1# $NetBSD: cond-short.mk,v 1.12 2020/11/15 14:58:14 rillig Exp $ 2# 3# Demonstrates that in conditions, the right-hand side of an && or || 4# is only evaluated if it can actually influence the result. 5# This is called 'short-circuit evaluation' and is the usual evaluation 6# mode in most programming languages. A notable exception is Ada, which 7# distinguishes between the operators 'And', 'And Then', 'Or', 'Or Else'. 8# 9# Between 2015-10-11 and 2020-06-28, the right-hand side of an && or || 10# operator was always evaluated, which was wrong. 11# TODO: Had the evaluation been correct at some time before 2015-11-12? 12 13# The && operator. 14 15.if 0 && ${echo "unexpected and" 1>&2 :L:sh} 16.endif 17 18.if 1 && ${echo "expected and" 1>&2 :L:sh} 19.endif 20 21.if 0 && exists(nonexistent${echo "unexpected and exists" 1>&2 :L:sh}) 22.endif 23 24.if 1 && exists(nonexistent${echo "expected and exists" 1>&2 :L:sh}) 25.endif 26 27.if 0 && empty(${echo "unexpected and empty" 1>&2 :L:sh}) 28.endif 29 30.if 1 && empty(${echo "expected and empty" 1>&2 :L:sh}) 31.endif 32 33# "VAR U11" is not evaluated; it was evaluated before 2020-07-02. 34# The whole !empty condition is only parsed and then discarded. 35VAR= ${VAR${:U11${echo "unexpected VAR U11" 1>&2 :L:sh}}} 36VAR13= ${VAR${:U12${echo "unexpected VAR13" 1>&2 :L:sh}}} 37.if 0 && !empty(VAR${:U13${echo "unexpected U13 condition" 1>&2 :L:sh}}) 38.endif 39 40VAR= ${VAR${:U21${echo "unexpected VAR U21" 1>&2 :L:sh}}} 41VAR23= ${VAR${:U22${echo "expected VAR23" 1>&2 :L:sh}}} 42.if 1 && !empty(VAR${:U23${echo "expected U23 condition" 1>&2 :L:sh}}) 43.endif 44VAR= # empty again, for the following tests 45 46# The :M modifier is only parsed, not evaluated. 47# Before 2020-07-02, it was wrongly evaluated. 48.if 0 && !empty(VAR:M${:U${echo "unexpected M pattern" 1>&2 :L:sh}}) 49.endif 50 51.if 1 && !empty(VAR:M${:U${echo "expected M pattern" 1>&2 :L:sh}}) 52.endif 53 54.if 0 && !empty(VAR:S,from,${:U${echo "unexpected S modifier" 1>&2 :L:sh}},) 55.endif 56 57.if 0 && !empty(VAR:C,from,${:U${echo "unexpected C modifier" 1>&2 :L:sh}},) 58.endif 59 60.if 0 && !empty("" == "" :? ${:U${echo "unexpected ? modifier" 1>&2 :L:sh}} :) 61.endif 62 63.if 0 && !empty(VAR:old=${:U${echo "unexpected = modifier" 1>&2 :L:sh}}) 64.endif 65 66.if 0 && !empty(1 2 3:L:@var@${:U${echo "unexpected @ modifier" 1>&2 :L:sh}}@) 67.endif 68 69.if 0 && !empty(:U${:!echo "unexpected exclam modifier" 1>&2 !}) 70.endif 71 72# Irrelevant assignment modifiers are skipped as well. 73.if 0 && ${1 2 3:L:@i@${FIRST::?=$i}@} 74.endif 75.if 0 && ${1 2 3:L:@i@${LAST::=$i}@} 76.endif 77.if 0 && ${1 2 3:L:@i@${APPENDED::+=$i}@} 78.endif 79.if 0 && ${echo.1 echo.2 echo.3:L:@i@${RAN::!=${i:C,.*,&; & 1>\&2,:S,., ,g}}@} 80.endif 81.if defined(FIRST) || defined(LAST) || defined(APPENDED) || defined(RAN) 82. warning first=${FIRST} last=${LAST} appended=${APPENDED} ran=${RAN} 83.endif 84 85# The || operator. 86 87.if 1 || ${echo "unexpected or" 1>&2 :L:sh} 88.endif 89 90.if 0 || ${echo "expected or" 1>&2 :L:sh} 91.endif 92 93.if 1 || exists(nonexistent${echo "unexpected or exists" 1>&2 :L:sh}) 94.endif 95 96.if 0 || exists(nonexistent${echo "expected or exists" 1>&2 :L:sh}) 97.endif 98 99.if 1 || empty(${echo "unexpected or empty" 1>&2 :L:sh}) 100.endif 101 102.if 0 || empty(${echo "expected or empty" 1>&2 :L:sh}) 103.endif 104 105# Unreachable nested conditions are skipped completely as well. 106 107.if 0 108. if ${echo "unexpected nested and" 1>&2 :L:sh} 109. endif 110.endif 111 112.if 1 113.elif ${echo "unexpected nested or" 1>&2 :L:sh} 114.endif 115 116# make sure these do not cause complaint 117#.MAKEFLAGS: -dc 118 119# TODO: Rewrite this whole section and check all the conditions and variables. 120# Several of the assumptions are probably wrong here. 121# TODO: replace 'x=' with '.info' or '.error'. 122V42= 42 123iV1= ${V42} 124iV2= ${V66} 125 126.if defined(V42) && ${V42} > 0 127x= Ok 128.else 129x= Fail 130.endif 131x!= echo 'defined(V42) && ${V42} > 0: $x' >&2; echo 132 133# this one throws both String comparison operator and 134# Malformed conditional with cond.c 1.78 135# indirect iV2 would expand to "" and treated as 0 136.if defined(V66) && ( ${iV2} < ${V42} ) 137x= Fail 138.else 139x= Ok 140.endif 141x!= echo 'defined(V66) && ( "${iV2}" < ${V42} ): $x' >&2; echo 142 143# next two thow String comparison operator with cond.c 1.78 144# indirect iV1 would expand to 42 145.if 1 || ${iV1} < ${V42} 146x= Ok 147.else 148x= Fail 149.endif 150x!= echo '1 || ${iV1} < ${V42}: $x' >&2; echo 151 152.if 1 || ${iV2:U2} < ${V42} 153x= Ok 154.else 155x= Fail 156.endif 157x!= echo '1 || ${iV2:U2} < ${V42}: $x' >&2; echo 158 159# the same expressions are fine when the lhs is expanded 160# ${iV1} expands to 42 161.if 0 || ${iV1} <= ${V42} 162x= Ok 163.else 164x= Fail 165.endif 166x!= echo '0 || ${iV1} <= ${V42}: $x' >&2; echo 167 168# ${iV2:U2} expands to 2 169.if 0 || ${iV2:U2} < ${V42} 170x= Ok 171.else 172x= Fail 173.endif 174x!= echo '0 || ${iV2:U2} < ${V42}: $x' >&2; echo 175 176# TODO: Has this always worked? There may have been a time, maybe around 177# 2000, when make would complain about the "Malformed conditional" because 178# UNDEF is not defined. 179.if defined(UNDEF) && ${UNDEF} != "undefined" 180. error 181.endif 182 183# TODO: Test each modifier to make sure it is skipped when it is irrelevant 184# for the result. Since this test is already quite long, do that in another 185# test. 186 187all: 188 @:;: 189