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| author | Eric Blake <eblake@redhat.com> | 2015-04-15 16:31:34 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2015-04-21 06:15:35 -0600 |
| commit | 76754e04fce5f6a7701bec57b057020585df2ae3 (patch) | |
| tree | dc367be3756d07fa8f3b644bc6f8f7b50f5099e4 /configure.ac | |
| parent | 7bc2c5623d2fed6421bf95279e5d610ed8dbaa50 (diff) | |
| download | autoconf-76754e04fce5f6a7701bec57b057020585df2ae3.tar.gz | |
lib: use shorter way to test if variable is set
Based on an idea by Bernhard Reutner-Fischer.
We frequently used the idiom of 'test "${var+set}" = set' to
test if $var was set to a non-empty string, but this can portably
be trimmed to a more compact 'test ${var+y}' for a smaller
configure file. Testing that a variable is not set can be done
with '${var+false} :' (although the value of $? is not reliably
1 when the variable is set).
The code for AS_VAR_TEST_SET already used the form '${var+:} false',
but it is slightly longer, and does not guarantee $? of 1.
Tested on coreutils, where the resulting configure file is about
1k smaller.
* doc/autoconf.texi (Shell Substitutions): Prefer shorter sequence
for testing if a variable is set.
(Limitations of Builtins) <test (strings)>: Document it.
* configure.ac: Use it.
* lib/autoconf/c.m4 (_AC_PROG_CC_G, _AC_PROG_CXX_G)
(_AC_PROG_OBJC_G, _AC_PROG_OBJCXX_G): Likewise.
* lib/autoconf/fortran.m4 (_AC_PROG_FC_G): Likewise.
* lib/autoconf/general.m4 (_AC_ENABLE_IF_ACTION, AC_CACHE_SAVE):
Likewise.
* lib/autoconf/lang.m4 (_AC_COMPILER_EXEEXT_DEFAULT): Likewise.
* lib/autoconf/programs.m4 (AC_PROG_INSTALL, AC_PROG_MKDIR_P)
(_AC_PROG_LEX_YYTEXT_DECL): Likewise.
* lib/autoconf/status.m4 (_AC_OUTPUT_MAIN_LOOP): Likewise.
* lib/autotest/general.m4 (AT_INIT): Likewise.
* tests/base.at (AC_CACHE_CHECK): Likewise.
* tests/m4sh.at (LINENO): Likewise.
* lib/m4sugar/m4sh.m4 (_AS_BOURNE_COMPATIBLE)
(_AS_DETECT_BETTER_SHELL, _AS_SHELL_SANITIZE)
(_AS_PATH_SEPARATOR_PREPARE): Likewise.
(AS_VAR_TEST_SET): Use shorter sequence.
Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/configure.ac b/configure.ac index 2709a0d1..e7029ebc 100644 --- a/configure.ac +++ b/configure.ac @@ -61,9 +61,9 @@ AC_CACHE_CHECK([whether /bin/sh -n is known to work], [ac_cv_sh_n_works], [if ( unset BASH_VERSION ZSH_VERSION /bin/sh -c ' - test -n "${BASH_VERSION+set}" || # Bash - test -n "${KSH_VERSION+set}" || # pdksh - test -n "${ZSH_VERSION+set}" || # zsh + test ${BASH_VERSION+y} || # Bash + test ${KSH_VERSION+y} || # pdksh + test ${ZSH_VERSION+y} || # zsh test -n "${.sh.version}" # ksh93; put this last since its syntax is dodgy ' ) 2>/dev/null |