[src/trunk]: src/usr.bin/make/unit-tests tests/make: finish a previously unfi...

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

details:   https://anonhg.NetBSD.org/src/rev/cf4e9bcba880
branches:  trunk
changeset: 1026378:cf4e9bcba880
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Nov 20 17:47:33 2021 +0000

description:
tests/make: finish a previously unfinished sentence in a comment

diffstat:

 usr.bin/make/unit-tests/var-op-expand.exp |   8 +++---
 usr.bin/make/unit-tests/var-op-expand.mk  |  36 ++++++++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 7 deletions(-)

diffs (72 lines):

diff -r 405ae06c66af -r cf4e9bcba880 usr.bin/make/unit-tests/var-op-expand.exp
--- a/usr.bin/make/unit-tests/var-op-expand.exp Sat Nov 20 17:27:46 2021 +0000
+++ b/usr.bin/make/unit-tests/var-op-expand.exp Sat Nov 20 17:47:33 2021 +0000
@@ -1,7 +1,7 @@
-make: "var-op-expand.mk" line 229: Unknown modifier "s,value,replaced,"
-make: "var-op-expand.mk" line 232: warning: XXX Neither branch should be taken.
-make: "var-op-expand.mk" line 237: Unknown modifier "s,value,replaced,"
-make: "var-op-expand.mk" line 238: warning: XXX Neither branch should be taken.
+make: "var-op-expand.mk" line 259: Unknown modifier "s,value,replaced,"
+make: "var-op-expand.mk" line 262: warning: XXX Neither branch should be taken.
+make: "var-op-expand.mk" line 267: Unknown modifier "s,value,replaced,"
+make: "var-op-expand.mk" line 268: warning: XXX Neither branch should be taken.
 make: Fatal errors encountered -- cannot continue
 make: stopped in unit-tests
 exit status 1
diff -r 405ae06c66af -r cf4e9bcba880 usr.bin/make/unit-tests/var-op-expand.mk
--- a/usr.bin/make/unit-tests/var-op-expand.mk  Sat Nov 20 17:27:46 2021 +0000
+++ b/usr.bin/make/unit-tests/var-op-expand.mk  Sat Nov 20 17:47:33 2021 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: var-op-expand.mk,v 1.13 2021/11/13 19:02:07 rillig Exp $
+# $NetBSD: var-op-expand.mk,v 1.14 2021/11/20 17:47:33 rillig Exp $
 #
 # Tests for the := variable assignment operator, which expands its
 # right-hand side.
@@ -212,7 +212,7 @@
 #
 # The assignment operator ':=' for the variable 'INDIRECT' could be a '=' as
 # well, it wouldn't make a difference in this case.  The crucial detail is the
-# assignment operator ':=' for the variable 'indirect', though.  During this
+# assignment operator ':=' for the variable 'indirect'.  During this
 # assignment, the variable modifier ':S,value,replaced,' is converted to
 # lowercase, which turns 'S' into 's', thus producing an unknown modifier.
 # In this case, make issues a warning, but in cases where the modifier
@@ -220,7 +220,37 @@
 # substitution like '.c=.o', and make would not issue a warning, leading to
 # silent unexpected behavior.
 #
-# As of 2021-11-13, the actual behavior is unexpected though since
+# As of 2021-11-20, the actual behavior is unexpected.  Fixing it is not
+# trivial.  When the assignment to 'indirect' takes place, the expressions
+# from the nested expression could be preserved, like this:
+#
+#      Start with:
+#
+#              indirect:=      ${INDIRECT:tl}
+#
+#      Since INDIRECT is defined, expand it, remembering that the modifier
+#      ':tl' must still be applied to the final result.
+#
+#              indirect:=      ${LATER:S,value,replaced,} \
+#                              OK \
+#                              ${LATER:value=sysv}
+#
+#      The variable 'LATER' is not defined.  An idea may be to append the
+#      remaining modifier ':tl' to each expression that is starting with an
+#      undefined variable, resulting in:
+#
+#              indirect:=      ${LATER:S,value,replaced,:tl} \
+#                              OK \
+#                              ${LATER:value=sysv:tl}
+#
+#      This would work for the first expression.  The second expression ends
+#      with the SysV modifier ':from=to', and when this modifier is parsed,
+#      it consumes all characters until the end of the expression, which in
+#      this case would replace the suffix 'value' with the literal 'sysv:tl',
+#      ignoring that the ':tl' was intended to be an additional modifier.
+#
+# Due to all of this, this surprising behavior is not easy to fix.
+#
 .undef LATER
 .undef later
 INDIRECT:=     ${LATER:S,value,replaced,} OK ${LATER:value=sysv}