT/StringExtras.h"
31  #include <set>
32  using namespace clang;
33  
34  
35  
36  enum TryCastResult {
37    TC_NotApplicable, ///< The cast method is not applicable.
38    TC_Success,       ///< The cast method is appropriate and successful.
39    TC_Extension,     ///< The cast method is appropriate and accepted as a
40                      ///< language extension.
41    TC_Failed         ///< The cast method is appropriate, but failed. A
42                      ///< diagnostic has been emitted.
43  };
44  
45  static bool isValidCast(TryCastResult TCR) {
46    return TCR == TC_Success || TCR == TC_Extension;
47  }
48  
49  enum CastType {
50    CT_Const,       ///< const_cast
51    CT_Static,      ///< static_cast
52    CT_Reinterpret, ///< reinterpret_cast
53    CT_Dynamic,     ///< dynamic_cast
54    CT_CStyle,      ///< (Type)expr
55    CT_Functional,  ///< Type(expr)
56    CT_Addrspace    ///< addrspace_cast
57  };
58  
59  namespace {
60    struct CastOperation {
61      CastOperation(Sema &S, QualType destType, ExprResult src)
62        : Self(S), SrcExpr(src), DestType(destType),
63          ResultType(destType.getNonLValueExprType(S.Context)),
64          ValueKind(Expr::getValueKindForType(destType)),
65          Kind(CK_Dependent), IsARCUnbridgedCast(false) {
66  
67        // C++ [expr.type]/8.2.2:
68        //   If a pr-value initially has the type cv-T, where T is a
69        //   cv-unqualified non-class, non-array type, the type of the
70        //   expression is adjusted to T prior to any further analysis.
71        // C23 6.5.4p6:
72        //   Preceding an expression by a parenthesized type name converts the
73        //   value of the expression to the unqualified, non-atomic version of
74        //   the named type.
75        if (!S.Context.getLangOpts().ObjC && !DestType->isRecordType() &&
76            !DestType->isArrayType()) {
77          DestType = DestType.getAtomicUnqualifiedType();
78        }
79  
80        if (const BuiltinType *placeholder =
81              src.get()->getType()->getAsPlaceholderType()) {
82          PlaceholderKind = placeholder->getKind();
83        } else {
84          PlaceholderKind = (BuiltinType::Kind) 0;
85        }
86      }
87  
88      Sema &Self;
89      ExprResult SrcExpr;
90      QualType DestType;
91      QualType ResultType;
92      ExprValueKind ValueKind;
93      CastKind Kind;
94      BuiltinType::Kind PlaceholderKind;
95      CXXCastPath BasePath;
96      bool IsARCUnbridgedCast;
97  
98      SourceRange OpRange;
99      SourceRange DestRange;
100  
101      // Top-level semantics-checking routines.
102      void CheckConstCast();
103      void CheckReinterpretCast();
104      void CheckStaticCast();
105      void CheckDynamicCast();
106      void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
107      void CheckCStyleCast();
108      void CheckBuiltinBitCast();
109      void CheckAddrspaceCast();
110  
111      void updatePartOfExplicitCastFlags(CastExpr *CE) {
112        // Walk down from the CE to the OrigSrcExpr, and mark all immediate
113        // ImplicitCastExpr's as being part of ExplicitCastExpr. The original CE
114        // (which is a ExplicitCastExpr), and the OrigSrcExpr are not touched.
115        for (; auto *ICE = dyn_cast<ImplicitCastExpr>(CE->getSubExpr()); CE = ICE)
116          ICE->setIsPartOfExplicitCast(true);
117      }
118  
119      /// Complete an apparently-successful cast operation that yields
120      /// the given expression.
121      ExprResult complete(CastExpr *castExpr) {
122        // If this is an unbridged cast, wrap the result in an implicit
123        // cast that yields the unbridged-cast placeholder type.
124        if (IsARCUnbridgedCast) {
125          castExpr = ImplicitCastExpr::Create(
126              Self.Context, Self.Context.ARCUnbridgedCastTy, CK_Dependent,
127              castExpr, nullptr, castExpr->getValueKind(),
128              Self.CurFPFeatureOverrides());
129        }
130        updatePartOfExplicitCastFlags(castExpr);
131        return castExpr;
132      }
133  
134      // Internal convenience methods.
135  
136      /// Try to handle the given placeholder expression kind.  Return
137      /// true if the source expression has the appropriate placeholder
138      /// kind.  A placeholder can only be claimed once.
139      bool claimPlaceholder(BuiltinType::Kind K) {
140        if (PlaceholderKind != K) return false;
141  
142        PlaceholderKind = (BuiltinType::Kind) 0;
143        return true;
144      }
145  
146      bool isPlaceholder() const {
147        return PlaceholderKind != 0;
148      }
149      bool isPlaceholder(BuiltinType::Kind K) const {
150        return PlaceholderKind == K;
151      }
152  
153      // Language specific cast restrictions for address spaces.
154      void checkAddressSpaceCast(QualType SrcType, QualType DestType);
155  
156      void checkCastAlign() {
157        Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
158      }
159  
160      void checkObjCConversion(CheckedConversionKind CCK) {
161        assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers());
162  
163        Expr *src = SrcExpr.get();
164        if (Self.ObjC().CheckObjCConversion(OpRange, DestType, src, CCK) ==
165            SemaObjC::ACR_unbridged)
166          IsARCUnbridgedCast = true;
167        SrcExpr = src;
168      }
169  
170      /// Check for and handle non-overload placeholder expressions.
171      void checkNonOverloadPlaceholders() {
172        if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload))
173          return;
174  
175        SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
176        if (SrcExpr.isInvalid())
177          return;
178        PlaceholderKind = (BuiltinType::Kind) 0;
179      }
180    };
181  
182    void CheckNoDeref(Sema &S, const QualType FromType, const QualType ToType,
183                      SourceLocation OpLoc) {
184      if (const auto *PtrType = dyn_cast<PointerType>(FromType)) {
185        if (PtrType->getPointeeType()->hasAttr(attr::NoDeref)) {
186          if (const auto *DestType = dyn_cast<PointerType>(ToType)) {
187            if (!DestType->getPointeeType()->hasAttr(attr::NoDeref)) {
188              S.Diag(OpLoc, diag::warn_noderef_to_dereferenceable_pointer);
189            }
190          }
191        }
192      }
193    }
194  
195    struct CheckNoDerefRAII {
196      CheckNoDerefRAII(CastOperation &Op) : Op(Op) {}
197      ~CheckNoDerefRAII() {
198        if (!Op.SrcExpr.isInvalid())
199          CheckNoDeref(Op.Self, Op.SrcExpr.get()->getType(), Op.ResultType,
200                       Op.OpRange.getBegin());
201      }
202  
203      CastOperation &Op;
204    };
205  }
206  
207  static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
208                               QualType DestType);
209  
210  // The Try functions attempt a specific way of casting. If they succeed, they
211  // return TC_Success. If their way of casting is not appropriate for the given
212  // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
213  // to emit if no other way succeeds. If their way of casting is appropriate but
214  // fails, they return TC_Failed and *must* set diag; they can set it to 0 if
215  // they emit a specialized diagnostic.
216  // All diagnostics returned by these functions must expect the same three
217  // arguments:
218  // %0: Cast Type (a value from the CastType enumeration)
219  // %1: Source Type
220  // %2: Destination Type
221  static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
222                                             QualType DestType, bool CStyle,
223                                             CastKind &Kind,
224                                             CXXCastPath &BasePath,
225                                             unsigned &msg);
226  static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
227                                                 QualType DestType, bool CStyle,
228                                                 SourceRange OpRange,
229                                                 unsigned &msg,
230                                                 CastKind &Kind,
231                                                 CXXCastPath &BasePath);
232  static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
233                                                QualType DestType, bool CStyle,
234                                                SourceRange OpRange,
235                                                unsigned &msg,
236                                                CastKind &Kind,
237                                                CXXCastPath &BasePath);
238  static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
239                                         CanQualType DestType, bool CStyle,
240                                         SourceRange OpRange,
241                                         QualType OrigSrcType,
242                                         QualType OrigDestType, unsigned &msg,
243                                         CastKind &Kind,
244                                         CXXCastPath &BasePath);
245  static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
246                                                 QualType SrcType,
247                                                 QualType DestType,bool CStyle,
248                                                 SourceRange OpRange,
249                                                 unsigned &msg,
250                                                 CastKind &Kind,
251                                                 CXXCastPath &BasePath);
252  
253  static TryCastResult
254  TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
255                        CheckedConversionKind CCK, SourceRange OpRange,
256                        unsigned &msg, CastKind &Kind, bool ListInitialization);
257  static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
258                                     QualType DestType, CheckedConversionKind CCK,
259                                     SourceRange OpRange, unsigned &msg,
260                                     CastKind &Kind, CXXCastPath &BasePath,
261                                     bool ListInitialization);
262  static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
263                                    QualType DestType, bool CStyle,
264                                    unsigned &msg);
265  static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
266                                          QualType DestType, bool CStyle,
267                                          SourceRange OpRange, unsigned &msg,
268                                          CastKind &Kind);
269  static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr,
270                                           QualType DestType, bool CStyle,
271                                           unsigned &msg, CastKind &Kind);
272  
273  ExprResult
274  Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
275                          SourceLocation LAngleBracketLoc, Declarator &D,
276                          SourceLocation RAngleBracketLoc,
277                          SourceLocation LParenLoc, Expr *E,
278                          SourceLocation RParenLoc) {
279  
280    assert(!D.isInvalidType());
281  
282    TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
283    if (D.isInvalidType())
284      return ExprError();
285  
286    if (getLangOpts().CPlusPlus) {
287      // Check that there are no default arguments (C++ only).
288      CheckExtraCXXDefaultArguments(D);
289    }
290  
291    return BuildCXXNamedCast(OpLoc, Kind, TInfo, E,
292                             SourceRange(LAngleBracketLoc, RAngleBracketLoc),
293                             SourceRange(LParenLoc, RParenLoc));
294  }
295  
296  ExprResult
297  Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
298                          TypeSourceInfo *DestTInfo, Expr *E,
299                          SourceRange AngleBrackets, SourceRange Parens) {
300    ExprResult Ex = E;
301    QualType DestType = DestTInfo->getType();
302  
303    // If the type is dependent, we won't do the semantic analysis now.
304    bool TypeDependent =
305        DestType->isDependentType() || Ex.get()->isTypeDependent();
306  
307    CastOperation Op(*this, DestType, E);
308    Op.OpRange = SourceRange(OpLoc, Parens.getEnd());
309    Op.DestRange = AngleBrackets;
310  
311    switch (Kind) {
312    default: llvm_unreachable("Unknown C++ cast!");
313  
314    case tok::kw_addrspace_cast:
315      if (!TypeDependent) {
316        Op.CheckAddrspaceCast();
317        if (Op.SrcExpr.isInvalid())
318          return ExprError();
319      }
320      return Op.complete(CXXAddrspaceCastExpr::Create(
321          Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
322          DestTInfo, OpLoc, Parens.getEnd(), AngleBrackets));
323  
324    case tok::kw_const_cast:
325      if (!TypeDependent) {
326        Op.CheckConstCast();
327        if (Op.SrcExpr.isInvalid())
328          return ExprError();
329        DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
330      }
331      return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType,
332                                    Op.ValueKind, Op.SrcExpr.get(), DestTInfo,
333                                                  OpLoc, Parens.getEnd(),
334                                                  AngleBrackets));
335  
336    case tok::kw_dynamic_cast: {
337      // dynamic_cast is not supported in C++ for OpenCL.
338      if (getLangOpts().OpenCLCPlusPlus) {
339        return ExprError(Diag(OpLoc, diag::err_openclcxx_not_supported)
340                         << "dynamic_cast");
341      }
342  
343      if (!TypeDependent) {
344        Op.CheckDynamicCast();
345        if (Op.SrcExpr.isInvalid())
346          return ExprError();
347      }
348      return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType,
349                                      Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
350                                                    &Op.BasePath, DestTInfo,
351                                                    OpLoc, Parens.getEnd(),
352                                                    AngleBrackets));
353    }
354    case tok::kw_reinterpret_cast: {
355      if (!TypeDependent) {
356        Op.CheckReinterpretCast();
357        if (Op.SrcExpr.isInvalid())
358          return ExprError();
359        DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
360      }
361      return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType,
362                                      Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
363                                                        nullptr, DestTInfo, OpLoc,
364                                                        Parens.getEnd(),
365                                                        AngleBrackets));
366    }
367    case tok::kw_static_cast: {
368      if (!TypeDependent) {
369        Op.CheckStaticCast();
370        if (Op.SrcExpr.isInvalid())
371          return ExprError();
372        DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
373      }
374  
375      return Op.complete(CXXStaticCastExpr::Create(
376          Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
377          &Op.BasePath, DestTInfo, CurFPFeatureOverrides(), OpLoc,
378          Parens.getEnd(), AngleBrackets));
379    }
380    }
381  }
382  
383  ExprResult Sema::ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &D,
384                                           ExprResult Operand,
385                                           SourceLocation RParenLoc) {
386    assert(!D.isInvalidType());
387  
388    TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, Operand.get()->getType());
389    if (D.isInvalidType())
390      return ExprError();
391  
392    return BuildBuiltinBitCastExpr(KWLoc, TInfo, Operand.get(), RParenLoc);
393  }
394  
395  ExprResult Sema::BuildBuiltinBitCastExpr(SourceLocation KWLoc,
396                                           TypeSourceInfo *TSI, Expr *Operand,
397                                           SourceLocation RParenLoc) {
398    CastOperation Op(*this, TSI->getType(), Operand);
399    Op.OpRange = SourceRange(KWLoc, RParenLoc);
400    TypeLoc TL = TSI->getTypeLoc();
401    Op.DestRange = SourceRange(TL.getBeginLoc(), TL.getEndLoc());
402  
403    if (!Operand->isTypeDependent() && !TSI->getType()->isDependentType()) {
404      Op.CheckBuiltinBitCast();
405      if (Op.SrcExpr.isInvalid())
406        return ExprError();
407    }
408  
409    BuiltinBitCastExpr *BCE =
410        new (Context) BuiltinBitCastExpr(Op.ResultType, Op.ValueKind, Op.Kind,
411                                         Op.SrcExpr.get(), TSI, KWLoc, RParenLoc);
412    return Op.complete(BCE);
413  }
414  
415  /// Try to diagnose a failed overloaded cast.  Returns true if
416  /// diagnostics were emitted.
417  static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
418                                        SourceRange range, Expr *src,
419                                        QualType destType,
420                                        bool listInitialization) {
421    switch (CT) {
422    // These cast kinds don't consider user-defined conversions.
423    case CT_Const:
424    case CT_Reinterpret:
425    case CT_Dynamic:
426    case CT_Addrspace:
427      return false;
428  
429    // These do.
430    case CT_Static:
431    case CT_CStyle:
432    case CT_Functional:
433      break;
434    }
435  
436    QualType srcType = src->getType();
437    if (!destType->isRecordType() && !srcType->isRecordType())
438      return false;
439  
440    InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
441    InitializationKind initKind
442      = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
443                                                        range, listInitialization)
444      : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
445                                                               listInitialization)
446      : InitializationKind::CreateCast(/*type range?*/ range);
447    InitializationSequence sequence(S, entity, initKind, src);
448  
449    assert(sequence.Failed() && "initialization succeeded on second try?");
450    switch (sequence.getFailureKind()) {
451    default: return false;
452  
453    case InitializationSequence::FK_ParenthesizedListInitFailed:
454      // In C++20, if the underlying destination type is a RecordType, Clang
455      // attempts to perform parentesized aggregate initialization if constructor
456      // overload fails:
457      //
458      // C++20 [expr.static.cast]p4:
459      //   An expression E can be explicitly converted to a type T...if overload
460      //   resolution for a direct-initialization...would find at least one viable
461      //   function ([over.match.viable]), or if T is an aggregate type having a
462      //   first element X and there is an implicit conversion sequence from E to
463      //   the type of X.
464      //
465      // If that fails, then we'll generate the diagnostics from the failed
466      // previous constructor overload attempt. Array initialization, however, is
467      // not done after attempting constructor overloading, so we exit as there
468      // won't be a failed overload result.
