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make(1): add test for the $$ expression

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This commit is contained in:
rillig 2020-08-19 05:40:06 +00:00
parent 697a5bfd15
commit 57bd6e4e52
2 changed files with 26 additions and 2 deletions
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4
usr.bin/make/unit-tests/varname-dollar.exp
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@ -1 +1,5 @@
make: "varname-dollar.mk" line 16: dollar is $.
make: "varname-dollar.mk" line 17: dollar in braces is .
make: "varname-dollar.mk" line 25: dollar is $.
make: "varname-dollar.mk" line 26: dollar in braces is dollar.
exit status 0

24
usr.bin/make/unit-tests/varname-dollar.mk
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@ -1,9 +1,29 @@
# $NetBSD: varname-dollar.mk,v 1.2 2020/08/16 14:25:16 rillig Exp $
# $NetBSD: varname-dollar.mk,v 1.3 2020/08/19 05:40:06 rillig Exp $
#
# Tests for the expression "$$", which looks as if it referred to a variable,
# but simply expands to a single '$' sign.
#
# If there really were a special variable named '$', the expressions ${${DOLLAR}}
# and $$ would always expand to the same value.
# TODO: Implementation
# Using the dollar sign in variable names is tricky and not recommended.
# To see that using this variable indeed affects the variable '$', run the
# test individually with the -dv option.
DOLLAR= $$
# At this point, the variable '$' is not defined. Therefore the second line
# returns an empty string.
.info dollar is $$.
.info dollar in braces is ${${DOLLAR}}.
# Now overwrite the '$' variable to see whether '$$' really expands to that
# variable, or whether '$$' is handled by the parser.
${DOLLAR}= dollar
# At this point, the variable '$' is defined, therefore its value is printed
# in the second .info directive.
.info dollar is $$.
.info dollar in braces is ${${DOLLAR}}.
all:
@:;