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author | Zack Weinberg <zackw@panix.com> | 2020-11-09 15:15:23 -0500 |
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committer | Zack Weinberg <zackw@panix.com> | 2020-11-09 15:15:23 -0500 |
commit | 3b411849a0f97d6531d6a671ba5d7bc50e268df1 (patch) | |
tree | 350f84cbf72a9255028df4fbad8e565ae090a847 /build-aux/config.sub | |
parent | d1a65dc04301a11b7fe33708489a9ab470cfe55f (diff) | |
download | autoconf-3b411849a0f97d6531d6a671ba5d7bc50e268df1.tar.gz |
m4sh: Require shell to support $(...) command substitution.
As of the 2020-11-07 update, config.sub and config.guess
unconditionally use $(...) command substitution; see
<https://lists.gnu.org/archive/html/config-patches/2020-11/msg00011.html>.
Therefore, add this to the set of required shell features, searched
for by _AS_DETECT_BETTER_SHELL. On a system where /bin/sh doesn’t
support $(...), $CONFIG_SHELL will be set to one that does (and the
primary configure script will be re-executed using that shell).
AC_CANONICAL_* use $CONFIG_SHELL to execute config.guess/sub, so they
will keep working. This also means that configure scripts and
third-party macros that use $(...) will quietly start working
correctly on such ancient systems.
The test code is simple, but sufficient to weed out Solaris 10’s
/bin/sh, which doesn’t support $(...) but *does* support shell
functions.
I’m not going to touch any of the existing uses of `...` command
substitution in Autoconf proper for now, but it might make sense to
bulk upgrade them early in the 2.71 release cycle; if nothing else,
it would remove a major obstacle to running shellcheck over our
scripts.
* lib/m4sugar/m4sh.m4 (_AS_MODERN_CMDSUBST_WORKS): New macro.
(AS_INIT, AS_SHELL_SANITIZE): Call _AS_DETECT_REQUIRED for
_AS_MODERN_CMDSUBST_WORKS.
* NEWS: Mention the requirement for $(...).
Diffstat (limited to 'build-aux/config.sub')
0 files changed, 0 insertions, 0 deletions