469      if (destType->isArrayType())
470        return false;
471      break;
472    case InitializationSequence::FK_ConstructorOverloadFailed:
473    case InitializationSequence::FK_UserConversionOverloadFailed:
474      break;
475    }
476  
477    OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
478  
479    unsigned msg = 0;
480    OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
481  
482    switch (sequence.getFailedOverloadResult()) {
483    case OR_Success: llvm_unreachable("successful failed overload");
484    case OR_No_Viable_Function:
485      if (candidates.empty())
486        msg = diag::err_ovl_no_conversion_in_cast;
487      else
488        msg = diag::err_ovl_no_viable_conversion_in_cast;
489      howManyCandidates = OCD_AllCandidates;
490      break;
491  
492    case OR_Ambiguous:
493      msg = diag::err_ovl_ambiguous_conversion_in_cast;
494      howManyCandidates = OCD_AmbiguousCandidates;
495      break;
496  
497    case OR_Deleted: {
498      OverloadCandidateSet::iterator Best;
499      [[maybe_unused]] OverloadingResult Res =
500          candidates.BestViableFunction(S, range.getBegin(), Best);
501      assert(Res == OR_Deleted && "Inconsistent overload resolution");
502  
503      StringLiteral *Msg = Best->Function->getDeletedMessage();
504      candidates.NoteCandidates(
505          PartialDiagnosticAt(range.getBegin(),
506                              S.PDiag(diag::err_ovl_deleted_conversion_in_cast)
507                                  << CT << srcType << destType << (Msg != nullptr)
508                                  << (Msg ? Msg->getString() : StringRef())
509                                  << range << src->getSourceRange()),
510          S, OCD_ViableCandidates, src);
511      return true;
512    }
513    }
514  
515    candidates.NoteCandidates(
516        PartialDiagnosticAt(range.getBegin(),
517                            S.PDiag(msg) << CT << srcType << destType << range
518                                         << src->getSourceRange()),
519        S, howManyCandidates, src);
520  
521    return true;
522  }
523  
524  /// Diagnose a failed cast.
525  static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
526                              SourceRange opRange, Expr *src, QualType destType,
527                              bool listInitialization) {
528    if (msg == diag::err_bad_cxx_cast_generic &&
529        tryDiagnoseOverloadedCast(S, castType, opRange, src, destType,
530                                  listInitialization))
531      return;
532  
533    S.Diag(opRange.getBegin(), msg) << castType
534      << src->getType() << destType << opRange << src->getSourceRange();
535  
536    // Detect if both types are (ptr to) class, and note any incompleteness.
537    int DifferentPtrness = 0;
538    QualType From = destType;
539    if (auto Ptr = From->getAs<PointerType>()) {
540      From = Ptr->getPointeeType();
541      DifferentPtrness++;
542    }
543    QualType To = src->getType();
544    if (auto Ptr = To->getAs<PointerType>()) {
545      To = Ptr->getPointeeType();
546      DifferentPtrness--;
547    }
548    if (!DifferentPtrness) {
549      auto RecFrom = From->getAs<RecordType>();
550      auto RecTo = To->getAs<RecordType>();
551      if (RecFrom && RecTo) {
552        auto DeclFrom = RecFrom->getAsCXXRecordDecl();
553        if (!DeclFrom->isCompleteDefinition())
554          S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete) << DeclFrom;
555        auto DeclTo = RecTo->getAsCXXRecordDecl();
556        if (!DeclTo->isCompleteDefinition())
557          S.Diag(DeclTo->getLocation(), diag::note_type_incomplete) << DeclTo;
558      }
559    }
560  }
561  
562  namespace {
563  /// The kind of unwrapping we did when determining whether a conversion casts
564  /// away constness.
565  enum CastAwayConstnessKind {
566    /// The conversion does not cast away constness.
567    CACK_None = 0,
568    /// We unwrapped similar types.
569    CACK_Similar = 1,
570    /// We unwrapped dissimilar types with similar representations (eg, a pointer
571    /// versus an Objective-C object pointer).
572    CACK_SimilarKind = 2,
573    /// We unwrapped representationally-unrelated types, such as a pointer versus
574    /// a pointer-to-member.
575    CACK_Incoherent = 3,
576  };
577  }
578  
579  /// Unwrap one level of types for CastsAwayConstness.
580  ///
581  /// Like Sema::UnwrapSimilarTypes, this removes one level of indirection from
582  /// both types, provided that they're both pointer-like or array-like. Unlike
583  /// the Sema function, doesn't care if the unwrapped pieces are related.
584  ///
585  /// This function may remove additional levels as necessary for correctness:
586  /// the resulting T1 is unwrapped sufficiently that it is never an array type,
587  /// so that its qualifiers can be directly compared to those of T2 (which will
588  /// have the combined set of qualifiers from all indermediate levels of T2),
589  /// as (effectively) required by [expr.const.cast]p7 replacing T1's qualifiers
590  /// with those from T2.
591  static CastAwayConstnessKind
592  unwrapCastAwayConstnessLevel(ASTContext &Context, QualType &T1, QualType &T2) {
593    enum { None, Ptr, MemPtr, BlockPtr, Array };
594    auto Classify = [](QualType T) {
595      if (T->isAnyPointerType()) return Ptr;
596      if (T->isMemberPointerType()) return MemPtr;
597      if (T->isBlockPointerType()) return BlockPtr;
598      // We somewhat-arbitrarily don't look through VLA types here. This is at
599      // least consistent with the behavior of UnwrapSimilarTypes.
600      if (T->isConstantArrayType() || T->isIncompleteArrayType()) return Array;
601      return None;
602    };
603  
604    auto Unwrap = [&](QualType T) {
605      if (auto *AT = Context.getAsArrayType(T))
606        return AT->getElementType();
607      return T->getPointeeType();
608    };
609  
610    CastAwayConstnessKind Kind;
611  
612    if (T2->isReferenceType()) {
613      // Special case: if the destination type is a reference type, unwrap it as
614      // the first level. (The source will have been an lvalue expression in this
615      // case, so there is no corresponding "reference to" in T1 to remove.) This
616      // simulates removing a "pointer to" from both sides.
617      T2 = T2->getPointeeType();
618      Kind = CastAwayConstnessKind::CACK_Similar;
619    } else if (Context.UnwrapSimilarTypes(T1, T2)) {
620      Kind = CastAwayConstnessKind::CACK_Similar;
621    } else {
622      // Try unwrapping mismatching levels.
623      int T1Class = Classify(T1);
624      if (T1Class == None)
625        return CastAwayConstnessKind::CACK_None;
626  
627      int T2Class = Classify(T2);
628      if (T2Class == None)
629        return CastAwayConstnessKind::CACK_None;
630  
631      T1 = Unwrap(T1);
632      T2 = Unwrap(T2);
633      Kind = T1Class == T2Class ? CastAwayConstnessKind::CACK_SimilarKind
634                                : CastAwayConstnessKind::CACK_Incoherent;
635    }
636  
637    // We've unwrapped at least one level. If the resulting T1 is a (possibly
638    // multidimensional) array type, any qualifier on any matching layer of
639    // T2 is considered to correspond to T1. Decompose down to the element
640    // type of T1 so that we can compare properly.
641    while (true) {
642      Context.UnwrapSimilarArrayTypes(T1, T2);
643  
644      if (Classify(T1) != Array)
645        break;
646  
647      auto T2Class = Classify(T2);
648      if (T2Class == None)
649        break;
650  
651      if (T2Class != Array)
652        Kind = CastAwayConstnessKind::CACK_Incoherent;
653      else if (Kind != CastAwayConstnessKind::CACK_Incoherent)
654        Kind = CastAwayConstnessKind::CACK_SimilarKind;
655  
656      T1 = Unwrap(T1);
657      T2 = Unwrap(T2).withCVRQualifiers(T2.getCVRQualifiers());
658    }
659  
660    return Kind;
661  }
662  
663  /// Check if the pointer conversion from SrcType to DestType casts away
664  /// constness as defined in C++ [expr.const.cast]. This is used by the cast
665  /// checkers. Both arguments must denote pointer (possibly to member) types.
666  ///
667  /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
668  /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
669  static CastAwayConstnessKind
670  CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
671                     bool CheckCVR, bool CheckObjCLifetime,
672                     QualType *TheOffendingSrcType = nullptr,
673                     QualType *TheOffendingDestType = nullptr,
674                     Qualifiers *CastAwayQualifiers = nullptr) {
675    // If the only checking we care about is for Objective-C lifetime qualifiers,
676    // and we're not in ObjC mode, there's nothing to check.
677    if (!CheckCVR && CheckObjCLifetime && !Self.Context.getLangOpts().ObjC)
678      return CastAwayConstnessKind::CACK_None;
679  
680    if (!DestType->isReferenceType()) {
681      assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
682              SrcType->isBlockPointerType()) &&
683             "Source type is not pointer or pointer to member.");
684      assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
685              DestType->isBlockPointerType()) &&
686             "Destination type is not pointer or pointer to member.");
687    }
688  
689    QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
690             UnwrappedDestType = Self.Context.getCanonicalType(DestType);
691  
692    // Find the qualifiers. We only care about cvr-qualifiers for the
693    // purpose of this check, because other qualifiers (address spaces,
694    // Objective-C GC, etc.) are part of the type's identity.
695    QualType PrevUnwrappedSrcType = UnwrappedSrcType;
696    QualType PrevUnwrappedDestType = UnwrappedDestType;
697    auto WorstKind = CastAwayConstnessKind::CACK_Similar;
698    bool AllConstSoFar = true;
699    while (auto Kind = unwrapCastAwayConstnessLevel(
700               Self.Context, UnwrappedSrcType, UnwrappedDestType)) {
701      // Track the worst kind of unwrap we needed to do before we found a
702      // problem.
703      if (Kind > WorstKind)
704        WorstKind = Kind;
705  
706      // Determine the relevant qualifiers at this level.
707      Qualifiers SrcQuals, DestQuals;
708      Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
709      Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
710  
711      // We do not meaningfully track object const-ness of Objective-C object
712      // types. Remove const from the source type if either the source or
713      // the destination is an Objective-C object type.
714      if (UnwrappedSrcType->isObjCObjectType() ||
715          UnwrappedDestType->isObjCObjectType())
716        SrcQuals.removeConst();
717  
718      if (CheckCVR) {
719        Qualifiers SrcCvrQuals =
720            Qualifiers::fromCVRMask(SrcQuals.getCVRQualifiers());
721        Qualifiers DestCvrQuals =
722            Qualifiers::fromCVRMask(DestQuals.getCVRQualifiers());
723  
724        if (SrcCvrQuals != DestCvrQuals) {
725          if (CastAwayQualifiers)
726            *CastAwayQualifiers = SrcCvrQuals - DestCvrQuals;
727  
728          // If we removed a cvr-qualifier, this is casting away 'constness'.
729          if (!DestCvrQuals.compatiblyIncludes(SrcCvrQuals)) {
730            if (TheOffendingSrcType)
731              *TheOffendingSrcType = PrevUnwrappedSrcType;
732            if (TheOffendingDestType)
733              *TheOffendingDestType = PrevUnwrappedDestType;
734            return WorstKind;
735          }
736  
737          // If any prior level was not 'const', this is also casting away
738          // 'constness'. We noted the outermost type missing a 'const' already.
739          if (!AllConstSoFar)
740            return WorstKind;
741        }
742      }
743  
744      if (CheckObjCLifetime &&
745          !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
746        return WorstKind;
747  
748      // If we found our first non-const-qualified type, this may be the place
749      // where things start to go wrong.
750      if (AllConstSoFar && !DestQuals.hasConst()) {
751        AllConstSoFar = false;
752        if (TheOffendingSrcType)
753          *TheOffendingSrcType = PrevUnwrappedSrcType;
754        if (TheOffendingDestType)
755          *TheOffendingDestType = PrevUnwrappedDestType;
756      }
757  
758      PrevUnwrappedSrcType = UnwrappedSrcType;
759      PrevUnwrappedDestType = UnwrappedDestType;
760    }
761  
762    return CastAwayConstnessKind::CACK_None;
763  }
764  
765  static TryCastResult getCastAwayConstnessCastKind(CastAwayConstnessKind CACK,
766                                                    unsigned &DiagID) {
767    switch (CACK) {
768    case CastAwayConstnessKind::CACK_None:
769      llvm_unreachable("did not cast away constness");
770  
771    case CastAwayConstnessKind::CACK_Similar:
772      // FIXME: Accept these as an extension too?
773    case CastAwayConstnessKind::CACK_SimilarKind:
774      DiagID = diag::err_bad_cxx_cast_qualifiers_away;
775      return TC_Failed;
776  
777    case CastAwayConstnessKind::CACK_Incoherent:
778      DiagID = diag::ext_bad_cxx_cast_qualifiers_away_incoherent;
779      return TC_Extension;
780    }
781  
782    llvm_unreachable("unexpected cast away constness kind");
783  }
784  
785  /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
786  /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
787  /// checked downcasts in class hierarchies.
788  void CastOperation::CheckDynamicCast() {
789    CheckNoDerefRAII NoderefCheck(*this);
790  
791    if (ValueKind == VK_PRValue)
792      SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
793    else if (isPlaceholder())
794      SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
795    if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
796      return;
797  
798    QualType OrigSrcType = SrcExpr.get()->getType();
799    QualType DestType = Self.Context.getCanonicalType(this->DestType);
800  
801    // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
802    //   or "pointer to cv void".
803  
804    QualType DestPointee;
805    const PointerType *DestPointer = DestType->getAs<PointerType>();
806    const ReferenceType *DestReference = nullptr;
807    if (DestPointer) {
808      DestPointee = DestPointer->getPointeeType();
809    } else if ((DestReference = DestType->getAs<ReferenceType>())) {
810      DestPointee = DestReference->getPointeeType();
811    } else {
812      Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
813        << this->DestType << DestRange;
814      SrcExpr = ExprError();
815      return;
816    }
817  
818    const RecordType *DestRecord = DestPointee->getAs<RecordType>();
819    if (DestPointee->isVoidType()) {
820      assert(DestPointer && "Reference to void is not possible");
821    } else if (DestRecord) {
822      if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
823                                   diag::err_bad_cast_incomplete,
824                                   DestRange)) {
825        SrcExpr = ExprError();
826        return;
827      }
828    } else {
829      Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
830        << DestPointee.getUnqualifiedType() << DestRange;
831      SrcExpr = ExprError();
832      return;
833    }
834  
835    // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
836    //   complete class type, [...]. If T is an lvalue reference type, v shall be
837    //   an lvalue of a complete class type, [...]. If T is an rvalue reference
838    //   type, v shall be an expression having a complete class type, [...]
839    QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
840    QualType SrcPointee;
841    if (DestPointer) {
842      if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
843        SrcPointee = SrcPointer->getPointeeType();
844      } else {
845        Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
846            << OrigSrcType << this->DestType << SrcExpr.get()->getSourceRange();
847        SrcExpr = ExprError();
848        return;
849      }
850    } else if (DestReference->isLValueReferenceType()) {
851      if (!SrcExpr.get()->isLValue()) {
852        Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
853          << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
854      }
855      SrcPointee = SrcType;
856    } else {
857      // If we're dynamic_casting from a prvalue to an rvalue reference, we need
858      // to materialize the prvalue before we bind the reference to it.
859      if (SrcExpr.get()->isPRValue())
860        SrcExpr = Self.CreateMaterializeTemporaryExpr(
861            SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
862      SrcPointee = SrcType;
863    }
864  
865    const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
866    if (SrcRecord) {
867      if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
868                                   diag::err_bad_cast_incomplete,
869                                   SrcExpr.get())) {
870        SrcExpr = ExprError();
871        return;
872      }
873    } else {
874      Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
875        << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
876      SrcExpr = ExprError();
877      return;
878    }
879  
880    assert((DestPointer || DestReference) &&
881      "Bad destination non-ptr/ref slipped through.");
882    assert((DestRecord || DestPointee->isVoidType()) &&
883      "Bad destination pointee slipped through.");
884    assert(SrcRecord && "Bad source pointee slipped through.");
885  
886    // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
887    if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
888      Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
889        << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
890      SrcExpr = ExprError();
891      return;
892    }
893  
894    // C++ 5.2.7p3: If the type of v is the same as the required result type,
895    //   [except for cv].
896    if (DestRecord == SrcRecord) {
897      Kind = CK_NoOp;
898      return;
899    }
900  
901    // C++ 5.2.7p5
902    // Upcasts are resolved statically.
