[src/trunk]: src/usr.bin/make/unit-tests make(1): add test demonstrating how ...

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

details:   https://anonhg.NetBSD.org/src/rev/08ec440acb64
branches:  trunk
changeset: 942481:08ec440acb64
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Nov 08 18:05:32 2020 +0000

description:
make(1): add test demonstrating how ':=' and ':@var@' interact

diffstat:

 usr.bin/make/unit-tests/varmod-loop.exp |   8 +++++
 usr.bin/make/unit-tests/varmod-loop.mk  |  45 ++++++++++++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 1 deletions(-)

diffs (71 lines):

diff -r 0d050cddc0d4 -r 08ec440acb64 usr.bin/make/unit-tests/varmod-loop.exp
--- a/usr.bin/make/unit-tests/varmod-loop.exp   Sun Nov 08 17:37:29 2020 +0000
+++ b/usr.bin/make/unit-tests/varmod-loop.exp   Sun Nov 08 18:05:32 2020 +0000
@@ -1,3 +1,11 @@
+ParseReadLine (115): 'USE_8_DOLLARS=   ${:U1:@var@${8_DOLLARS}@} ${8_DOLLARS} $$$$$$$$'
+CondParser_Eval: ${USE_8_DOLLARS} != "\$\$\$\$ \$\$\$\$ \$\$\$\$"
+lhs = "$$$$ $$$$ $$$$", rhs = "$$$$ $$$$ $$$$", op = !=
+ParseReadLine (120): 'SUBST_CONTAINING_LOOP:= ${USE_8_DOLLARS}'
+CondParser_Eval: ${SUBST_CONTAINING_LOOP} != "\$\$ \$\$\$\$ \$\$\$\$"
+lhs = "$$ $$$$ $$$$", rhs = "$$ $$$$ $$$$", op = !=
+ParseReadLine (145): '.MAKEFLAGS: -d0'
+ParseDoDependency(.MAKEFLAGS: -d0)
 :+one+ +two+ +three+:
 :x1y x2y x3y:
 :x1y x2y x3y:
diff -r 0d050cddc0d4 -r 08ec440acb64 usr.bin/make/unit-tests/varmod-loop.mk
--- a/usr.bin/make/unit-tests/varmod-loop.mk    Sun Nov 08 17:37:29 2020 +0000
+++ b/usr.bin/make/unit-tests/varmod-loop.mk    Sun Nov 08 18:05:32 2020 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: varmod-loop.mk,v 1.6 2020/11/03 18:21:36 rillig Exp $
+# $NetBSD: varmod-loop.mk,v 1.7 2020/11/08 18:05:32 rillig Exp $
 #
 # Tests for the :@var@...${var}...@ variable modifier.
 
@@ -100,3 +100,46 @@
 .if defined(var)
 .  error
 .endif
+
+# Assignment using the ':=' operator, combined with the :@var@ modifier
+#
+8_DOLLARS=     $$$$$$$$
+# This string literal is written with 8 dollars, and this is saved as the
+# variable value.  But as soon as this value is evaluated, it goes through
+# Var_Subst, which replaces each '$$' with a single '$'.  This could be
+# prevented by VARE_KEEP_DOLLAR, but that flag is usually removed before
+# expanding subexpressions.  See ApplyModifier_Loop and ParseModifierPart
+# for examples.
+#
+.MAKEFLAGS: -dcp
+USE_8_DOLLARS= ${:U1:@var@${8_DOLLARS}@} ${8_DOLLARS} $$$$$$$$
+.if ${USE_8_DOLLARS} != "\$\$\$\$ \$\$\$\$ \$\$\$\$"
+.  error
+.endif
+#
+SUBST_CONTAINING_LOOP:= ${USE_8_DOLLARS}
+# The ':=' assignment operator evaluates the variable value using the flag
+# VARE_KEEP_DOLLAR, which means that some dollar signs are preserved, but not
+# all.  The dollar signs in the top-level expression and in the indirect
+# ${8_DOLLARS} are preserved.
+#
+# The variable modifier :@var@ does not preserve the dollar signs though, no
+# matter in which context it is evaluated.  What happens in detail is:
+# First, the modifier part "${8_DOLLARS}" is parsed without expanding it.
+# Next, each word of the value is expanded on its own, and at this moment
+# in ApplyModifier_Loop, the VARE_KEEP_DOLLAR flag is not passed down to
+# ModifyWords, resulting in "$$$$" for the first word of USE_8_DOLLARS.
+#
+# The remaining words of USE_8_DOLLARS are not affected by any variable
+# modifier and are thus expanded with the flag VARE_KEEP_DOLLAR in action.
+# The variable SUBST_CONTAINING_LOOP therefore gets assigned the raw value
+# "$$$$ $$$$$$$$ $$$$$$$$".
+#
+# The variable expression in the condition then expands this raw stored value
+# once, resulting in "$$ $$$$ $$$$".  The effects from VARE_KEEP_DOLLAR no
+# longer take place since they had only been active during the evaluation of
+# the variable assignment.
+.if ${SUBST_CONTAINING_LOOP} != "\$\$ \$\$\$\$ \$\$\$\$"
+.  error
+.endif
+.MAKEFLAGS: -d0