1 # $NetBSD: cond-short.mk,v 1.12 2020/11/15 14:58:14 rillig Exp $
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'.
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?
15 .if 0 && ${echo "unexpected and" 1>&2 :L:sh}
18 .if 1 && ${echo "expected and" 1>&2 :L:sh}
21 .if 0 && exists(nonexistent${echo "unexpected and exists" 1>&2 :L:sh})
24 .if 1 && exists(nonexistent${echo "expected and exists" 1>&2 :L:sh})
27 .if 0 && empty(${echo "unexpected and empty" 1>&2 :L:sh})
30 .if 1 && empty(${echo "expected and empty" 1>&2 :L:sh})
33 # "VAR U11" is not evaluated; it was evaluated before 2020-07-02.
34 # The whole !empty condition is only parsed and then discarded.
35 VAR= ${VAR${:U11${echo "unexpected VAR U11" 1>&2 :L:sh}}}
36 VAR13= ${VAR${:U12${echo "unexpected VAR13" 1>&2 :L:sh}}}
37 .if 0 && !empty(VAR${:U13${echo "unexpected U13 condition" 1>&2 :L:sh}})
40 VAR= ${VAR${:U21${echo "unexpected VAR U21" 1>&2 :L:sh}}}
41 VAR23= ${VAR${:U22${echo "expected VAR23" 1>&2 :L:sh}}}
42 .if 1 && !empty(VAR${:U23${echo "expected U23 condition" 1>&2 :L:sh}})
44 VAR= # empty again, for the following tests
46 # The :M modifier is only parsed, not evaluated.
47 # Before 2020-07-02, it was wrongly evaluated.
48 .if 0 && !empty(VAR:M${:U${echo "unexpected M pattern" 1>&2 :L:sh}})
51 .if 1 && !empty(VAR:M${:U${echo "expected M pattern" 1>&2 :L:sh}})
54 .if 0 && !empty(VAR:S,from,${:U${echo "unexpected S modifier" 1>&2 :L:sh}},)
57 .if 0 && !empty(VAR:C,from,${:U${echo "unexpected C modifier" 1>&2 :L:sh}},)
60 .if 0 && !empty("" == "" :? ${:U${echo "unexpected ? modifier" 1>&2 :L:sh}} :)
63 .if 0 && !empty(VAR:old=${:U${echo "unexpected = modifier" 1>&2 :L:sh}})
66 .if 0 && !empty(1 2 3:L:@var@${:U${echo "unexpected @ modifier" 1>&2 :L:sh}}@)
69 .if 0 && !empty(:U${:!echo "unexpected exclam modifier" 1>&2 !})
72 # Irrelevant assignment modifiers are skipped as well.
73 .if 0 && ${1 2 3:L:@i@${FIRST::?=$i}@}
75 .if 0 && ${1 2 3:L:@i@${LAST::=$i}@}
77 .if 0 && ${1 2 3:L:@i@${APPENDED::+=$i}@}
79 .if 0 && ${echo.1 echo.2 echo.3:L:@i@${RAN::!=${i:C,.*,&; & 1>\&2,:S,., ,g}}@}
81 .if defined(FIRST) || defined(LAST) || defined(APPENDED) || defined(RAN)
82 . warning first=${FIRST} last=${LAST} appended=${APPENDED} ran=${RAN}
87 .if 1 || ${echo "unexpected or" 1>&2 :L:sh}
90 .if 0 || ${echo "expected or" 1>&2 :L:sh}
93 .if 1 || exists(nonexistent${echo "unexpected or exists" 1>&2 :L:sh})
96 .if 0 || exists(nonexistent${echo "expected or exists" 1>&2 :L:sh})
99 .if 1 || empty(${echo "unexpected or empty" 1>&2 :L:sh})
102 .if 0 || empty(${echo "expected or empty" 1>&2 :L:sh})
105 # Unreachable nested conditions are skipped completely as well.
108 . if ${echo "unexpected nested and" 1>&2 :L:sh}
113 .elif ${echo "unexpected nested or" 1>&2 :L:sh}
116 # make sure these do not cause complaint
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'.
126 .if defined(V42) && ${V42} > 0
131 x!= echo 'defined(V42) && ${V42} > 0: $x' >&2; echo
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} < ${V42} )
141 x!= echo 'defined(V66) && ( "${iV2}" < ${V42} ): $x' >&2; echo
143 # next two thow String comparison operator with cond.c 1.78
144 # indirect iV1 would expand to 42
145 .if 1 || ${iV1} < ${V42}
150 x!= echo '1 || ${iV1} < ${V42}: $x' >&2; echo
152 .if 1 || ${iV2:U2} < ${V42}
157 x!= echo '1 || ${iV2:U2} < ${V42}: $x' >&2; echo
159 # the same expressions are fine when the lhs is expanded
160 # ${iV1} expands to 42
161 .if 0 || ${iV1} <= ${V42}
166 x!= echo '0 || ${iV1} <= ${V42}: $x' >&2; echo
168 # ${iV2:U2} expands to 2
169 .if 0 || ${iV2:U2} < ${V42}
174 x!= echo '0 || ${iV2:U2} < ${V42}: $x' >&2; echo
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"
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