903    if (DestRecord &&
904        Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) {
905      if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
906                                             OpRange.getBegin(), OpRange,
907                                             &BasePath)) {
908        SrcExpr = ExprError();
909        return;
910      }
911  
912      Kind = CK_DerivedToBase;
913      return;
914    }
915  
916    // C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
917    const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
918    assert(SrcDecl && "Definition missing");
919    if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
920      Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
921        << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
922      SrcExpr = ExprError();
923    }
924  
925    // dynamic_cast is not available with -fno-rtti.
926    // As an exception, dynamic_cast to void* is available because it doesn't
927    // use RTTI.
928    if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) {
929      Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti);
930      SrcExpr = ExprError();
931      return;
932    }
933  
934    // Warns when dynamic_cast is used with RTTI data disabled.
935    if (!Self.getLangOpts().RTTIData) {
936      bool MicrosoftABI =
937          Self.getASTContext().getTargetInfo().getCXXABI().isMicrosoft();
938      bool isClangCL = Self.getDiagnostics().getDiagnosticOptions().getFormat() ==
939                       DiagnosticOptions::MSVC;
940      if (MicrosoftABI || !DestPointee->isVoidType())
941        Self.Diag(OpRange.getBegin(),
942                  diag::warn_no_dynamic_cast_with_rtti_disabled)
943            << isClangCL;
944    }
945  
946    // For a dynamic_cast to a final type, IR generation might emit a reference
947    // to the vtable.
948    if (DestRecord) {
949      auto *DestDecl = DestRecord->getAsCXXRecordDecl();
950      if (DestDecl->isEffectivelyFinal())
951        Self.MarkVTableUsed(OpRange.getBegin(), DestDecl);
952    }
953  
954    // Done. Everything else is run-time checks.
955    Kind = CK_Dynamic;
956  }
957  
958  /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
959  /// Refer to C++ 5.2.11 for details. const_cast is typically used in code
960  /// like this:
961  /// const char *str = "literal";
962  /// legacy_function(const_cast\<char*\>(str));
963  void CastOperation::CheckConstCast() {
964    CheckNoDerefRAII NoderefCheck(*this);
965  
966    if (ValueKind == VK_PRValue)
967      SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
968    else if (isPlaceholder())
969      SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
970    if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
971      return;
972  
973    unsigned msg = diag::err_bad_cxx_cast_generic;
974    auto TCR = TryConstCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg);
975    if (TCR != TC_Success && msg != 0) {
976      Self.Diag(OpRange.getBegin(), msg) << CT_Const
977        << SrcExpr.get()->getType() << DestType << OpRange;
978    }
979    if (!isValidCast(TCR))
980      SrcExpr = ExprError();
981  }
982  
983  void CastOperation::CheckAddrspaceCast() {
984    unsigned msg = diag::err_bad_cxx_cast_generic;
985    auto TCR =
986        TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg, Kind);
987    if (TCR != TC_Success && msg != 0) {
988      Self.Diag(OpRange.getBegin(), msg)
989          << CT_Addrspace << SrcExpr.get()->getType() << DestType << OpRange;
990    }
991    if (!isValidCast(TCR))
992      SrcExpr = ExprError();
993  }
994  
995  /// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
996  /// or downcast between respective pointers or references.
997  static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
998                                            QualType DestType,
999                                            SourceRange OpRange) {
1000    QualType SrcType = SrcExpr->getType();
1001    // When casting from pointer or reference, get pointee type; use original
1002    // type otherwise.
1003    const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
1004    const CXXRecordDecl *SrcRD =
1005      SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
1006  
1007    // Examining subobjects for records is only possible if the complete and
1008    // valid definition is available.  Also, template instantiation is not
1009    // allowed here.
1010    if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
1011      return;
1012  
1013    const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
1014  
1015    if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
1016      return;
1017  
1018    enum {
1019      ReinterpretUpcast,
1020      ReinterpretDowncast
1021    } ReinterpretKind;
1022  
1023    CXXBasePaths BasePaths;
1024  
1025    if (SrcRD->isDerivedFrom(DestRD, BasePaths))
1026      ReinterpretKind = ReinterpretUpcast;
1027    else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
1028      ReinterpretKind = ReinterpretDowncast;
1029    else
1030      return;
1031  
1032    bool VirtualBase = true;
1033    bool NonZeroOffset = false;
1034    for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
1035                                            E = BasePaths.end();
1036         I != E; ++I) {
1037      const CXXBasePath &Path = *I;
1038      CharUnits Offset = CharUnits::Zero();
1039      bool IsVirtual = false;
1040      for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
1041           IElem != EElem; ++IElem) {
1042        IsVirtual = IElem->Base->isVirtual();
1043        if (IsVirtual)
1044          break;
1045        const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
1046        assert(BaseRD && "Base type should be a valid unqualified class type");
1047        // Don't check if any base has invalid declaration or has no definition
1048        // since it has no layout info.
1049        const CXXRecordDecl *Class = IElem->Class,
1050                            *ClassDefinition = Class->getDefinition();
1051        if (Class->isInvalidDecl() || !ClassDefinition ||
1052            !ClassDefinition->isCompleteDefinition())
1053          return;
1054  
1055        const ASTRecordLayout &DerivedLayout =
1056            Self.Context.getASTRecordLayout(Class);
1057        Offset += DerivedLayout.getBaseClassOffset(BaseRD);
1058      }
1059      if (!IsVirtual) {
1060        // Don't warn if any path is a non-virtually derived base at offset zero.
1061        if (Offset.isZero())
1062          return;
1063        // Offset makes sense only for non-virtual bases.
1064        else
1065          NonZeroOffset = true;
1066      }
1067      VirtualBase = VirtualBase && IsVirtual;
1068    }
1069  
1070    (void) NonZeroOffset; // Silence set but not used warning.
1071    assert((VirtualBase || NonZeroOffset) &&
1072           "Should have returned if has non-virtual base with zero offset");
1073  
1074    QualType BaseType =
1075        ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
1076    QualType DerivedType =
1077        ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
1078  
1079    SourceLocation BeginLoc = OpRange.getBegin();
1080    Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
1081      << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind)
1082      << OpRange;
1083    Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
1084      << int(ReinterpretKind)
1085      << FixItHint::CreateReplacement(BeginLoc, "static_cast");
1086  }
1087  
1088  static bool argTypeIsABIEquivalent(QualType SrcType, QualType DestType,
1089                                     ASTContext &Context) {
1090    if (SrcType->isPointerType() && DestType->isPointerType())
1091      return true;
1092  
1093    // Allow integral type mismatch if their size are equal.
1094    if ((SrcType->isIntegralType(Context) || SrcType->isEnumeralType()) &&
1095        (DestType->isIntegralType(Context) || DestType->isEnumeralType()))
1096      if (Context.getTypeSizeInChars(SrcType) ==
1097          Context.getTypeSizeInChars(DestType))
1098        return true;
1099  
1100    return Context.hasSameUnqualifiedType(SrcType, DestType);
1101  }
1102  
1103  static unsigned int checkCastFunctionType(Sema &Self, const ExprResult &SrcExpr,
1104                                            QualType DestType) {
1105    unsigned int DiagID = 0;
1106    const unsigned int DiagList[] = {diag::warn_cast_function_type_strict,
1107                                     diag::warn_cast_function_type};
1108    for (auto ID : DiagList) {
1109      if (!Self.Diags.isIgnored(ID, SrcExpr.get()->getExprLoc())) {
1110        DiagID = ID;
1111        break;
1112      }
1113    }
1114    if (!DiagID)
1115      return 0;
1116  
1117    QualType SrcType = SrcExpr.get()->getType();
1118    const FunctionType *SrcFTy = nullptr;
1119    const FunctionType *DstFTy = nullptr;
1120    if (((SrcType->isBlockPointerType() || SrcType->isFunctionPointerType()) &&
1121         DestType->isFunctionPointerType()) ||
1122        (SrcType->isMemberFunctionPointerType() &&
1123         DestType->isMemberFunctionPointerType())) {
1124      SrcFTy = SrcType->getPointeeType()->castAs<FunctionType>();
1125      DstFTy = DestType->getPointeeType()->castAs<FunctionType>();
1126    } else if (SrcType->isFunctionType() && DestType->isFunctionReferenceType()) {
1127      SrcFTy = SrcType->castAs<FunctionType>();
1128      DstFTy = DestType.getNonReferenceType()->castAs<FunctionType>();
1129    } else {
1130      return 0;
1131    }
1132    assert(SrcFTy && DstFTy);
1133  
1134    if (Self.Context.hasSameType(SrcFTy, DstFTy))
1135      return 0;
1136  
1137    // For strict checks, ensure we have an exact match.
1138    if (DiagID == diag::warn_cast_function_type_strict)
1139      return DiagID;
1140  
1141    auto IsVoidVoid = [](const FunctionType *T) {
1142      if (!T->getReturnType()->isVoidType())
1143        return false;
1144      if (const auto *PT = T->getAs<FunctionProtoType>())
1145        return !PT->isVariadic() && PT->getNumParams() == 0;
1146      return false;
1147    };
1148  
1149    // Skip if either function type is void(*)(void)
1150    if (IsVoidVoid(SrcFTy) || IsVoidVoid(DstFTy))
1151      return 0;
1152  
1153    // Check return type.
1154    if (!argTypeIsABIEquivalent(SrcFTy->getReturnType(), DstFTy->getReturnType(),
1155                                Self.Context))
1156      return DiagID;
1157  
1158    // Check if either has unspecified number of parameters
1159    if (SrcFTy->isFunctionNoProtoType() || DstFTy->isFunctionNoProtoType())
1160      return 0;
1161  
1162    // Check parameter types.
1163  
1164    const auto *SrcFPTy = cast<FunctionProtoType>(SrcFTy);
1165    const auto *DstFPTy = cast<FunctionProtoType>(DstFTy);
1166  
1167    // In a cast involving function types with a variable argument list only the
1168    // types of initial arguments that are provided are considered.
1169    unsigned NumParams = SrcFPTy->getNumParams();
1170    unsigned DstNumParams = DstFPTy->getNumParams();
1171    if (NumParams > DstNumParams) {
1172      if (!DstFPTy->isVariadic())
1173        return DiagID;
1174      NumParams = DstNumParams;
1175    } else if (NumParams < DstNumParams) {
1176      if (!SrcFPTy->isVariadic())
1177        return DiagID;
1178    }
1179  
1180    for (unsigned i = 0; i < NumParams; ++i)
1181      if (!argTypeIsABIEquivalent(SrcFPTy->getParamType(i),
1182                                  DstFPTy->getParamType(i), Self.Context))
1183        return DiagID;
1184  
1185    return 0;
1186  }
1187  
1188  /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
1189  /// valid.
1190  /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
1191  /// like this:
1192  /// char *bytes = reinterpret_cast\<char*\>(int_ptr);
1193  void CastOperation::CheckReinterpretCast() {
1194    if (ValueKind == VK_PRValue && !isPlaceholder(BuiltinType::Overload))
1195      SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
1196    else
1197      checkNonOverloadPlaceholders();
1198    if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
1199      return;
1200  
1201    unsigned msg = diag::err_bad_cxx_cast_generic;
1202    TryCastResult tcr =
1203      TryReinterpretCast(Self, SrcExpr, DestType,
1204                         /*CStyle*/false, OpRange, msg, Kind);
1205    if (tcr != TC_Success && msg != 0) {
1206      if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
1207        return;
1208      if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1209        //FIXME: &f<int>; is overloaded and resolvable
1210        Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
1211          << OverloadExpr::find(SrcExpr.get()).Expression->getName()
1212          << DestType << OpRange;
1213        Self.NoteAllOverloadCandidates(SrcExpr.get());
1214  
1215      } else {
1216        diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
1217                        DestType, /*listInitialization=*/false);
1218      }
1219    }
1220  
1221    if (isValidCast(tcr)) {
1222      if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
1223        checkObjCConversion(CheckedConversionKind::OtherCast);
1224      DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
1225  
1226      if (unsigned DiagID = checkCastFunctionType(Self, SrcExpr, DestType))
1227        Self.Diag(OpRange.getBegin(), DiagID)
1228            << SrcExpr.get()->getType() << DestType << OpRange;
1229    } else {
1230      SrcExpr = ExprError();
1231    }
1232  }
1233  
1234  
1235  /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
1236  /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
1237  /// implicit conversions explicit and getting rid of data loss warnings.
1238  void CastOperation::CheckStaticCast() {
1239    CheckNoDerefRAII NoderefCheck(*this);
1240  
1241    if (isPlaceholder()) {
1242      checkNonOverloadPlaceholders();
1243      if (SrcExpr.isInvalid())
1244        return;
1245    }
1246  
1247    // This test is outside everything else because it's the only case where
1248    // a non-lvalue-reference target type does not lead to decay.
1249    // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
1250    if (DestType->isVoidType()) {
1251      Kind = CK_ToVoid;
1252  
1253      if (claimPlaceholder(BuiltinType::Overload)) {
1254        Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr,
1255                  false, // Decay Function to ptr
1256                  true, // Complain
1257                  OpRange, DestType, diag::err_bad_static_cast_overload);
1258        if (SrcExpr.isInvalid())
1259          return;
1260      }
1261  
1262      SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
1263      return;
1264    }
1265  
1266    if (ValueKind == VK_PRValue && !DestType->isRecordType() &&
1267        !isPlaceholder(BuiltinType::Overload)) {
1268      SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
1269      if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
1270        return;
1271    }
1272  
1273    unsigned msg = diag::err_bad_cxx_cast_generic;
1274    TryCastResult tcr =
1275        TryStaticCast(Self, SrcExpr, DestType, CheckedConversionKind::OtherCast,
1276                      OpRange, msg, Kind, BasePath, /*ListInitialization=*/false);
1277    if (tcr != TC_Success && msg != 0) {
1278      if (SrcExpr.isInvalid())
1279        return;
1280      if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1281        OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
1282        Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
1283          << oe->getName() << DestType << OpRange
1284          << oe->getQualifierLoc().getSourceRange();
1285        Self.NoteAllOverloadCandidates(SrcExpr.get());
1286      } else {
1287        diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType,
1288                        /*listInitialization=*/false);
1289      }
1290    }
1291  
1292    if (isValidCast(tcr)) {
1293      if (Kind == CK_BitCast)
1294        checkCastAlign();
1295      if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
1296        checkObjCConversion(CheckedConversionKind::OtherCast);
1297    } else {
1298      SrcExpr = ExprError();
1299    }
1300  }
1301  
1302  static bool IsAddressSpaceConversion(QualType SrcType, QualType DestType) {
1303    auto *SrcPtrType = SrcType->getAs<PointerType>();
1304    if (!SrcPtrType)
1305      return false;
1306    auto *DestPtrType = DestType->getAs<PointerType>();
1307    if (!DestPtrType)
1308      return false;
1309    return SrcPtrType->getPointeeType().getAddressSpace() !=
1310           DestPtrType->getPointeeType().getAddressSpace();
1311  }
1312  
1313  /// TryStaticCast - Check if a static cast can be performed, and do so if
1314  /// possible. If @p CStyle, ignore access restrictions on hierarchy casting
1315  /// and casting away constness.
1316  static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
1317                                     QualType DestType, CheckedConversionKind CCK,
1318                                     SourceRange OpRange, unsigned &msg,
1319                                     CastKind &Kind, CXXCastPath &BasePath,
1320                                     bool ListInitialization) {
1321    // Determine whether we have the semantics of a C-style cast.
1322    bool CStyle = (CCK == CheckedConversionKind::CStyleCast ||
1323                   CCK == CheckedConversionKind::FunctionalCast);
1324  
1325    // The order the tests is not entirely arbitrary. There is one conversion
1326    // that can be handled in two different ways. Given:
1327    // struct A {};
1328    // struct B : public A {
1329    //   B(); B(const A&);
1330    // };
1331    // const A &a = B();
1332    // the cast static_cast<const B&>(a) could be seen as either a static
1333    // reference downcast, or an explicit invocation of the user-defined
1334    // conversion using B's conversion constructor.
1335    // DR 427 specifies that the downcast is to be applied here.
1336  
1337    // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
1338    // Done outside this function.
1339  
1340    TryCastResult tcr;
1341  
1342    // C++ 5.2.9p5, reference downcast.
1343    // See the function for details.
1344    // DR 427 specifies that this is to be applied before paragraph 2.
