Module Name: src
Committed By: rillig
Date: Fri Sep 25 05:56:59 UTC 2020
Modified Files:
src/distrib/sets/lists/tests: mi
src/usr.bin/make/unit-tests: Makefile
Added Files:
src/usr.bin/make/unit-tests: varparse-undef-partial.exp
varparse-undef-partial.mk
Log Message:
make(1): add test for partial expansion of undefined variables
To generate a diff of this commit:
cvs rdiff -u -r1.927 -r1.928 src/distrib/sets/lists/tests/mi
cvs rdiff -u -r1.148 -r1.149 src/usr.bin/make/unit-tests/Makefile
cvs rdiff -u -r0 -r1.1 src/usr.bin/make/unit-tests/varparse-undef-partial.exp \
src/usr.bin/make/unit-tests/varparse-undef-partial.mk
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/distrib/sets/lists/tests/mi
diff -u src/distrib/sets/lists/tests/mi:1.927 src/distrib/sets/lists/tests/mi:1.928
--- src/distrib/sets/lists/tests/mi:1.927 Wed Sep 23 03:33:54 2020
+++ src/distrib/sets/lists/tests/mi Fri Sep 25 05:56:59 2020
@@ -1,4 +1,4 @@
-# $NetBSD: mi,v 1.927 2020/09/23 03:33:54 rillig Exp $
+# $NetBSD: mi,v 1.928 2020/09/25 05:56:59 rillig Exp $
#
# Note: don't delete entries from here - mark them as "obsolete" instead.
#
@@ -5172,6 +5172,8 @@
./usr/tests/usr.bin/make/unit-tests/varname.mk tests-usr.bin-tests compattestfile,atf
./usr/tests/usr.bin/make/unit-tests/varparse-dynamic.exp tests-usr.bin-tests compattestfile,atf
./usr/tests/usr.bin/make/unit-tests/varparse-dynamic.mk tests-usr.bin-tests compattestfile,atf
+./usr/tests/usr.bin/make/unit-tests/varparse-undef-partial.exp tests-usr.bin-tests compattestfile,atf
+./usr/tests/usr.bin/make/unit-tests/varparse-undef-partial.mk tests-usr.bin-tests compattestfile,atf
./usr/tests/usr.bin/make/unit-tests/varquote.exp tests-usr.bin-tests compattestfile,atf
./usr/tests/usr.bin/make/unit-tests/varquote.mk tests-usr.bin-tests compattestfile,atf
./usr/tests/usr.bin/make/unit-tests/varshell.exp tests-usr.bin-tests compattestfile,atf
Index: src/usr.bin/make/unit-tests/Makefile
diff -u src/usr.bin/make/unit-tests/Makefile:1.148 src/usr.bin/make/unit-tests/Makefile:1.149
--- src/usr.bin/make/unit-tests/Makefile:1.148 Wed Sep 23 07:54:08 2020
+++ src/usr.bin/make/unit-tests/Makefile Fri Sep 25 05:56:59 2020
@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.148 2020/09/23 07:54:08 rillig Exp $
+# $NetBSD: Makefile,v 1.149 2020/09/25 05:56:59 rillig Exp $
#
# Unit tests for make(1)
#
@@ -347,6 +347,7 @@ TESTS+= varname-makeflags
TESTS+= varname-pwd
TESTS+= varname-vpath
TESTS+= varparse-dynamic
+TESTS+= varparse-undef-partial
TESTS+= varquote
TESTS+= varshell
Added files:
Index: src/usr.bin/make/unit-tests/varparse-undef-partial.exp
diff -u /dev/null src/usr.bin/make/unit-tests/varparse-undef-partial.exp:1.1
--- /dev/null Fri Sep 25 05:56:59 2020
+++ src/usr.bin/make/unit-tests/varparse-undef-partial.exp Fri Sep 25 05:56:59 2020
@@ -0,0 +1 @@
+exit status 0
Index: src/usr.bin/make/unit-tests/varparse-undef-partial.mk
diff -u /dev/null src/usr.bin/make/unit-tests/varparse-undef-partial.mk:1.1
--- /dev/null Fri Sep 25 05:56:59 2020
+++ src/usr.bin/make/unit-tests/varparse-undef-partial.mk Fri Sep 25 05:56:59 2020
@@ -0,0 +1,64 @@
+# $NetBSD: varparse-undef-partial.mk,v 1.1 2020/09/25 05:56:59 rillig Exp $
+
+# When an undefined variable is expanded in a ':=' assignment, only the
+# initial '$' of the variable expression is skipped by the parser, while
+# the remaining expression is evaluated. In edge cases this can lead to
+# a completely different interpretation of the partially expanded text.
+
+LIST= ${DEF} ${UNDEF} ${VAR.${PARAM}} end
+DEF= defined
+PARAM= :Q
+
+# The expression ${VAR.{PARAM}} refers to the variable named "VAR.:Q",
+# with the ":Q" being part of the name. This variable is not defined,
+# therefore the initial '$' of that whole expression is skipped by the
+# parser (see Var_Subst, the Buf_AddByte in the else branch) and the rest
+# of the expression is expanded as usual.
+#
+# The resulting variable expression is ${VAR.:Q}, which means that the
+# interpretation of the ":Q" has changed from being part of the variable
+# name to being a variable modifier. This is a classical code injection.
+EVAL:= ${LIST}
+.if ${EVAL} != "defined end"
+. error ${EVAL}
+.endif
+
+# Define the possible outcomes, to see which of them gets expanded.
+VAR.= var-dot without parameter
+${:UVAR.\:Q}= var-dot with parameter :Q
+
+# At this point, the variable "VAR." is defined, therefore the expression
+# ${VAR.:Q} is expanded as usual.
+.if ${EVAL} != "defined var-dot\\ without\\ parameter end"
+. error ${EVAL}
+.endif
+
+# In contrast to the previous line, evaluating the original LIST again now
+# produces a different result since the ":Q" has already been inserted
+# literally into the expression. The variable named "VAR.:Q" is defined,
+# therefore it is resolved as usual. The ":Q" is interpreted as part of the
+# variable name, as would be expected from reading the variable expression.
+EVAL:= ${LIST}
+.if ${EVAL} != "defined var-dot with parameter :Q end"
+. error ${EVAL}
+.endif
+
+# It's difficult to decide what the best behavior is in this situation.
+# Should the whole expression be skipped for now, or should the inner
+# subexpressions be expanded already?
+#
+# Example 1:
+# CFLAGS:= ${CFLAGS:N-W*} ${COPTS.${COMPILER}}
+#
+# The variable COMPILER typically contains an identifier and the variable is
+# not modified later. In this practical case, it does not matter whether the
+# expression is expanded early, or whether the whole ${COPTS.${COMPILER}} is
+# expanded as soon as the variable COPTS.${COMPILER} becomes defined. The
+# expression ${COMPILER} would be expanded several times, but in this simple
+# scenario there would not be any side effects.
+#
+# TODO: Add a practical example where early/lazy expansion actually makes a
+# difference.
+
+all:
+ @:
