diff options
Diffstat (limited to 'configure.in')
| -rw-r--r-- | configure.in | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/configure.in b/configure.in index ee85d686e21..a4e36c86c7a 100644 --- a/configure.in +++ b/configure.in @@ -414,6 +414,26 @@ else fi fi +# We use C constructs that became invalid in C23. Check if the compiler +# reports a standard higher than C17, with the flags selected above (so the +# user can control the language level explicitly to avoid the gcc/clang-only +# fallback logic below if preferred). +AC_MSG_CHECKING([whether $CC reports a C standard higher than ISO C17]) +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [@%:@if __STDC_VERSION__ > 201710L +choke me +@%:@endif])], [POSTC17=no], [POSTC17=yes]) +AC_MSG_RESULT(${POSTC17}) + +# If a too recent standard was detected with the user's CFLAGS, try asking for +# C17 with GNU extensions explicitly. +if test "$POSTC17" = yes; then + old_CFLAGS="$CFLAGS" + PGAC_PROG_CC_CFLAGS_OPT([-std=gnu17]) + if test "$CFLAGS" = "$old_CFLAGS"; then + AC_MSG_ERROR([cannot proceed]) + fi +fi + # CFLAGS we determined above will be added back at the end user_CFLAGS=$CFLAGS CFLAGS="" |