1345    tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle,
1346                                     OpRange, msg, Kind, BasePath);
1347    if (tcr != TC_NotApplicable)
1348      return tcr;
1349  
1350    // C++11 [expr.static.cast]p3:
1351    //   A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2
1352    //   T2" if "cv2 T2" is reference-compatible with "cv1 T1".
1353    tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind,
1354                                BasePath, msg);
1355    if (tcr != TC_NotApplicable)
1356      return tcr;
1357  
1358    // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
1359    //   [...] if the declaration "T t(e);" is well-formed, [...].
1360    tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg,
1361                                Kind, ListInitialization);
1362    if (SrcExpr.isInvalid())
1363      return TC_Failed;
1364    if (tcr != TC_NotApplicable)
1365      return tcr;
1366  
1367    // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
1368    // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
1369    // conversions, subject to further restrictions.
1370    // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
1371    // of qualification conversions impossible. (In C++20, adding an array bound
1372    // would be the reverse of a qualification conversion, but adding permission
1373    // to add an array bound in a static_cast is a wording oversight.)
1374    // In the CStyle case, the earlier attempt to const_cast should have taken
1375    // care of reverse qualification conversions.
1376  
1377    QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType());
1378  
1379    // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
1380    // converted to an integral type. [...] A value of a scoped enumeration type
1381    // can also be explicitly converted to a floating-point type [...].
1382    if (const EnumType *Enum = SrcType->getAs<EnumType>()) {
1383      if (Enum->getDecl()->isScoped()) {
1384        if (DestType->isBooleanType()) {
1385          Kind = CK_IntegralToBoolean;
1386          return TC_Success;
1387        } else if (DestType->isIntegralType(Self.Context)) {
1388          Kind = CK_IntegralCast;
1389          return TC_Success;
1390        } else if (DestType->isRealFloatingType()) {
1391          Kind = CK_IntegralToFloating;
1392          return TC_Success;
1393        }
1394      }
1395    }
1396  
1397    // Reverse integral promotion/conversion. All such conversions are themselves
1398    // again integral promotions or conversions and are thus already handled by
1399    // p2 (TryDirectInitialization above).
1400    // (Note: any data loss warnings should be suppressed.)
1401    // The exception is the reverse of enum->integer, i.e. integer->enum (and
1402    // enum->enum). See also C++ 5.2.9p7.
1403    // The same goes for reverse floating point promotion/conversion and
1404    // floating-integral conversions. Again, only floating->enum is relevant.
1405    if (DestType->isEnumeralType()) {
1406      if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1407                                   diag::err_bad_cast_incomplete)) {
1408        SrcExpr = ExprError();
1409        return TC_Failed;
1410      }
1411      if (SrcType->isIntegralOrEnumerationType()) {
1412        // [expr.static.cast]p10 If the enumeration type has a fixed underlying
1413        // type, the value is first converted to that type by integral conversion
1414        const EnumType *Enum = DestType->castAs<EnumType>();
1415        Kind = Enum->getDecl()->isFixed() &&
1416                       Enum->getDecl()->getIntegerType()->isBooleanType()
1417                   ? CK_IntegralToBoolean
1418                   : CK_IntegralCast;
1419        return TC_Success;
1420      } else if (SrcType->isRealFloatingType())   {
1421        Kind = CK_FloatingToIntegral;
1422        return TC_Success;
1423      }
1424    }
1425  
1426    // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
1427    // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
1428    tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
1429                                   Kind, BasePath);
1430    if (tcr != TC_NotApplicable)
1431      return tcr;
1432  
1433    // Reverse member pointer conversion. C++ 4.11 specifies member pointer
1434    // conversion. C++ 5.2.9p9 has additional information.
1435    // DR54's access restrictions apply here also.
1436    tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle,
1437                                       OpRange, msg, Kind, BasePath);
1438    if (tcr != TC_NotApplicable)
1439      return tcr;
1440  
1441    // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
1442    // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
1443    // just the usual constness stuff.
1444    if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
1445      QualType SrcPointee = SrcPointer->getPointeeType();
1446      if (SrcPointee->isVoidType()) {
1447        if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
1448          QualType DestPointee = DestPointer->getPointeeType();
1449          if (DestPointee->isIncompleteOrObjectType()) {
1450            // This is definitely the intended conversion, but it might fail due
1451            // to a qualifier violation. Note that we permit Objective-C lifetime
1452            // and GC qualifier mismatches here.
1453            if (!CStyle) {
1454              Qualifiers DestPointeeQuals = DestPointee.getQualifiers();
1455              Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers();
1456              DestPointeeQuals.removeObjCGCAttr();
1457              DestPointeeQuals.removeObjCLifetime();
1458              SrcPointeeQuals.removeObjCGCAttr();
1459              SrcPointeeQuals.removeObjCLifetime();
1460              if (DestPointeeQuals != SrcPointeeQuals &&
1461                  !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) {
1462                msg = diag::err_bad_cxx_cast_qualifiers_away;
1463                return TC_Failed;
1464              }
1465            }
1466            Kind = IsAddressSpaceConversion(SrcType, DestType)
1467                       ? CK_AddressSpaceConversion
1468                       : CK_BitCast;
1469            return TC_Success;
1470          }
1471  
1472          // Microsoft permits static_cast from 'pointer-to-void' to
1473          // 'pointer-to-function'.
1474          if (!CStyle && Self.getLangOpts().MSVCCompat &&
1475              DestPointee->isFunctionType()) {
1476            Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange;
1477            Kind = CK_BitCast;
1478            return TC_Success;
1479          }
1480        }
1481        else if (DestType->isObjCObjectPointerType()) {
1482          // allow both c-style cast and static_cast of objective-c pointers as
1483          // they are pervasive.
1484          Kind = CK_CPointerToObjCPointerCast;
1485          return TC_Success;
1486        }
1487        else if (CStyle && DestType->isBlockPointerType()) {
1488          // allow c-style cast of void * to block pointers.
1489          Kind = CK_AnyPointerToBlockPointerCast;
1490          return TC_Success;
1491        }
1492      }
1493    }
1494    // Allow arbitrary objective-c pointer conversion with static casts.
1495    if (SrcType->isObjCObjectPointerType() &&
1496        DestType->isObjCObjectPointerType()) {
1497      Kind = CK_BitCast;
1498      return TC_Success;
1499    }
1500    // Allow ns-pointer to cf-pointer conversion in either direction
1501    // with static casts.
1502    if (!CStyle &&
1503        Self.ObjC().CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind))
1504      return TC_Success;
1505  
1506    // See if it looks like the user is trying to convert between
1507    // related record types, and select a better diagnostic if so.
1508    if (auto SrcPointer = SrcType->getAs<PointerType>())
1509      if (auto DestPointer = DestType->getAs<PointerType>())
1510        if (SrcPointer->getPointeeType()->getAs<RecordType>() &&
1511            DestPointer->getPointeeType()->getAs<RecordType>())
1512         msg = diag::err_bad_cxx_cast_unrelated_class;
1513  
1514    if (SrcType->isMatrixType() && DestType->isMatrixType()) {
1515      if (Self.CheckMatrixCast(OpRange, DestType, SrcType, Kind)) {
1516        SrcExpr = ExprError();
1517        return TC_Failed;
1518      }
1519      return TC_Success;
1520    }
1521  
1522    // We tried everything. Everything! Nothing works! :-(
1523    return TC_NotApplicable;
1524  }
1525  
1526  /// Tests whether a conversion according to N2844 is valid.
1527  TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
1528                                      QualType DestType, bool CStyle,
1529                                      CastKind &Kind, CXXCastPath &BasePath,
1530                                      unsigned &msg) {
1531    // C++11 [expr.static.cast]p3:
1532    //   A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
1533    //   cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
1534    const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
1535    if (!R)
1536      return TC_NotApplicable;
1537  
1538    if (!SrcExpr->isGLValue())
1539      return TC_NotApplicable;
1540  
1541    // Because we try the reference downcast before this function, from now on
1542    // this is the only cast possibility, so we issue an error if we fail now.
1543    // FIXME: Should allow casting away constness if CStyle.
1544    QualType FromType = SrcExpr->getType();
1545    QualType ToType = R->getPointeeType();
1546    if (CStyle) {
1547      FromType = FromType.getUnqualifiedType();
1548      ToType = ToType.getUnqualifiedType();
1549    }
1550  
1551    Sema::ReferenceConversions RefConv;
1552    Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship(
1553        SrcExpr->getBeginLoc(), ToType, FromType, &RefConv);
1554    if (RefResult != Sema::Ref_Compatible) {
1555      if (CStyle || RefResult == Sema::Ref_Incompatible)
1556        return TC_NotApplicable;
1557      // Diagnose types which are reference-related but not compatible here since
1558      // we can provide better diagnostics. In these cases forwarding to
1559      // [expr.static.cast]p4 should never result in a well-formed cast.
1560      msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast
1561                                : diag::err_bad_rvalue_to_rvalue_cast;
1562      return TC_Failed;
1563    }
1564  
1565    if (RefConv & Sema::ReferenceConversions::DerivedToBase) {
1566      Kind = CK_DerivedToBase;
1567      CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1568                         /*DetectVirtual=*/true);
1569      if (!Self.IsDerivedFrom(SrcExpr->getBeginLoc(), SrcExpr->getType(),
1570                              R->getPointeeType(), Paths))
1571        return TC_NotApplicable;
1572  
1573      Self.BuildBasePathArray(Paths, BasePath);
1574    } else
1575      Kind = CK_NoOp;
1576  
1577    return TC_Success;
1578  }
1579  
1580  /// Tests whether a conversion according to C++ 5.2.9p5 is valid.
1581  TryCastResult
1582  TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
1583                             bool CStyle, SourceRange OpRange,
1584                             unsigned &msg, CastKind &Kind,
1585                             CXXCastPath &BasePath) {
1586    // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
1587    //   cast to type "reference to cv2 D", where D is a class derived from B,
1588    //   if a valid standard conversion from "pointer to D" to "pointer to B"
1589    //   exists, cv2 >= cv1, and B is not a virtual base class of D.
1590    // In addition, DR54 clarifies that the base must be accessible in the
1591    // current context. Although the wording of DR54 only applies to the pointer
1592    // variant of this rule, the intent is clearly for it to apply to the this
1593    // conversion as well.
1594  
1595    const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
1596    if (!DestReference) {
1597      return TC_NotApplicable;
1598    }
1599    bool RValueRef = DestReference->isRValueReferenceType();
1600    if (!RValueRef && !SrcExpr->isLValue()) {
1601      // We know the left side is an lvalue reference, so we can suggest a reason.
1602      msg = diag::err_bad_cxx_cast_rvalue;
1603      return TC_NotApplicable;
1604    }
1605  
1606    QualType DestPointee = DestReference->getPointeeType();
1607  
1608    // FIXME: If the source is a prvalue, we should issue a warning (because the
1609    // cast always has undefined behavior), and for AST consistency, we should
1610    // materialize a temporary.
1611    return TryStaticDowncast(Self,
1612                             Self.Context.getCanonicalType(SrcExpr->getType()),
1613                             Self.Context.getCanonicalType(DestPointee), CStyle,
1614                             OpRange, SrcExpr->getType(), DestType, msg, Kind,
1615                             BasePath);
1616  }
1617  
1618  /// Tests whether a conversion according to C++ 5.2.9p8 is valid.
1619  TryCastResult
1620  TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
1621                           bool CStyle, SourceRange OpRange,
1622                           unsigned &msg, CastKind &Kind,
1623                           CXXCastPath &BasePath) {
1624    // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
1625    //   type, can be converted to an rvalue of type "pointer to cv2 D", where D
1626    //   is a class derived from B, if a valid standard conversion from "pointer
1627    //   to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
1628    //   class of D.
1629    // In addition, DR54 clarifies that the base must be accessible in the
1630    // current context.
1631  
1632    const PointerType *DestPointer = DestType->getAs<PointerType>();
1633    if (!DestPointer) {
1634      return TC_NotApplicable;
1635    }
1636  
1637    const PointerType *SrcPointer = SrcType->getAs<PointerType>();
1638    if (!SrcPointer) {
1639      msg = diag::err_bad_static_cast_pointer_nonpointer;
1640      return TC_NotApplicable;
1641    }
1642  
1643    return TryStaticDowncast(Self,
1644                     Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
1645                    Self.Context.getCanonicalType(DestPointer->getPointeeType()),
1646                             CStyle, OpRange, SrcType, DestType, msg, Kind,
1647                             BasePath);
1648  }
1649  
1650  /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
1651  /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
1652  /// DestType is possible and allowed.
1653  TryCastResult
1654  TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
1655                    bool CStyle, SourceRange OpRange, QualType OrigSrcType,
1656                    QualType OrigDestType, unsigned &msg,
1657                    CastKind &Kind, CXXCastPath &BasePath) {
1658    // We can only work with complete types. But don't complain if it doesn't work
1659    if (!Self.isCompleteType(OpRange.getBegin(), SrcType) ||
1660        !Self.isCompleteType(OpRange.getBegin(), DestType))
1661      return TC_NotApplicable;
1662  
1663    // Downcast can only happen in class hierarchies, so we need classes.
1664    if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
1665      return TC_NotApplicable;
1666    }
1667  
1668    CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1669                       /*DetectVirtual=*/true);
1670    if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) {
1671      return TC_NotApplicable;
1672    }
1673  
1674    // Target type does derive from source type. Now we're serious. If an error
1675    // appears now, it's not ignored.
1676    // This may not be entirely in line with the standard. Take for example:
1677    // struct A {};
1678    // struct B : virtual A {
1679    //   B(A&);
1680    // };
1681    //
1682    // void f()
1683    // {
1684    //   (void)static_cast<const B&>(*((A*)0));
1685    // }
1686    // As far as the standard is concerned, p5 does not apply (A is virtual), so
1687    // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
1688    // However, both GCC and Comeau reject this example, and accepting it would
1689    // mean more complex code if we're to preserve the nice error message.
1690    // FIXME: Being 100% compliant here would be nice to have.
1691  
1692    // Must preserve cv, as always, unless we're in C-style mode.
1693    if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
1694      msg = diag::err_bad_cxx_cast_qualifiers_away;
1695      return TC_Failed;
1696    }
1697  
1698    if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
1699      // This code is analoguous to that in CheckDerivedToBaseConversion, except
1700      // that it builds the paths in reverse order.
1701      // To sum up: record all paths to the base and build a nice string from
1702      // them. Use it to spice up the error message.
1703      if (!Paths.isRecordingPaths()) {
1704        Paths.clear();
1705        Paths.setRecordingPaths(true);
1706        Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths);
1707      }
1708      std::string PathDisplayStr;
1709      std::set<unsigned> DisplayedPaths;
1710      for (clang::CXXBasePath &Path : Paths) {
1711        if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) {
1712          // We haven't displayed a path to this particular base
1713          // class subobject yet.
1714          PathDisplayStr += "\n    ";
1715          for (CXXBasePathElement &PE : llvm::reverse(Path))
1716            PathDisplayStr += PE.Base->getType().getAsString() + " -> ";
1717          PathDisplayStr += QualType(DestType).getAsString();
1718        }
1719      }
1720  
1721      Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
1722        << QualType(SrcType).getUnqualifiedType()
1723        << QualType(DestType).getUnqualifiedType()
1724        << PathDisplayStr << OpRange;
1725      msg = 0;
1726      return TC_Failed;
1727    }
1728  
1729    if (Paths.getDetectedVirtual() != nullptr) {
1730      QualType VirtualBase(Paths.getDetectedVirtual(), 0);
1731      Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
1732        << OrigSrcType << OrigDestType << VirtualBase << OpRange;
1733      msg = 0;
1734      return TC_Failed;
1735    }
1736  
1737    if (!CStyle) {
1738      switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1739                                        SrcType, DestType,
1740                                        Paths.front(),
1741                                  diag::err_downcast_from_inaccessible_base)) {
1742      case Sema::AR_accessible:
1743      case Sema::AR_delayed:     // be optimistic
1744      case Sema::AR_dependent:   // be optimistic
1745        break;
1746  
1747      case Sema::AR_inaccessible:
1748        msg = 0;
1749        return TC_Failed;
1750      }
1751    }
1752  
1753    Self.BuildBasePathArray(Paths, BasePath);
1754    Kind = CK_BaseToDerived;
1755    return TC_Success;
1756  }
1757  
1758  /// TryStaticMemberPointerUpcast - Tests whether a conversion according to
1759  /// C++ 5.2.9p9 is valid:
1760  ///
1761  ///   An rvalue of type "pointer to member of D of type cv1 T" can be
1762  ///   converted to an rvalue of type "pointer to member of B of type cv2 T",
1763  ///   where B is a base class of D [...].
