Thank you, Ryan, for letting us know. This probably also impacts powerpc systems (or any that use modern gcc).
On Wed, Apr 8, 2026 at 4:17 PM Ryan Carsten Schmidt <[email protected]> wrote: > Heads up! The autoconf port was just updated to 2.73. One of the changes > in this version is that it defaults to C23 if the compiler supports it. > Xcode 26 clang supports C23 as do newer MacPorts clangs. > > C23 is not fully backward compatible with older C standards. Very old > ports that use autoreconf where no fixed upstream version is available may > need to have the appropriate "-std=" flag added to put the compiler into > whatever older mode it requires. > > Check the autoconf 2.73 release announcement: > > https://lists.gnu.org/archive/html/info-gnu/2026-03/msg00008.html > > > This is to announce the new stable release 2.73 of autoconf. > > > > Autoconf 2.73 is largely a bug-fix release; the most important change > > is improved support for the 2024 revision of the C standard (commonly > > known as "C23") and for compilers that default to that revision. We > > have also improved support for GNU Gettext and other major third-party > > extensions to the Autotools. > > > ** Backward incompatibilities > > > > *** AC_PROG_CC now prefers C23 if available. > > Older code may need to be updated, as C23 has removed old-style > > (K&R) function definitions and declarations, now uses type-generic > > functions for strchr and similar functions, and has new keywords > > alignas, alignof, bool, constexpr, false, nullptr, static_assert, > > thread_local, true, typeof, typeof_unqual. > > > > The shell variable $ac_prog_cc_stdc can now take the value ‘c23’. > > Configure scripts may need to be adjusted to handle this. It is > > likely to be more future-proof to check this variable for values > > that indicate the compiler is too *old*. > > > > *** AC_PROG_CC no longer checks __STDC__ or variable length arrays > (VLAs). > > This ports better to MSVC, which does not define __STDC__ and does > > not support VLAs. Although C99 requires VLAs, they are optional in > > C11 and later. Programs can use AC_C_VARARRAYS and __STDC_NO_VLA__ > > to use VLAs if available. > > > > *** AC_PROG_CXX no longer attempts to switch to C++98 or C++11. > > Instead, it uses the compiler's default, which you can override > > by configuring with something like CXX='g++ -std=gnu++11'. > > This reverts to Autoconf 2.69 behavior, and also fixes a bug where > > AC_PROG_CXX rejected C++20 compilers. > >
