AC_PROG_CC_C89 is not adding -std=c89 to CFLAGS

[Dimitrios Apostolou]

Hello list,

recent GCC versions default to C99 or even C11. I was expecting that 
adding AC_PROG_CC_C89 to configure.ac, would force C89, probably by using 
-std=gnu89. But this was not the case. Any ideas why?


Context is compiling a C program using a recent gcc on Solaris 10, 
resulted to this error:

/opt/csw/lib/gcc/i386-pc-solaris2.10/5.2.0/include-fixed/sys/feature_tests.h:346:2: 
error: #error "Compiler or options invalid for pre-UNIX 03 X/Open 
applications       and pre-2001 POSIX applications"


> From the header file:

#if defined(_STDC_C99) && (defined(__XOPEN_OR_POSIX) && !defined(_XPG6))
#error "Compiler or options invalid for pre-UNIX 03 X/Open applications \
        and pre-2001 POSIX applications"
#elif !defined(_STDC_C99) && \
        (defined(__XOPEN_OR_POSIX) && defined(_XPG6))
#error "Compiler or options invalid; UNIX 03 and POSIX.1-2001 applications 
\
        require the use of c99"
#endif


Thank you in advance,
Dimitris