1764  ///
1765  TryCastResult
1766  TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType,
1767                               QualType DestType, bool CStyle,
1768                               SourceRange OpRange,
1769                               unsigned &msg, CastKind &Kind,
1770                               CXXCastPath &BasePath) {
1771    const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
1772    if (!DestMemPtr)
1773      return TC_NotApplicable;
1774  
1775    bool WasOverloadedFunction = false;
1776    DeclAccessPair FoundOverload;
1777    if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1778      if (FunctionDecl *Fn
1779            = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false,
1780                                                      FoundOverload)) {
1781        CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
1782        SrcType = Self.Context.getMemberPointerType(Fn->getType(),
1783                        Self.Context.getTypeDeclType(M->getParent()).getTypePtr());
1784        WasOverloadedFunction = true;
1785      }
1786    }
1787  
1788    const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1789    if (!SrcMemPtr) {
1790      msg = diag::err_bad_static_cast_member_pointer_nonmp;
1791      return TC_NotApplicable;
1792    }
1793  
1794    // Lock down the inheritance model right now in MS ABI, whether or not the
1795    // pointee types are the same.
1796    if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
1797      (void)Self.isCompleteType(OpRange.getBegin(), SrcType);
1798      (void)Self.isCompleteType(OpRange.getBegin(), DestType);
1799    }
1800  
1801    // T == T, modulo cv
1802    if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
1803                                             DestMemPtr->getPointeeType()))
1804      return TC_NotApplicable;
1805  
1806    // B base of D
1807    QualType SrcClass(SrcMemPtr->getClass(), 0);
1808    QualType DestClass(DestMemPtr->getClass(), 0);
1809    CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1810                    /*DetectVirtual=*/true);
1811    if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths))
1812      return TC_NotApplicable;
1813  
1814    // B is a base of D. But is it an allowed base? If not, it's a hard error.
1815    if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) {
1816      Paths.clear();
1817      Paths.setRecordingPaths(true);
1818      bool StillOkay =
1819          Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths);
1820      assert(StillOkay);
1821      (void)StillOkay;
1822      std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
1823      Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
1824        << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
1825      msg = 0;
1826      return TC_Failed;
1827    }
1828  
1829    if (const RecordType *VBase = Paths.getDetectedVirtual()) {
1830      Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
1831        << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
1832      msg = 0;
1833      return TC_Failed;
1834    }
1835  
1836    if (!CStyle) {
1837      switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1838                                        DestClass, SrcClass,
1839                                        Paths.front(),
1840                                        diag::err_upcast_to_inaccessible_base)) {
1841      case Sema::AR_accessible:
1842      case Sema::AR_delayed:
1843      case Sema::AR_dependent:
1844        // Optimistically assume that the delayed and dependent cases
1845        // will work out.
1846        break;
1847  
1848      case Sema::AR_inaccessible:
1849        msg = 0;
1850        return TC_Failed;
1851      }
1852    }
1853  
1854    if (WasOverloadedFunction) {
1855      // Resolve the address of the overloaded function again, this time
1856      // allowing complaints if something goes wrong.
1857      FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
1858                                                                 DestType,
1859                                                                 true,
1860                                                                 FoundOverload);
1861      if (!Fn) {
1862        msg = 0;
1863        return TC_Failed;
1864      }
1865  
1866      SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn);
1867      if (!SrcExpr.isUsable()) {
1868        msg = 0;
1869        return TC_Failed;
1870      }
1871    }
1872  
1873    Self.BuildBasePathArray(Paths, BasePath);
1874    Kind = CK_DerivedToBaseMemberPointer;
1875    return TC_Success;
1876  }
1877  
1878  /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
1879  /// is valid:
1880  ///
1881  ///   An expression e can be explicitly converted to a type T using a
1882  ///   @c static_cast if the declaration "T t(e);" is well-formed [...].
1883  TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
1884                                      QualType DestType,
1885                                      CheckedConversionKind CCK,
1886                                      SourceRange OpRange, unsigned &msg,
1887                                      CastKind &Kind, bool ListInitialization) {
1888    if (DestType->isRecordType()) {
1889      if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1890                                   diag::err_bad_cast_incomplete) ||
1891          Self.RequireNonAbstractType(OpRange.getBegin(), DestType,
1892                                      diag::err_allocation_of_abstract_type)) {
1893        msg = 0;
1894        return TC_Failed;
1895      }
1896    }
1897  
1898    InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType);
1899    InitializationKind InitKind =
1900        (CCK == CheckedConversionKind::CStyleCast)
1901            ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange,
1902                                                   ListInitialization)
1903        : (CCK == CheckedConversionKind::FunctionalCast)
1904            ? InitializationKind::CreateFunctionalCast(OpRange,
1905                                                       ListInitialization)
1906            : InitializationKind::CreateCast(OpRange);
1907    Expr *SrcExprRaw = SrcExpr.get();
1908    // FIXME: Per DR242, we should check for an implicit conversion sequence
1909    // or for a constructor that could be invoked by direct-initialization
1910    // here, not for an initialization sequence.
1911    InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw);
1912  
1913    // At this point of CheckStaticCast, if the destination is a reference,
1914    // or the expression is an overload expression this has to work.
1915    // There is no other way that works.
1916    // On the other hand, if we're checking a C-style cast, we've still got
1917    // the reinterpret_cast way.
1918    bool CStyle = (CCK == CheckedConversionKind::CStyleCast ||
1919                   CCK == CheckedConversionKind::FunctionalCast);
1920    if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType()))
1921      return TC_NotApplicable;
1922  
1923    ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw);
1924    if (Result.isInvalid()) {
1925      msg = 0;
1926      return TC_Failed;
1927    }
1928  
1929    if (InitSeq.isConstructorInitialization())
1930      Kind = CK_ConstructorConversion;
1931    else
1932      Kind = CK_NoOp;
1933  
1934    SrcExpr = Result;
1935    return TC_Success;
1936  }
1937  
1938  /// TryConstCast - See if a const_cast from source to destination is allowed,
1939  /// and perform it if it is.
1940  static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
1941                                    QualType DestType, bool CStyle,
1942                                    unsigned &msg) {
1943    DestType = Self.Context.getCanonicalType(DestType);
1944    QualType SrcType = SrcExpr.get()->getType();
1945    bool NeedToMaterializeTemporary = false;
1946  
1947    if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
1948      // C++11 5.2.11p4:
1949      //   if a pointer to T1 can be explicitly converted to the type "pointer to
1950      //   T2" using a const_cast, then the following conversions can also be
1951      //   made:
1952      //    -- an lvalue of type T1 can be explicitly converted to an lvalue of
1953      //       type T2 using the cast const_cast<T2&>;
1954      //    -- a glvalue of type T1 can be explicitly converted to an xvalue of
1955      //       type T2 using the cast const_cast<T2&&>; and
1956      //    -- if T1 is a class type, a prvalue of type T1 can be explicitly
1957      //       converted to an xvalue of type T2 using the cast const_cast<T2&&>.
1958  
1959      if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) {
1960        // Cannot const_cast non-lvalue to lvalue reference type. But if this
1961        // is C-style, static_cast might find a way, so we simply suggest a
1962        // message and tell the parent to keep searching.
1963        msg = diag::err_bad_cxx_cast_rvalue;
1964        return TC_NotApplicable;
1965      }
1966  
1967      if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isPRValue()) {
1968        if (!SrcType->isRecordType()) {
1969          // Cannot const_cast non-class prvalue to rvalue reference type. But if
1970          // this is C-style, static_cast can do this.
1971          msg = diag::err_bad_cxx_cast_rvalue;
1972          return TC_NotApplicable;
1973        }
1974  
1975        // Materialize the class prvalue so that the const_cast can bind a
1976        // reference to it.
1977        NeedToMaterializeTemporary = true;
1978      }
1979  
1980      // It's not completely clear under the standard whether we can
1981      // const_cast bit-field gl-values.  Doing so would not be
1982      // intrinsically complicated, but for now, we say no for
1983      // consistency with other compilers and await the word of the
1984      // committee.
1985      if (SrcExpr.get()->refersToBitField()) {
1986        msg = diag::err_bad_cxx_cast_bitfield;
1987        return TC_NotApplicable;
1988      }
1989  
1990      DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1991      SrcType = Self.Context.getPointerType(SrcType);
1992    }
1993  
1994    // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
1995    //   the rules for const_cast are the same as those used for pointers.
1996  
1997    if (!DestType->isPointerType() &&
1998        !DestType->isMemberPointerType() &&
1999        !DestType->isObjCObjectPointerType()) {
2000      // Cannot cast to non-pointer, non-reference type. Note that, if DestType
2001      // was a reference type, we converted it to a pointer above.
2002      // The status of rvalue references isn't entirely clear, but it looks like
2003      // conversion to them is simply invalid.
2004      // C++ 5.2.11p3: For two pointer types [...]
2005      if (!CStyle)
2006        msg = diag::err_bad_const_cast_dest;
2007      return TC_NotApplicable;
2008    }
2009    if (DestType->isFunctionPointerType() ||
2010        DestType->isMemberFunctionPointerType()) {
2011      // Cannot cast direct function pointers.
2012      // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
2013      // T is the ultimate pointee of source and target type.
2014      if (!CStyle)
2015        msg = diag::err_bad_const_cast_dest;
2016      return TC_NotApplicable;
2017    }
2018  
2019    // C++ [expr.const.cast]p3:
2020    //   "For two similar types T1 and T2, [...]"
2021    //
2022    // We only allow a const_cast to change cvr-qualifiers, not other kinds of
2023    // type qualifiers. (Likewise, we ignore other changes when determining
2024    // whether a cast casts away constness.)
2025    if (!Self.Context.hasCvrSimilarType(SrcType, DestType))
2026      return TC_NotApplicable;
2027  
2028    if (NeedToMaterializeTemporary)
2029      // This is a const_cast from a class prvalue to an rvalue reference type.
2030      // Materialize a temporary to store the result of the conversion.
2031      SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(),
2032                                                    SrcExpr.get(),
2033                                                    /*IsLValueReference*/ false);
2034  
2035    return TC_Success;
2036  }
2037  
2038  // Checks for undefined behavior in reinterpret_cast.
2039  // The cases that is checked for is:
2040  // *reinterpret_cast<T*>(&a)
2041  // reinterpret_cast<T&>(a)
2042  // where accessing 'a' as type 'T' will result in undefined behavior.
2043  void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
2044                                            bool IsDereference,
2045                                            SourceRange Range) {
2046    unsigned DiagID = IsDereference ?
2047                          diag::warn_pointer_indirection_from_incompatible_type :
2048                          diag::warn_undefined_reinterpret_cast;
2049  
2050    if (Diags.isIgnored(DiagID, Range.getBegin()))
2051      return;
2052  
2053    QualType SrcTy, DestTy;
2054    if (IsDereference) {
2055      if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) {
2056        return;
2057      }
2058      SrcTy = SrcType->getPointeeType();
2059      DestTy = DestType->getPointeeType();
2060    } else {
2061      if (!DestType->getAs<ReferenceType>()) {
2062        return;
2063      }
2064      SrcTy = SrcType;
2065      DestTy = DestType->getPointeeType();
2066    }
2067  
2068    // Cast is compatible if the types are the same.
2069    if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) {
2070      return;
2071    }
2072    // or one of the types is a char or void type
2073    if (DestTy->isAnyCharacterType() || DestTy->isVoidType() ||
2074        SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) {
2075      return;
2076    }
2077    // or one of the types is a tag type.
2078    if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) {
2079      return;
2080    }
2081  
2082    // FIXME: Scoped enums?
2083    if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) ||
2084        (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) {
2085      if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) {
2086        return;
2087      }
2088    }
2089  
2090    Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range;
2091  }
2092  
2093  static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr,
2094                                    QualType DestType) {
2095    QualType SrcType = SrcExpr.get()->getType();
2096    if (Self.Context.hasSameType(SrcType, DestType))
2097      return;
2098    if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>())
2099      if (SrcPtrTy->isObjCSelType()) {
2100        QualType DT = DestType;
2101        if (isa<PointerType>(DestType))
2102          DT = DestType->getPointeeType();
2103        if (!DT.getUnqualifiedType()->isVoidType())
2104          Self.Diag(SrcExpr.get()->getExprLoc(),
2105                    diag::warn_cast_pointer_from_sel)
2106          << SrcType << DestType << SrcExpr.get()->getSourceRange();
2107      }
2108  }
2109  
2110  /// Diagnose casts that change the calling convention of a pointer to a function
2111  /// defined in the current TU.
2112  static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr,
2113                                      QualType DstType, SourceRange OpRange) {
2114    // Check if this cast would change the calling convention of a function
2115    // pointer type.
2116    QualType SrcType = SrcExpr.get()->getType();
2117    if (Self.Context.hasSameType(SrcType, DstType) ||
2118        !SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType())
2119      return;
2120    const auto *SrcFTy =
2121        SrcType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>();
2122    const auto *DstFTy =
2123        DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>();
2124    CallingConv SrcCC = SrcFTy->getCallConv();
2125    CallingConv DstCC = DstFTy->getCallConv();
2126    if (SrcCC == DstCC)
2127      return;
2128  
2129    // We have a calling convention cast. Check if the source is a pointer to a
2130    // known, specific function that has already been defined.
2131    Expr *Src = SrcExpr.get()->IgnoreParenImpCasts();
2132    if (auto *UO = dyn_cast<UnaryOperator>(Src))
2133      if (UO->getOpcode() == UO_AddrOf)
2134        Src = UO->getSubExpr()->IgnoreParenImpCasts();
2135    auto *DRE = dyn_cast<DeclRefExpr>(Src);
2136    if (!DRE)
2137      return;
2138    auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
2139    if (!FD)
2140      return;
2141  
2142    // Only warn if we are casting from the default convention to a non-default
2143    // convention. This can happen when the programmer forgot to apply the calling
2144    // convention to the function declaration and then inserted this cast to
2145    // satisfy the type system.
2146    CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention(
2147        FD->isVariadic(), FD->isCXXInstanceMember());
2148    if (DstCC == DefaultCC || SrcCC != DefaultCC)
2149      return;
2150  
2151    // Diagnose this cast, as it is probably bad.
2152    StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC);
2153    StringRef DstCCName = FunctionType::getNameForCallConv(DstCC);
2154    Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv)
2155        << SrcCCName << DstCCName << OpRange;
2156  
2157    // The checks above are cheaper than checking if the diagnostic is enabled.
2158    // However, it's worth checking if the warning is enabled before we construct
2159    // a fixit.
2160    if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin()))
2161      return;
2162  
2163    // Try to suggest a fixit to change the calling convention of the function
2164    // whose address was taken. Try to use the latest macro for the convention.
2165    // For example, users probably want to write "WINAPI" instead of "__stdcall"
2166    // to match the Windows header declarations.
2167    SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc();
2168    Preprocessor &PP = Self.getPreprocessor();
2169    SmallVector<TokenValue, 6> AttrTokens;
2170    SmallString<64> CCAttrText;
2171    llvm::raw_svector_ostream OS(CCAttrText);
2172    if (Self.getLangOpts().MicrosoftExt) {
2173      // __stdcall or __vectorcall
2174      OS << "__" << DstCCName;
2175      IdentifierInfo *II = PP.getIdentifierInfo(OS.str());
2176      AttrTokens.push_back(II->isKeyword(Self.getLangOpts())
2177                               ? TokenValue(II->getTokenID())
2178                               : TokenValue(II));
2179    } else {
2180      // __attribute__((stdcall)) or __attribute__((vectorcall))
2181      OS << "__attribute__((" << DstCCName << "))";
2182      AttrTokens.push_back(tok::kw___attribute);
2183      AttrTokens.push_back(tok::l_paren);
2184      AttrTokens.push_back(tok::l_paren);
2185      IdentifierInfo *II = PP.getIdentifierInfo(DstCCName);
2186      AttrTokens.push_back(II->isKeyword(Self.getLangOpts())
2187                               ? TokenValue(II->getTokenID())
2188                               : TokenValue(II));
2189      AttrTokens.push_back(tok::r_paren);
2190      AttrTokens.push_back(tok::r_paren);
2191    }
2192    StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens);
2193    if (!AttrSpelling.empty())
2194      CCAttrText = AttrSpelling;
2195    OS << ' ';
2196    Self.Diag(NameLoc, diag::note_change_calling_conv_fixit)
2197        << FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText);
2198  }
2199  
2200  static void checkIntToPointerCast(bool CStyle, const SourceRange &OpRange,
2201                                    const Expr *SrcExpr, QualType DestType,
2202                                    Sema &Self) {
2203    QualType SrcType = SrcExpr->getType();
2204  
2205    // Not warning on reinterpret_cast, boolean, constant expressions, etc
2206    // are not explicit design choices, but consistent with GCC's behavior.
