[src/trunk]: src/usr.bin/make/unit-tests tests/make: expand on the history of...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c0869be04db2
branches:  trunk
changeset: 1023447:c0869be04db2
user:      rillig <rillig%NetBSD.org@localhost>
date:      Tue Sep 07 20:41:58 2021 +0000

description:
tests/make: expand on the history of unnecessary evaluation

diffstat:

 usr.bin/make/unit-tests/cond-short.mk      |  17 +++++++++++++++--
 usr.bin/make/unit-tests/var-eval-short.exp |  12 ++++++------
 usr.bin/make/unit-tests/var-eval-short.mk  |  12 +++++++-----
 3 files changed, 28 insertions(+), 13 deletions(-)

diffs (91 lines):

diff -r 14f148156703 -r c0869be04db2 usr.bin/make/unit-tests/cond-short.mk
--- a/usr.bin/make/unit-tests/cond-short.mk     Tue Sep 07 18:02:46 2021 +0000
+++ b/usr.bin/make/unit-tests/cond-short.mk     Tue Sep 07 20:41:58 2021 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: cond-short.mk,v 1.16 2021/03/14 11:49:37 rillig Exp $
+# $NetBSD: cond-short.mk,v 1.17 2021/09/07 20:41:58 rillig Exp $
 #
 # Demonstrates that in conditions, the right-hand side of an && or ||
 # is only evaluated if it can actually influence the result.
@@ -12,7 +12,20 @@
 # possible to skip evaluation of irrelevant variable expressions and only
 # parse them.  They were still evaluated though, the only difference to
 # relevant variable expressions was that in the irrelevant variable
-# expressions, undefined variables were allowed.
+# expressions, undefined variables were allowed.  This allowed for conditions
+# like 'defined(VAR) && ${VAR:S,from,to,} != ""', which no longer produced an
+# error message 'Malformed conditional', but it still evaluated the
+# expression, even though the expression was irrelevant.
+#
+# Since the initial commit on 1993-03-21, the manual page has been saying that
+# make 'will only evaluate a conditional as far as is necessary to determine',
+# but that was wrong.  The code in cond.c 1.1 from 1993-03-21 looks good since
+# it calls Var_Parse(condExpr, VAR_CMD, doEval,&varSpecLen,&doFree), but the
+# definition of Var_Parse does not call the third parameter 'doEval', as would
+# be expected, but instead 'err', accompanied by the comment 'TRUE if
+# undefined variables are an error'.  This subtle difference between 'do not
+# evaluate at all' and 'allow undefined variables' led to the unexpected
+# evaluation.
 #
 # See also:
 #      var-eval-short.mk, for short-circuited variable modifiers
diff -r 14f148156703 -r c0869be04db2 usr.bin/make/unit-tests/var-eval-short.exp
--- a/usr.bin/make/unit-tests/var-eval-short.exp        Tue Sep 07 18:02:46 2021 +0000
+++ b/usr.bin/make/unit-tests/var-eval-short.exp        Tue Sep 07 20:41:58 2021 +0000
@@ -1,16 +1,16 @@
 make: "var-eval-short.mk" line 41: In the :@ modifier of "", the variable name "${FAIL}" must not contain a dollar.
 make: "var-eval-short.mk" line 41: Malformed conditional (0 && ${:Uword:@${FAIL}@expr@})
-make: "var-eval-short.mk" line 79: Invalid time value: ${FAIL}}
-make: "var-eval-short.mk" line 79: Malformed conditional (0 && ${:Uword:gmtime=${FAIL}})
-make: "var-eval-short.mk" line 93: Invalid time value: ${FAIL}}
-make: "var-eval-short.mk" line 93: Malformed conditional (0 && ${:Uword:localtime=${FAIL}})
+make: "var-eval-short.mk" line 81: Invalid time value: ${FAIL}}
+make: "var-eval-short.mk" line 81: Malformed conditional (0 && ${:Uword:gmtime=${FAIL}})
+make: "var-eval-short.mk" line 95: Invalid time value: ${FAIL}}
+make: "var-eval-short.mk" line 95: Malformed conditional (0 && ${:Uword:localtime=${FAIL}})
 CondParser_Eval: 0 && ${0:?${FAIL}then:${FAIL}else}
 Var_Parse: ${0:?${FAIL}then:${FAIL}else} (parse-only)
 Parsing modifier ${0:?...}
 Modifier part: "${FAIL}then"
 Modifier part: "${FAIL}else"
 Result of ${0:?${FAIL}then:${FAIL}else} is "" (parse-only, defined)
-ParseReadLine (158): 'DEFINED= defined'
+ParseReadLine (160): 'DEFINED= defined'
 Global: DEFINED = defined
 CondParser_Eval: 0 && ${DEFINED:L:?${FAIL}then:${FAIL}else}
 Var_Parse: ${DEFINED:L:?${FAIL}then:${FAIL}else} (parse-only)
@@ -20,7 +20,7 @@
 Modifier part: "${FAIL}then"
 Modifier part: "${FAIL}else"
 Result of ${DEFINED:?${FAIL}then:${FAIL}else} is "defined" (parse-only, regular)
-ParseReadLine (161): '.MAKEFLAGS: -d0'
+ParseReadLine (163): '.MAKEFLAGS: -d0'
 ParseDependency(.MAKEFLAGS: -d0)
 Global: .MAKEFLAGS =  -r -k -d cpv -d
 Global: .MAKEFLAGS =  -r -k -d cpv -d 0
diff -r 14f148156703 -r c0869be04db2 usr.bin/make/unit-tests/var-eval-short.mk
--- a/usr.bin/make/unit-tests/var-eval-short.mk Tue Sep 07 18:02:46 2021 +0000
+++ b/usr.bin/make/unit-tests/var-eval-short.mk Tue Sep 07 20:41:58 2021 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: var-eval-short.mk,v 1.6 2021/09/06 19:38:30 rillig Exp $
+# $NetBSD: var-eval-short.mk,v 1.7 2021/09/07 20:41:58 rillig Exp $
 #
 # Tests for each variable modifier to ensure that they only do the minimum
 # necessary computations.  If the result of the expression is not needed, they
@@ -59,10 +59,12 @@
 .endif
 
 # Before var.c 1.856 from 2021-03-14, the modifier ':C' did not expand the
-# nested expression ${FAIL} and then tried to compile the unexpanded text as a
-# regular expression, which failed both because of the '{FAIL}', which is not
-# a valid repetition, and because of the '****', which are repeated
-# repetitions as well.
+# nested expression ${FAIL}, which is correct, and then tried to compile the
+# unexpanded text as a regular expression, which is unnecessary since the
+# right-hand side of the '&&' cannot influence the outcome of the condition.
+# Compiling the regular expression then failed both because of the '{FAIL}',
+# which is not a valid repetition of the form '{1,5}', and because of the
+# '****', which are repeated repetitions as well.
 # '${FAIL}'
 .if 0 && ${:Uword:C,${FAIL}****,,}
 .endif