1 //===-- HeaderIncludeGen.cpp - Generate Header Includes -------------------===// 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 #include "clang/Frontend/DependencyOutputOptions.h" 10 #include "clang/Frontend/Utils.h" 11 #include "clang/Basic/SourceManager.h" 12 #include "clang/Frontend/FrontendDiagnostic.h" 13 #include "clang/Lex/Preprocessor.h" 14 #include "llvm/ADT/SmallString.h" 15 #include "llvm/Support/raw_ostream.h" 16 using namespace clang; 17 18 namespace { 19 class HeaderIncludesCallback : public PPCallbacks { 20 SourceManager &SM; 21 raw_ostream *OutputFile; 22 const DependencyOutputOptions &DepOpts; 23 unsigned CurrentIncludeDepth; 24 bool HasProcessedPredefines; 25 bool OwnsOutputFile; 26 bool ShowAllHeaders; 27 bool ShowDepth; 28 bool MSStyle; 29 30 public: 31 HeaderIncludesCallback(const Preprocessor *PP, bool ShowAllHeaders_, 32 raw_ostream *OutputFile_, 33 const DependencyOutputOptions &DepOpts, 34 bool OwnsOutputFile_, bool ShowDepth_, bool MSStyle_) 35 : SM(PP->getSourceManager()), OutputFile(OutputFile_), DepOpts(DepOpts), 36 CurrentIncludeDepth(0), HasProcessedPredefines(false), 37 OwnsOutputFile(OwnsOutputFile_), ShowAllHeaders(ShowAllHeaders_), 38 ShowDepth(ShowDepth_), MSStyle(MSStyle_) {} 39 40 ~HeaderIncludesCallback() override { 41 if (OwnsOutputFile) 42 delete OutputFile; 43 } 44 45 void FileChanged(SourceLocation Loc, FileChangeReason Reason, 46 SrcMgr::CharacteristicKind FileType, 47 FileID PrevFID) override; 48 }; 49 } 50 51 static void PrintHeaderInfo(raw_ostream *OutputFile, StringRef Filename, 52 bool ShowDepth, unsigned CurrentIncludeDepth, 53 bool MSStyle) { 54 // Write to a temporary string to avoid unnecessary flushing on errs(). 55 SmallString<512> Pathname(Filename); 56 if (!MSStyle) 57 Lexer::Stringify(Pathname); 58 59 SmallString<256> Msg; 60 if (MSStyle) 61 Msg += "Note: including file:"; 62 63 if (ShowDepth) { 64 // The main source file is at depth 1, so skip one dot. 65 for (unsigned i = 1; i != CurrentIncludeDepth; ++i) 66 Msg += MSStyle ? ' ' : '.'; 67 68 if (!MSStyle) 69 Msg += ' '; 70 } 71 Msg += Pathname; 72 Msg += '\n'; 73 74 *OutputFile << Msg; 75 OutputFile->flush(); 76 } 77 78 void clang::AttachHeaderIncludeGen(Preprocessor &PP, 79 const DependencyOutputOptions &DepOpts, 80 bool ShowAllHeaders, StringRef OutputPath, 81 bool ShowDepth, bool MSStyle) { 82 raw_ostream *OutputFile = &llvm::errs(); 83 bool OwnsOutputFile = false; 84 85 // Choose output stream, when printing in cl.exe /showIncludes style. 86 if (MSStyle) { 87 switch (DepOpts.ShowIncludesDest) { 88 default: 89 llvm_unreachable("Invalid destination for /showIncludes output!"); 90 case ShowIncludesDestination::Stderr: 91 OutputFile = &llvm::errs(); 92 break; 93 case ShowIncludesDestination::Stdout: 94 OutputFile = &llvm::outs(); 95 break; 96 } 97 } 98 99 // Open the output file, if used. 100 if (!OutputPath.empty()) { 101 std::error_code EC; 102 llvm::raw_fd_ostream *OS = new llvm::raw_fd_ostream( 103 OutputPath.str(), EC, 104 llvm::sys::fs::OF_Append | llvm::sys::fs::OF_Text); 105 if (EC) { 106 PP.getDiagnostics().Report(clang::diag::warn_fe_cc_print_header_failure) 107 << EC.message(); 108 delete OS; 109 } else { 110 OS->SetUnbuffered(); 111 OutputFile = OS; 112 OwnsOutputFile = true; 113 } 114 } 115 116 // Print header info for extra headers, pretending they were discovered by 117 // the regular preprocessor. The primary use case is to support proper 118 // generation of Make / Ninja file dependencies for implicit includes, such 119 // as sanitizer blacklists. It's only important for cl.exe compatibility, 120 // the GNU way to generate rules is -M / -MM / -MD / -MMD. 121 for (const auto &Header : DepOpts.ExtraDeps) 122 PrintHeaderInfo(OutputFile, Header, ShowDepth, 2, MSStyle); 123 PP.addPPCallbacks(std::make_unique<HeaderIncludesCallback>( 124 &PP, ShowAllHeaders, OutputFile, DepOpts, OwnsOutputFile, ShowDepth, 125 MSStyle)); 126 } 127 128 void HeaderIncludesCallback::FileChanged(SourceLocation Loc, 129 FileChangeReason Reason, 130 SrcMgr::CharacteristicKind NewFileType, 131 FileID PrevFID) { 132 // Unless we are exiting a #include, make sure to skip ahead to the line the 133 // #include directive was at. 134 PresumedLoc UserLoc = SM.getPresumedLoc(Loc); 135 if (UserLoc.isInvalid()) 136 return; 137 138 // Adjust the current include depth. 139 if (Reason == PPCallbacks::EnterFile) { 140 ++CurrentIncludeDepth; 141 } else if (Reason == PPCallbacks::ExitFile) { 142 if (CurrentIncludeDepth) 143 --CurrentIncludeDepth; 144 145 // We track when we are done with the predefines by watching for the first 146 // place where we drop back to a nesting depth of 1. 147 if (CurrentIncludeDepth == 1 && !HasProcessedPredefines) { 148 if (!DepOpts.ShowIncludesPretendHeader.empty()) { 149 PrintHeaderInfo(OutputFile, DepOpts.ShowIncludesPretendHeader, 150 ShowDepth, 2, MSStyle); 151 } 152 HasProcessedPredefines = true; 153 } 154 155 return; 156 } else 157 return; 158 159 // Show the header if we are (a) past the predefines, or (b) showing all 160 // headers and in the predefines at a depth past the initial file and command 161 // line buffers. 162 bool ShowHeader = (HasProcessedPredefines || 163 (ShowAllHeaders && CurrentIncludeDepth > 2)); 164 unsigned IncludeDepth = CurrentIncludeDepth; 165 if (!HasProcessedPredefines) 166 --IncludeDepth; // Ignore indent from <built-in>. 167 else if (!DepOpts.ShowIncludesPretendHeader.empty()) 168 ++IncludeDepth; // Pretend inclusion by ShowIncludesPretendHeader. 169 170 // Dump the header include information we are past the predefines buffer or 171 // are showing all headers and this isn't the magic implicit <command line> 172 // header. 173 // FIXME: Identify headers in a more robust way than comparing their name to 174 // "<command line>" and "<built-in>" in a bunch of places. 175 if (ShowHeader && Reason == PPCallbacks::EnterFile && 176 UserLoc.getFilename() != StringRef("<command line>")) { 177 PrintHeaderInfo(OutputFile, UserLoc.getFilename(), ShowDepth, IncludeDepth, 178 MSStyle); 179 } 180 } 181