2207    // Feel free to modify them if you've reason/evidence for an alternative.
2208    if (CStyle && SrcType->isIntegralType(Self.Context)
2209        && !SrcType->isBooleanType()
2210        && !SrcType->isEnumeralType()
2211        && !SrcExpr->isIntegerConstantExpr(Self.Context)
2212        && Self.Context.getTypeSize(DestType) >
2213           Self.Context.getTypeSize(SrcType)) {
2214      // Separate between casts to void* and non-void* pointers.
2215      // Some APIs use (abuse) void* for something like a user context,
2216      // and often that value is an integer even if it isn't a pointer itself.
2217      // Having a separate warning flag allows users to control the warning
2218      // for their workflow.
2219      unsigned Diag = DestType->isVoidPointerType() ?
2220                        diag::warn_int_to_void_pointer_cast
2221                      : diag::warn_int_to_pointer_cast;
2222      Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
2223    }
2224  }
2225  
2226  static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType,
2227                                               ExprResult &Result) {
2228    // We can only fix an overloaded reinterpret_cast if
2229    // - it is a template with explicit arguments that resolves to an lvalue
2230    //   unambiguously, or
2231    // - it is the only function in an overload set that may have its address
2232    //   taken.
2233  
2234    Expr *E = Result.get();
2235    // TODO: what if this fails because of DiagnoseUseOfDecl or something
2236    // like it?
2237    if (Self.ResolveAndFixSingleFunctionTemplateSpecialization(
2238            Result,
2239            Expr::getValueKindForType(DestType) ==
2240                VK_PRValue // Convert Fun to Ptr
2241            ) &&
2242        Result.isUsable())
2243      return true;
2244  
2245    // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization
2246    // preserves Result.
2247    Result = E;
2248    if (!Self.resolveAndFixAddressOfSingleOverloadCandidate(
2249            Result, /*DoFunctionPointerConversion=*/true))
2250      return false;
2251    return Result.isUsable();
2252  }
2253  
2254  static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
2255                                          QualType DestType, bool CStyle,
2256                                          SourceRange OpRange,
2257                                          unsigned &msg,
2258                                          CastKind &Kind) {
2259    bool IsLValueCast = false;
2260  
2261    DestType = Self.Context.getCanonicalType(DestType);
2262    QualType SrcType = SrcExpr.get()->getType();
2263  
2264    // Is the source an overloaded name? (i.e. &foo)
2265    // If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5)
2266    if (SrcType == Self.Context.OverloadTy) {
2267      ExprResult FixedExpr = SrcExpr;
2268      if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr))
2269        return TC_NotApplicable;
2270  
2271      assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr");
2272      SrcExpr = FixedExpr;
2273      SrcType = SrcExpr.get()->getType();
2274    }
2275  
2276    if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
2277      if (!SrcExpr.get()->isGLValue()) {
2278        // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the
2279        // similar comment in const_cast.
2280        msg = diag::err_bad_cxx_cast_rvalue;
2281        return TC_NotApplicable;
2282      }
2283  
2284      if (!CStyle) {
2285        Self.CheckCompatibleReinterpretCast(SrcType, DestType,
2286                                            /*IsDereference=*/false, OpRange);
2287      }
2288  
2289      // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
2290      //   same effect as the conversion *reinterpret_cast<T*>(&x) with the
2291      //   built-in & and * operators.
2292  
2293      const char *inappropriate = nullptr;
2294      switch (SrcExpr.get()->getObjectKind()) {
2295      case OK_Ordinary:
2296        break;
2297      case OK_BitField:
2298        msg = diag::err_bad_cxx_cast_bitfield;
2299        return TC_NotApplicable;
2300        // FIXME: Use a specific diagnostic for the rest of these cases.
2301      case OK_VectorComponent: inappropriate = "vector element";      break;
2302      case OK_MatrixComponent:
2303        inappropriate = "matrix element";
2304        break;
2305      case OK_ObjCProperty:    inappropriate = "property expression"; break;
2306      case OK_ObjCSubscript:   inappropriate = "container subscripting expression";
2307                               break;
2308      }
2309      if (inappropriate) {
2310        Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
2311            << inappropriate << DestType
2312            << OpRange << SrcExpr.get()->getSourceRange();
2313        msg = 0; SrcExpr = ExprError();
2314        return TC_NotApplicable;
2315      }
2316  
2317      // This code does this transformation for the checked types.
2318      DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
2319      SrcType = Self.Context.getPointerType(SrcType);
2320  
2321      IsLValueCast = true;
2322    }
2323  
2324    // Canonicalize source for comparison.
2325    SrcType = Self.Context.getCanonicalType(SrcType);
2326  
2327    const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
2328                            *SrcMemPtr = SrcType->getAs<MemberPointerType>();
2329    if (DestMemPtr && SrcMemPtr) {
2330      // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
2331      //   can be explicitly converted to an rvalue of type "pointer to member
2332      //   of Y of type T2" if T1 and T2 are both function types or both object
2333      //   types.
2334      if (DestMemPtr->isMemberFunctionPointer() !=
2335          SrcMemPtr->isMemberFunctionPointer())
2336        return TC_NotApplicable;
2337  
2338      if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
2339        // We need to determine the inheritance model that the class will use if
2340        // haven't yet.
2341        (void)Self.isCompleteType(OpRange.getBegin(), SrcType);
2342        (void)Self.isCompleteType(OpRange.getBegin(), DestType);
2343      }
2344  
2345      // Don't allow casting between member pointers of different sizes.
2346      if (Self.Context.getTypeSize(DestMemPtr) !=
2347          Self.Context.getTypeSize(SrcMemPtr)) {
2348        msg = diag::err_bad_cxx_cast_member_pointer_size;
2349        return TC_Failed;
2350      }
2351  
2352      // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
2353      //   constness.
2354      // A reinterpret_cast followed by a const_cast can, though, so in C-style,
2355      // we accept it.
2356      if (auto CACK =
2357              CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
2358                                 /*CheckObjCLifetime=*/CStyle))
2359        return getCastAwayConstnessCastKind(CACK, msg);
2360  
2361      // A valid member pointer cast.
2362      assert(!IsLValueCast);
2363      Kind = CK_ReinterpretMemberPointer;
2364      return TC_Success;
2365    }
2366  
2367    // See below for the enumeral issue.
2368    if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) {
2369      // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
2370      //   type large enough to hold it. A value of std::nullptr_t can be
2371      //   converted to an integral type; the conversion has the same meaning
2372      //   and validity as a conversion of (void*)0 to the integral type.
2373      if (Self.Context.getTypeSize(SrcType) >
2374          Self.Context.getTypeSize(DestType)) {
2375        msg = diag::err_bad_reinterpret_cast_small_int;
2376        return TC_Failed;
2377      }
2378      Kind = CK_PointerToIntegral;
2379      return TC_Success;
2380    }
2381  
2382    // Allow reinterpret_casts between vectors of the same size and
2383    // between vectors and integers of the same size.
2384    bool destIsVector = DestType->isVectorType();
2385    bool srcIsVector = SrcType->isVectorType();
2386    if (srcIsVector || destIsVector) {
2387      // Allow bitcasting between SVE VLATs and VLSTs, and vice-versa.
2388      if (Self.isValidSveBitcast(SrcType, DestType)) {
2389        Kind = CK_BitCast;
2390        return TC_Success;
2391      }
2392  
2393      // Allow bitcasting between SVE VLATs and VLSTs, and vice-versa.
2394      if (Self.RISCV().isValidRVVBitcast(SrcType, DestType)) {
2395        Kind = CK_BitCast;
2396        return TC_Success;
2397      }
2398  
2399      // The non-vector type, if any, must have integral type.  This is
2400      // the same rule that C vector casts use; note, however, that enum
2401      // types are not integral in C++.
2402      if ((!destIsVector && !DestType->isIntegralType(Self.Context)) ||
2403          (!srcIsVector && !SrcType->isIntegralType(Self.Context)))
2404        return TC_NotApplicable;
2405  
2406      // The size we want to consider is eltCount * eltSize.
2407      // That's exactly what the lax-conversion rules will check.
2408      if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) {
2409        Kind = CK_BitCast;
2410        return TC_Success;
2411      }
2412  
2413      if (Self.LangOpts.OpenCL && !CStyle) {
2414        if (DestType->isExtVectorType() || SrcType->isExtVectorType()) {
2415          // FIXME: Allow for reinterpret cast between 3 and 4 element vectors
2416          if (Self.areVectorTypesSameSize(SrcType, DestType)) {
2417            Kind = CK_BitCast;
2418            return TC_Success;
2419          }
2420        }
2421      }
2422  
2423      // Otherwise, pick a reasonable diagnostic.
2424      if (!destIsVector)
2425        msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
2426      else if (!srcIsVector)
2427        msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
2428      else
2429        msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
2430  
2431      return TC_Failed;
2432    }
2433  
2434    if (SrcType == DestType) {
2435      // C++ 5.2.10p2 has a note that mentions that, subject to all other
2436      // restrictions, a cast to the same type is allowed so long as it does not
2437      // cast away constness. In C++98, the intent was not entirely clear here,
2438      // since all other paragraphs explicitly forbid casts to the same type.
2439      // C++11 clarifies this case with p2.
2440      //
2441      // The only allowed types are: integral, enumeration, pointer, or
2442      // pointer-to-member types.  We also won't restrict Obj-C pointers either.
2443      Kind = CK_NoOp;
2444      TryCastResult Result = TC_NotApplicable;
2445      if (SrcType->isIntegralOrEnumerationType() ||
2446          SrcType->isAnyPointerType() ||
2447          SrcType->isMemberPointerType() ||
2448          SrcType->isBlockPointerType()) {
2449        Result = TC_Success;
2450      }
2451      return Result;
2452    }
2453  
2454    bool destIsPtr = DestType->isAnyPointerType() ||
2455                     DestType->isBlockPointerType();
2456    bool srcIsPtr = SrcType->isAnyPointerType() ||
2457                    SrcType->isBlockPointerType();
2458    if (!destIsPtr && !srcIsPtr) {
2459      // Except for std::nullptr_t->integer and lvalue->reference, which are
2460      // handled above, at least one of the two arguments must be a pointer.
2461      return TC_NotApplicable;
2462    }
2463  
2464    if (DestType->isIntegralType(Self.Context)) {
2465      assert(srcIsPtr && "One type must be a pointer");
2466      // C++ 5.2.10p4: A pointer can be explicitly converted to any integral
2467      //   type large enough to hold it; except in Microsoft mode, where the
2468      //   integral type size doesn't matter (except we don't allow bool).
2469      if ((Self.Context.getTypeSize(SrcType) >
2470           Self.Context.getTypeSize(DestType))) {
2471        bool MicrosoftException =
2472            Self.getLangOpts().MicrosoftExt && !DestType->isBooleanType();
2473        if (MicrosoftException) {
2474          unsigned Diag = SrcType->isVoidPointerType()
2475                              ? diag::warn_void_pointer_to_int_cast
2476                              : diag::warn_pointer_to_int_cast;
2477          Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
2478        } else {
2479          msg = diag::err_bad_reinterpret_cast_small_int;
2480          return TC_Failed;
2481        }
2482      }
2483      Kind = CK_PointerToIntegral;
2484      return TC_Success;
2485    }
2486  
2487    if (SrcType->isIntegralOrEnumerationType()) {
2488      assert(destIsPtr && "One type must be a pointer");
2489      checkIntToPointerCast(CStyle, OpRange, SrcExpr.get(), DestType, Self);
2490      // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
2491      //   converted to a pointer.
2492      // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
2493      //   necessarily converted to a null pointer value.]
2494      Kind = CK_IntegralToPointer;
2495      return TC_Success;
2496    }
2497  
2498    if (!destIsPtr || !srcIsPtr) {
2499      // With the valid non-pointer conversions out of the way, we can be even
2500      // more stringent.
2501      return TC_NotApplicable;
2502    }
2503  
2504    // Cannot convert between block pointers and Objective-C object pointers.
2505    if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) ||
2506        (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType()))
2507      return TC_NotApplicable;
2508  
2509    // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
2510    // The C-style cast operator can.
2511    TryCastResult SuccessResult = TC_Success;
2512    if (auto CACK =
2513            CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
2514                               /*CheckObjCLifetime=*/CStyle))
2515      SuccessResult = getCastAwayConstnessCastKind(CACK, msg);
2516  
2517    if (IsAddressSpaceConversion(SrcType, DestType)) {
2518      Kind = CK_AddressSpaceConversion;
2519      assert(SrcType->isPointerType() && DestType->isPointerType());
2520      if (!CStyle &&
2521          !DestType->getPointeeType().getQualifiers().isAddressSpaceSupersetOf(
2522              SrcType->getPointeeType().getQualifiers())) {
2523        SuccessResult = TC_Failed;
2524      }
2525    } else if (IsLValueCast) {
2526      Kind = CK_LValueBitCast;
2527    } else if (DestType->isObjCObjectPointerType()) {
2528      Kind = Self.ObjC().PrepareCastToObjCObjectPointer(SrcExpr);
2529    } else if (DestType->isBlockPointerType()) {
2530      if (!SrcType->isBlockPointerType()) {
2531        Kind = CK_AnyPointerToBlockPointerCast;
2532      } else {
2533        Kind = CK_BitCast;
2534      }
2535    } else {
2536      Kind = CK_BitCast;
2537    }
2538  
2539    // Any pointer can be cast to an Objective-C pointer type with a C-style
2540    // cast.
2541    if (CStyle && DestType->isObjCObjectPointerType()) {
2542      return SuccessResult;
2543    }
2544    if (CStyle)
2545      DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2546  
2547    DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange);
2548  
2549    // Not casting away constness, so the only remaining check is for compatible
2550    // pointer categories.
2551  
2552    if (SrcType->isFunctionPointerType()) {
2553      if (DestType->isFunctionPointerType()) {
2554        // C++ 5.2.10p6: A pointer to a function can be explicitly converted to
2555        // a pointer to a function of a different type.
2556        return SuccessResult;
2557      }
2558  
2559      // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
2560      //   an object type or vice versa is conditionally-supported.
2561      // Compilers support it in C++03 too, though, because it's necessary for
2562      // casting the return value of dlsym() and GetProcAddress().
2563      // FIXME: Conditionally-supported behavior should be configurable in the
2564      // TargetInfo or similar.
2565      Self.Diag(OpRange.getBegin(),
2566                Self.getLangOpts().CPlusPlus11 ?
2567                  diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2568        << OpRange;
2569      return SuccessResult;
2570    }
2571  
2572    if (DestType->isFunctionPointerType()) {
2573      // See above.
2574      Self.Diag(OpRange.getBegin(),
2575                Self.getLangOpts().CPlusPlus11 ?
2576                  diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2577        << OpRange;
2578      return SuccessResult;
2579    }
2580  
2581    // Diagnose address space conversion in nested pointers.
2582    QualType DestPtee = DestType->getPointeeType().isNull()
2583                            ? DestType->getPointeeType()
2584                            : DestType->getPointeeType()->getPointeeType();
2585    QualType SrcPtee = SrcType->getPointeeType().isNull()
2586                           ? SrcType->getPointeeType()
2587                           : SrcType->getPointeeType()->getPointeeType();
2588    while (!DestPtee.isNull() && !SrcPtee.isNull()) {
2589      if (DestPtee.getAddressSpace() != SrcPtee.getAddressSpace()) {
2590        Self.Diag(OpRange.getBegin(),
2591                  diag::warn_bad_cxx_cast_nested_pointer_addr_space)
2592            << CStyle << SrcType << DestType << SrcExpr.get()->getSourceRange();
2593        break;
2594      }
2595      DestPtee = DestPtee->getPointeeType();
2596      SrcPtee = SrcPtee->getPointeeType();
2597    }
2598  
2599    // C++ 5.2.10p7: A pointer to an object can be explicitly converted to
2600    //   a pointer to an object of different type.
2601    // Void pointers are not specified, but supported by every compiler out there.
2602    // So we finish by allowing everything that remains - it's got to be two
2603    // object pointers.
2604    return SuccessResult;
2605  }
2606  
2607  static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr,
2608                                           QualType DestType, bool CStyle,
2609                                           unsigned &msg, CastKind &Kind) {
2610    if (!Self.getLangOpts().OpenCL && !Self.getLangOpts().SYCLIsDevice)
2611      // FIXME: As compiler doesn't have any information about overlapping addr
2612      // spaces at the moment we have to be permissive here.
2613      return TC_NotApplicable;
2614    // Even though the logic below is general enough and can be applied to
2615    // non-OpenCL mode too, we fast-path above because no other languages
2616    // define overlapping address spaces currently.
2617    auto SrcType = SrcExpr.get()->getType();
2618    // FIXME: Should this be generalized to references? The reference parameter
2619    // however becomes a reference pointee type here and therefore rejected.
2620    // Perhaps this is the right behavior though according to C++.
2621    auto SrcPtrType = SrcType->getAs<PointerType>();
2622    if (!SrcPtrType)
2623      return TC_NotApplicable;
2624    auto DestPtrType = DestType->getAs<PointerType>();
2625    if (!DestPtrType)
2626      return TC_NotApplicable;
2627    auto SrcPointeeType = SrcPtrType->getPointeeType();
2628    auto DestPointeeType = DestPtrType->getPointeeType();
2629    if (!DestPointeeType.isAddressSpaceOverlapping(SrcPointeeType)) {
2630      msg = diag::err_bad_cxx_cast_addr_space_mismatch;
2631      return TC_Failed;
2632    }
2633    auto SrcPointeeTypeWithoutAS =
2634        Self.Context.removeAddrSpaceQualType(SrcPointeeType.getCanonicalType());
2635    auto DestPointeeTypeWithoutAS =
2636        Self.Context.removeAddrSpaceQualType(DestPointeeType.getCanonicalType());
2637    if (Self.Context.hasSameType(SrcPointeeTypeWithoutAS,
2638                                 DestPointeeTypeWithoutAS)) {
2639      Kind = SrcPointeeType.getAddressSpace() == DestPointeeType.getAddressSpace()
2640                 ? CK_NoOp
2641                 : CK_AddressSpaceConversion;
2642      return TC_Success;
2643    } else {
2644      return TC_NotApplicable;
2645    }
2646  }
2647  
2648  void CastOperation::checkAddressSpaceCast(QualType SrcType, QualType DestType) {
2649    // In OpenCL only conversions between pointers to objects in overlapping
2650    // addr spaces are allowed. v2.0 s6.5.5 - Generic addr space overlaps
2651    // with any named one, except for constant.
2652  
2653    // Converting the top level pointee addrspace is permitted for compatible
2654    // addrspaces (such as 'generic int *' to 'local int *' or vice versa), but
2655    // if any of the nested pointee addrspaces differ, we emit a warning
2656    // regardless of addrspace compatibility. This makes
2657    //   local int ** p;
2658    //   return (generic int **) p;
2659    // warn even though local -> generic is permitted.
2660    if (Self.getLangOpts().OpenCL) {
2661      const Type *DestPtr, *SrcPtr;
2662      bool Nested = false;
2663      unsigned DiagID = diag::err_typecheck_incompatible_address_space;
2664      DestPtr = Self.getASTContext().getCanonicalType(DestType.getTypePtr()),
2665      SrcPtr  = Self.getASTContext().getCanonicalType(SrcType.getTypePtr());
2666  
2667      while (isa<PointerType>(DestPtr) && isa<PointerType>(SrcPtr)) {
2668        const PointerType *DestPPtr = cast<PointerType>(DestPtr);
2669        const PointerType *SrcPPtr = cast<PointerType>(SrcPtr);
2670        QualType DestPPointee = DestPPtr->getPointeeType();
2671        QualType SrcPPointee = SrcPPtr->getPointeeType();
2672        if (Nested
2673                ? DestPPointee.getAddressSpace() != SrcPPointee.getAddressSpace()
2674                : !DestPPointee.isAddressSpaceOverlapping(SrcPPointee)) {
2675          Self.Diag(OpRange.getBegin(), DiagID)
2676              << SrcType << DestType << Sema::AA_Casting
2677              << SrcExpr.get()->getSourceRange();
2678          if (!Nested)
2679            SrcExpr = ExprError();
2680          return;
2681        }
2682  
2683        DestPtr = DestPPtr->getPointeeType().getTypePtr();
2684        SrcPtr = SrcPPtr->getPointeeType().getTypePtr();
2685        Nested = true;
2686        DiagID = diag::ext_nested_pointer_qualifier_mismatch;
2687      }
2688    }
2689  }
2690  
2691  bool Sema::ShouldSplatAltivecScalarInCast(const VectorType *VecTy) {
2692    bool SrcCompatXL = this->getLangOpts().getAltivecSrcCompat() ==
2693                       LangOptions::AltivecSrcCompatKind::XL;
2694    VectorKind VKind = VecTy->getVectorKind();
2695  
2696    if ((VKind == VectorKind::AltiVecVector) ||
2697        (SrcCompatXL && ((VKind == VectorKind::AltiVecBool) ||
2698                         (VKind == VectorKind::AltiVecPixel)))) {
2699      return true;
2700    }
2701    return false;
2702  }
2703  
2704  bool Sema::CheckAltivecInitFromScalar(SourceRange R, QualType VecTy,
2705                                        QualType SrcTy) {
2706    bool SrcCompatGCC = this->getLangOpts().getAltivecSrcCompat() ==
2707                        LangOptions::AltivecSrcCompatKind::GCC;
2708    if (this->getLangOpts().AltiVec && SrcCompatGCC) {
2709      this->Diag(R.getBegin(),
2710                 diag::err_invalid_conversion_between_vector_and_integer)
2711          << VecTy << SrcTy << R;
2712      return true;
2713    }
2714    return false;
2715  }
2716  
2717  void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
2718                                         bool ListInitialization) {
2719    assert(Self.getLangOpts().CPlusPlus);
2720  
2721    // Handle placeholders.
2722    if (isPlaceholder()) {
2723      // C-style casts can resolve __unknown_any types.
2724      if (claimPlaceholder(BuiltinType::UnknownAny)) {
2725        SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2726                                           SrcExpr.get(), Kind,
2727                                           ValueKind, BasePath);
2728        return;
2729      }
2730  
2731      checkNonOverloadPlaceholders();
2732      if (SrcExpr.isInvalid())
2733        return;
2734    }
2735  
2736    // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
2737    // This test is outside everything else because it's the only case where
2738    // a non-lvalue-reference target type does not lead to decay.
2739    if (DestType->isVoidType()) {
2740      Kind = CK_ToVoid;
2741  
2742      if (claimPlaceholder(BuiltinType::Overload)) {
2743        Self.ResolveAndFixSingleFunctionTemplateSpecialization(
2744                    SrcExpr, /* Decay Function to ptr */ false,
2745                    /* Complain */ true, DestRange, DestType,
2746                    diag::err_bad_cstyle_cast_overload);
2747        if (SrcExpr.isInvalid())
2748          return;
2749      }
2750  
2751      SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2752      return;
2753    }
2754  
2755    // If the type is dependent, we won't do any other semantic analysis now.
2756    if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() ||
2757        SrcExpr.get()->isValueDependent()) {
2758      assert(Kind == CK_Dependent);
2759      return;
2760    }
2761  
2762    if (ValueKind == VK_PRValue && !DestType->isRecordType() &&
2763        !isPlaceholder(BuiltinType::Overload)) {
2764      SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2765      if (SrcExpr.isInvalid())
2766        return;
2767    }
2768  
2769    // AltiVec vector initialization with a single literal.
2770    if (const VectorType *vecTy = DestType->getAs<VectorType>()) {
2771      if (Self.CheckAltivecInitFromScalar(OpRange, DestType,
2772                                          SrcExpr.get()->getType())) {
2773        SrcExpr = ExprError();
2774        return;
2775      }
2776      if (Self.ShouldSplatAltivecScalarInCast(vecTy) &&
2777          (SrcExpr.get()->getType()->isIntegerType() ||
2778           SrcExpr.get()->getType()->isFloatingType())) {
2779        Kind = CK_VectorSplat;
2780        SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get());
2781        return;
2782      }
2783    }
2784  
2785    // WebAssembly tables cannot be cast.
2786    QualType SrcType = SrcExpr.get()->getType();
2787    if (SrcType->isWebAssemblyTableType()) {
2788      Self.Diag(OpRange.getBegin(), diag::err_wasm_cast_table)
2789          << 1 << SrcExpr.get()->getSourceRange();
2790      SrcExpr = ExprError();
2791      return;
2792    }
2793  
2794    // C++ [expr.cast]p5: The conversions performed by
2795    //   - a const_cast,
2796    //   - a static_cast,
2797    //   - a static_cast followed by a const_cast,
2798    //   - a reinterpret_cast, or
2799    //   - a reinterpret_cast followed by a const_cast,
2800    //   can be performed using the cast notation of explicit type conversion.
2801    //   [...] If a conversion can be interpreted in more than one of the ways
2802    //   listed above, the interpretation that appears first in the list is used,
2803    //   even if a cast resulting from that interpretation is ill-formed.
2804    // In plain language, this means trying a const_cast ...
2805    // Note that for address space we check compatibility after const_cast.
2806    unsigned msg = diag::err_bad_cxx_cast_generic;
2807    TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType,
2808                                     /*CStyle*/ true, msg);
2809    if (SrcExpr.isInvalid())
2810      return;
2811    if (isValidCast(tcr))
2812      Kind = CK_NoOp;
2813  
2814    CheckedConversionKind CCK = FunctionalStyle
2815                                    ? CheckedConversionKind::FunctionalCast
2816                                    : CheckedConversionKind::CStyleCast;
2817    if (tcr == TC_NotApplicable) {
2818      tcr = TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ true, msg,
2819                                Kind);
2820      if (SrcExpr.isInvalid())
2821        return;
2822  
2823      if (tcr == TC_NotApplicable) {
2824        // ... or if that is not possible, a static_cast, ignoring const and
2825        // addr space, ...
2826        tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, msg, Kind,
2827                            BasePath, ListInitialization);
2828        if (SrcExpr.isInvalid())
2829          return;
2830  
2831        if (tcr == TC_NotApplicable) {
2832          // ... and finally a reinterpret_cast, ignoring const and addr space.
2833          tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/ true,
2834                                   OpRange, msg, Kind);
2835          if (SrcExpr.isInvalid())
2836            return;
2837        }
2838      }
2839    }
2840  
2841    if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
2842        isValidCast(tcr))
2843      checkObjCConversion(CCK);
2844  
2845    if (tcr != TC_Success && msg != 0) {
2846      if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2847        DeclAccessPair Found;
2848        FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
2849                                  DestType,
2850                                  /*Complain*/ true,
2851                                  Found);
2852        if (Fn) {
2853          // If DestType is a function type (not to be confused with the function
2854          // pointer type), it will be possible to resolve the function address,
2855          // but the type cast should be considered as failure.
2856          OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression;
2857          Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload)
2858            << OE->getName() << DestType << OpRange
2859            << OE->getQualifierLoc().getSourceRange();
2860          Self.NoteAllOverloadCandidates(SrcExpr.get());
2861        }
2862      } else {
2863        diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle),
2864                        OpRange, SrcExpr.get(), DestType, ListInitialization);
2865      }
2866    }
2867  
2868    if (isValidCast(tcr)) {
2869      if (Kind == CK_BitCast)
2870        checkCastAlign();
2871  
2872      if (unsigned DiagID = checkCastFunctionType(Self, SrcExpr, DestType))
2873        Self.Diag(OpRange.getBegin(), DiagID)
2874            << SrcExpr.get()->getType() << DestType << OpRange;
2875  
2876    } else {
2877      SrcExpr = ExprError();
2878    }
2879  }
2880  
2881  /// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a
2882  ///  non-matching type. Such as enum function call to int, int call to
2883  /// pointer; etc. Cast to 'void' is an exception.
2884  static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr,
2885                                    QualType DestType) {
2886    if (Self.Diags.isIgnored(diag::warn_bad_function_cast,
2887                             SrcExpr.get()->getExprLoc()))
2888      return;
2889  
2890    if (!isa<CallExpr>(SrcExpr.get()))
2891      return;
2892  
2893    QualType SrcType = SrcExpr.get()->getType();
2894    if (DestType.getUnqualifiedType()->isVoidType())
2895      return;
2896    if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType())
2897        && (DestType->isAnyPointerType() || DestType->isBlockPointerType()))
2898      return;
2899    if (SrcType->isIntegerType() && DestType->isIntegerType() &&
2900        (SrcType->isBooleanType() == DestType->isBooleanType()) &&
2901        (SrcType->isEnumeralType() == DestType->isEnumeralType()))
2902      return;
2903    if (SrcType->isRealFloatingType() && DestType->isRealFloatingType())
2904      return;
2905    if (SrcType->isEnumeralType() && DestType->isEnumeralType())
2906      return;
2907    if (SrcType->isComplexType() && DestType->isComplexType())
2908      return;
2909    if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType())
2910      return;
2911    if (SrcType->isFixedPointType() && DestType->isFixedPointType())
2912      return;
2913  
2914    Self.Diag(SrcExpr.get()->getExprLoc(),
2915              diag::warn_bad_function_cast)
2916              << SrcType << DestType << SrcExpr.get()->getSourceRange();
2917  }
2918  
2919  /// Check the semantics of a C-style cast operation, in C.
2920  void CastOperation::CheckCStyleCast() {
2921    assert(!Self.getLangOpts().CPlusPlus);
2922  
2923    // C-style casts can resolve __unknown_any types.
2924    if (claimPlaceholder(BuiltinType::UnknownAny)) {
2925      SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2926                                         SrcExpr.get(), Kind,
2927                                         ValueKind, BasePath);
2928      return;
2929    }
2930  
2931    // C99 6.5.4p2: the cast type needs to be void or scalar and the expression
2932    // type needs to be scalar.
2933    if (DestType->isVoidType()) {
2934      // We don't necessarily do lvalue-to-rvalue conversions on this.
2935      SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2936      if (SrcExpr.isInvalid())
2937        return;
2938  
2939      // Cast to void allows any expr type.
2940      Kind = CK_ToVoid;
2941      return;
2942    }
2943  
2944    // If the type is dependent, we won't do any other semantic analysis now.
2945    if (Self.getASTContext().isDependenceAllowed() &&
2946        (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() ||
2947         SrcExpr.get()->isValueDependent())) {
2948      assert((DestType->containsErrors() || SrcExpr.get()->containsErrors() ||
2949              SrcExpr.get()->containsErrors()) &&
2950             "should only occur in error-recovery path.");
2951      assert(Kind == CK_Dependent);
2952      return;
2953    }
2954  
2955    // Overloads are allowed with C extensions, so we need to support them.
2956    if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2957      DeclAccessPair DAP;
2958      if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction(
2959              SrcExpr.get(), DestType, /*Complain=*/true, DAP))
2960        SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD);
2961      else
2962        return;
2963      assert(SrcExpr.isUsable());
2964    }
2965    SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2966    if (SrcExpr.isInvalid())
2967      return;
2968    QualType SrcType = SrcExpr.get()->getType();
2969  
2970    if (SrcType->isWebAssemblyTableType()) {
2971      Self.Diag(OpRange.getBegin(), diag::err_wasm_cast_table)
2972          << 1 << SrcExpr.get()->getSourceRange();
2973      SrcExpr = ExprError();
2974      return;
2975    }
2976  
2977    assert(!SrcType->isPlaceholderType());
2978  
2979    checkAddressSpaceCast(SrcType, DestType);
2980    if (SrcExpr.isInvalid())
2981      return;
2982  
2983    if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
2984                                 diag::err_typecheck_cast_to_incomplete)) {
2985      SrcExpr = ExprError();
2986      return;
2987    }
2988  
2989    // Allow casting a sizeless built-in type to itself.
2990    if (DestType->isSizelessBuiltinType() &&
2991        Self.Context.hasSameUnqualifiedType(DestType, SrcType)) {
2992      Kind = CK_NoOp;
2993      return;
2994    }
2995  
2996    // Allow bitcasting between compatible SVE vector types.
2997    if ((SrcType->isVectorType() || DestType->isVectorType()) &&
2998        Self.isValidSveBitcast(SrcType, DestType)) {
2999      Kind = CK_BitCast;
3000      return;
3001    }
3002  
3003    // Allow bitcasting between compatible RVV vector types.
3004    if ((SrcType->isVectorType() || DestType->isVectorType()) &&
3005        Self.RISCV().isValidRVVBitcast(SrcType, DestType)) {
3006      Kind = CK_BitCast;
3007      return;
3008    }
3009  
3010    if (!DestType->isScalarType() && !DestType->isVectorType() &&
3011        !DestType->isMatrixType()) {
3012      const RecordType *DestRecordTy = DestType->getAs<RecordType>();
3013  
3014      if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){
3015        // GCC struct/union extension: allow cast to self.
3016        Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar)
3017          << DestType << SrcExpr.get()->getSourceRange();
3018        Kind = CK_NoOp;
3019        return;
3020      }
3021  
3022      // GCC's cast to union extension.
3023      if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) {
3024        RecordDecl *RD = DestRecordTy->getDecl();
3025        if (CastExpr::getTargetFieldForToUnionCast(RD, SrcType)) {
3026          Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union)
3027            << SrcExpr.get()->getSourceRange();
3028          Kind = CK_ToUnion;
3029          return;
3030        } else {
3031          Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type)
3032            << SrcType << SrcExpr.get()->getSourceRange();
3033          SrcExpr = ExprError();
3034          return;
3035        }
3036      }
3037  
3038      // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type.
3039      if (Self.getLangOpts().OpenCL && DestType->isEventT()) {
3040        Expr::EvalResult Result;
3041        if (SrcExpr.get()->EvaluateAsInt(Result, Self.Context)) {
3042          llvm::APSInt CastInt = Result.Val.getInt();
3043          if (0 == CastInt) {
3044            Kind = CK_ZeroToOCLOpaqueType;
3045            return;
3046          }
3047          Self.Diag(OpRange.getBegin(),
3048                    diag::err_opencl_cast_non_zero_to_event_t)
3049                    << toString(CastInt, 10) << SrcExpr.get()->getSourceRange();
3050          SrcExpr = ExprError();
3051          return;
3052        }
3053      }
3054  
3055      // Reject any other conversions to non-scalar types.
3056      Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar)
3057        << DestType << SrcExpr.get()->getSourceRange();
3058      SrcExpr = ExprError();
3059      return;
3060    }
3061  
3062    // The type we're casting to is known to be a scalar, a vector, or a matrix.
3063  
3064    // Require the operand to be a scalar, a vector, or a matrix.
3065    if (!SrcType->isScalarType() && !SrcType->isVectorType() &&
3066        !SrcType->isMatrixType()) {
3067      Self.Diag(SrcExpr.get()->getExprLoc(),
3068                diag::err_typecheck_expect_scalar_operand)
3069        << SrcType << SrcExpr.get()->getSourceRange();
3070      SrcExpr = ExprError();
3071      return;
3072    }
3073  
3074    // C23 6.5.4p4:
3075    //   The type nullptr_t shall not be converted to any type other than void,
3076    //   bool, or a pointer type. No type other than nullptr_t shall be converted
3077    //   to nullptr_t.
3078    if (SrcType->isNullPtrType()) {
3079      // FIXME: 6.3.2.4p2 says that nullptr_t can be converted to itself, but
3080      // 6.5.4p4 is a constraint check and nullptr_t is not void, bool, or a
3081      // pointer type. We're not going to diagnose that as a constraint violation.
3082      if (!DestType->isVoidType() && !DestType->isBooleanType() &&
3083          !DestType->isPointerType() && !DestType->isNullPtrType()) {
3084        Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_nullptr_cast)
3085            << /*nullptr to type*/ 0 << DestType;
3086        SrcExpr = ExprError();
3087        return;
3088      }
3089      if (!DestType->isNullPtrType()) {
3090        // Implicitly cast from the null pointer type to the type of the
3091        // destination.
3092        CastKind CK = DestType->isPointerType() ? CK_NullToPointer : CK_BitCast;
3093        SrcExpr = ImplicitCastExpr::Create(Self.Context, DestType, CK,
3094                                           SrcExpr.get(), nullptr, VK_PRValue,
3095                                           Self.CurFPFeatureOverrides());
3096      }
3097    }
3098    if (DestType->isNullPtrType() && !SrcType->isNullPtrType()) {
3099      Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_nullptr_cast)
3100          << /*type to nullptr*/ 1 << SrcType;
3101      SrcExpr = ExprError();
3102      return;
3103    }
3104  
3105    if (DestType->isExtVectorType()) {
3106      SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind);
3107      return;
3108    }
3109  
3110    if (DestType->getAs<MatrixType>() || SrcType->getAs<MatrixType>()) {
3111      if (Self.CheckMatrixCast(OpRange, DestType, SrcType, Kind))
3112        SrcExpr = ExprError();
3113      return;
3114    }
3115  
3116    if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) {
3117      if (Self.CheckAltivecInitFromScalar(OpRange, DestType, SrcType)) {
3118        SrcExpr = ExprError();
3119        return;
3120      }
3121      if (Self.ShouldSplatAltivecScalarInCast(DestVecTy) &&
3122          (SrcType->isIntegerType() || SrcType->isFloatingType())) {
3123        Kind = CK_VectorSplat;
3124        SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get());
3125      } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) {
3126        SrcExpr = ExprError();
3127      }
3128      return;
3129    }
3130  
3131    if (SrcType->isVectorType()) {
3132      if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind))
3133        SrcExpr = ExprError();
3134      return;
3135    }
3136  
3137    // The source and target types are both scalars, i.e.
3138    //   - arithmetic types (fundamental, enum, and complex)
3139    //   - all kinds of pointers
3140    // Note that member pointers were filtered out with C++, above.
3141  
3142    if (isa<ObjCSelectorExpr>(SrcExpr.get())) {
3143      Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr);
3144      SrcExpr = ExprError();
3145      return;
3146    }
3147  
3148    // If either type is a pointer, the other type has to be either an
3149    // integer or a pointer.
3150    if (!DestType->isArithmeticType()) {
3151      if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) {
3152        Self.Diag(SrcExpr.get()->getExprLoc(),
3153                  diag::err_cast_pointer_from_non_pointer_int)
3154          << SrcType << SrcExpr.get()->getSourceRange();
3155        SrcExpr = ExprError();
3156        return;
3157      }
3158      checkIntToPointerCast(/* CStyle */ true, OpRange, SrcExpr.get(), DestType,
3159                            Self);
3160    } else if (!SrcType->isArithmeticType()) {
3161      if (!DestType->isIntegralType(Self.Context) &&
3162          DestType->isArithmeticType()) {
3163        Self.Diag(SrcExpr.get()->getBeginLoc(),
3164                  diag::err_cast_pointer_to_non_pointer_int)
3165            << DestType << SrcExpr.get()->getSourceRange();
3166        SrcExpr = ExprError();
3167        return;
3168      }
3169  
3170      if ((Self.Context.getTypeSize(SrcType) >
3171           Self.Context.getTypeSize(DestType)) &&
3172          !DestType->isBooleanType()) {
3173        // C 6.3.2.3p6: Any pointer type may be converted to an integer type.
3174        // Except as previously specified, the result is implementation-defined.
3175        // If the result cannot be represented in the integer type, the behavior
3176        // is undefined. The result need not be in the range of values of any
3177        // integer type.
3178        unsigned Diag;
3179        if (SrcType->isVoidPointerType())
3180          Diag = DestType->isEnumeralType() ? diag::warn_void_pointer_to_enum_cast
3181                                            : diag::warn_void_pointer_to_int_cast;
3182        else if (DestType->isEnumeralType())
3183          Diag = diag::warn_pointer_to_enum_cast;
3184        else
3185          Diag = diag::warn_pointer_to_int_cast;
3186        Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
3187      }
3188    }
3189  
3190    if (Self.getLangOpts().OpenCL && !Self.getOpenCLOptions().isAvailableOption(
3191                                         "cl_khr_fp16", Self.getLangOpts())) {
3192      if (DestType->isHalfType()) {
3193        Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_opencl_cast_to_half)
3194            << DestType << SrcExpr.get()->getSourceRange();
3195        SrcExpr = ExprError();
3196        return;
3197      }
3198    }
3199  
3200    // ARC imposes extra restrictions on casts.
3201    if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) {
3202      checkObjCConversion(CheckedConversionKind::CStyleCast);
3203      if (SrcExpr.isInvalid())
3204        return;
3205  
3206      const PointerType *CastPtr = DestType->getAs<PointerType>();
3207      if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) {
3208        if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) {
3209          Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers();
3210          Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers();
3211          if (CastPtr->getPointeeType()->isObjCLifetimeType() &&
3212              ExprPtr->getPointeeType()->isObjCLifetimeType() &&
3213              !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) {
3214            Self.Diag(SrcExpr.get()->getBeginLoc(),
3215                      diag::err_typecheck_incompatible_ownership)
3216                << SrcType << DestType << Sema::AA_Casting
3217                << SrcExpr.get()->getSourceRange();
3218            return;
3219          }
3220        }
3221      } else if (!Self.ObjC().CheckObjCARCUnavailableWeakConversion(DestType,
3222                                                                    SrcType)) {
3223        Self.Diag(SrcExpr.get()->getBeginLoc(),
3224                  diag::err_arc_convesion_of_weak_unavailable)
3225            << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange();
3226        SrcExpr = ExprError();
3227        return;
3228      }
3229    }
3230  
3231    if (unsigned DiagID = checkCastFunctionType(Self, SrcExpr, DestType))
3232      Self.Diag(OpRange.getBegin(), DiagID) << SrcType << DestType << OpRange;
3233  
3234    if (isa<PointerType>(SrcType) && isa<PointerType>(DestType)) {
3235      QualType SrcTy = cast<PointerType>(SrcType)->getPointeeType();
3236      QualType DestTy = cast<PointerType>(DestType)->getPointeeType();
3237  
3238      const RecordDecl *SrcRD = SrcTy->getAsRecordDecl();
3239      const RecordDecl *DestRD = DestTy->getAsRecordDecl();
3240  
3241      if (SrcRD && DestRD && SrcRD->hasAttr<RandomizeLayoutAttr>() &&
3242          SrcRD != DestRD) {
3243        // The struct we are casting the pointer from was randomized.
3244        Self.Diag(OpRange.getBegin(), diag::err_cast_from_randomized_struct)
3245            << SrcType << DestType;
3246        SrcExpr = ExprError();
3247        return;
3248      }
3249    }
3250  
3251    DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
3252    DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange);
3253    DiagnoseBadFunctionCast(Self, SrcExpr, DestType);
3254    Kind = Self.PrepareScalarCast(SrcExpr, DestType);
3255    if (SrcExpr.isInvalid())
3256      return;
3257  
3258    if (Kind == CK_BitCast)
3259      checkCastAlign();
3260  }
3261  
3262  void CastOperation::CheckBuiltinBitCast() {
3263    QualType SrcType = SrcExpr.get()->getType();
3264  
3265    if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
3266                                 diag::err_typecheck_cast_to_incomplete) ||
3267        Self.RequireCompleteType(OpRange.getBegin(), SrcType,
3268                                 diag::err_incomplete_type)) {
3269      SrcExpr = ExprError();
3270      return;
3271    }
3272  
3273    if (SrcExpr.get()->isPRValue())
3274      SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(),
3275                                                    /*IsLValueReference=*/false);
3276  
3277    CharUnits DestSize = Self.Context.getTypeSizeInChars(DestType);
3278    CharUnits SourceSize = Self.Context.getTypeSizeInChars(SrcType);
3279    if (DestSize != SourceSize) {
3280      Self.Diag(OpRange.getBegin(), diag::err_bit_cast_type_size_mismatch)
3281          << (int)SourceSize.getQuantity() << (int)DestSize.getQuantity();
3282      SrcExpr = ExprError();
3283      return;
3284    }
3285  
3286    if (!DestType.isTriviallyCopyableType(Self.Context)) {
3287      Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable)
3288          << 1;
3289      SrcExpr = ExprError();
3290      return;
3291    }
3292  
3293    if (!SrcType.isTriviallyCopyableType(Self.Context)) {
3294      Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable)
3295          << 0;
3296      SrcExpr = ExprError();
3297      return;
3298    }
3299  
3300    Kind = CK_LValueToRValueBitCast;
3301  }
3302  
3303  /// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either
3304  /// const, volatile or both.
3305  static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
3306                               QualType DestType) {
3307    if (SrcExpr.isInvalid())
3308      return;
3309  
3310    QualType SrcType = SrcExpr.get()->getType();
3311    if (!((SrcType->isAnyPointerType() && DestType->isAnyPointerType()) ||
3312          DestType->isLValueReferenceType()))
3313      return;
3314  
3315    QualType TheOffendingSrcType, TheOffendingDestType;
3316    Qualifiers CastAwayQualifiers;
3317    if (CastsAwayConstness(Self, SrcType, DestType, true, false,
3318                           &TheOffendingSrcType, &TheOffendingDestType,
3319                           &CastAwayQualifiers) !=
3320        CastAwayConstnessKind::CACK_Similar)
3321      return;
3322  
3323    // FIXME: 'restrict' is not properly handled here.
3324    int qualifiers = -1;
3325    if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) {
3326      qualifiers = 0;
3327    } else if (CastAwayQualifiers.hasConst()) {
3328      qualifiers = 1;
3329    } else if (CastAwayQualifiers.hasVolatile()) {
3330      qualifiers = 2;
3331    }
3332    // This is a variant of int **x; const int **y = (const int **)x;
3333    if (qualifiers == -1)
3334      Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual2)
3335          << SrcType << DestType;
3336    else
3337      Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual)
3338          << TheOffendingSrcType << TheOffendingDestType << qualifiers;
3339  }
3340  
3341  ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
3342                                       TypeSourceInfo *CastTypeInfo,
3343                                       SourceLocation RPLoc,
3344                                       Expr *CastExpr) {
3345    CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
3346    Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
3347    Op.OpRange = SourceRange(LPLoc, CastExpr->getEndLoc());
3348  
3349    if (getLangOpts().CPlusPlus) {
3350      Op.CheckCXXCStyleCast(/*FunctionalCast=*/ false,
3351                            isa<InitListExpr>(CastExpr));
3352    } else {
3353      Op.CheckCStyleCast();
3354    }
3355  
3356    if (Op.SrcExpr.isInvalid())
3357      return ExprError();
3358  
3359    // -Wcast-qual
3360    DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType);
3361  
3362    return Op.complete(CStyleCastExpr::Create(
3363        Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
3364        &Op.BasePath, CurFPFeatureOverrides(), CastTypeInfo, LPLoc, RPLoc));
3365  }
3366  
3367  ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo,
3368                                              QualType Type,
3369                                              SourceLocation LPLoc,
3370                                              Expr *CastExpr,
3371                                              SourceLocation RPLoc) {
3372    assert(LPLoc.isValid() && "List-initialization shouldn't get here.");
3373    CastOperation Op(*this, Type, CastExpr);
3374    Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
3375    Op.OpRange = SourceRange(Op.DestRange.getBegin(), RPLoc);
3376  
3377    Op.CheckCXXCStyleCast(/*FunctionalCast=*/true, /*ListInit=*/false);
3378    if (Op.SrcExpr.isInvalid())
3379      return ExprError();
3380  
3381    auto *SubExpr = Op.SrcExpr.get();
3382    if (auto *BindExpr = dyn_cast<CXXBindTemporaryExpr>(SubExpr))
3383      SubExpr = BindExpr->getSubExpr();
3384    if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr))
3385      ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc));
3386  
3387    // -Wcast-qual
3388    DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType);
3389  
3390    return Op.complete(CXXFunctionalCastExpr::Create(
3391        Context, Op.ResultType, Op.ValueKind, CastTypeInfo, Op.Kind,
3392        Op.SrcExpr.get(), &Op.BasePath, CurFPFeatureOverrides(), LPLoc, RPLoc));
3393  }
3394