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cautotoolsc11

Make autotools add --std=c11 to CFLAGS

There is no mention of a AC_PROG_CC_C11 analogue to AC_PROG_CC_C99.

How can I get my autotools project to put --std=c11 into CFLAGS?

Solution

  • Most simply by putting

    CFLAGS+=" -std=c11"

    into your configure.ac (in addition to AC_PROG_CC). configure.ac is a template for a shell script, so you can simply put shell code in it. In fact, all the AC_FOO_BAR m4 macros expand to shell code themselves.

    Caveat: This will not check whether your compiler actually supports the -std=c11 flag. If you want to check for that, you can use use AX_CHECK_COMPILE_FLAG from the autoconf archive:

    AX_CHECK_COMPILE_FLAG([-std=c11], [
  CFLAGS+=" -std=c11"
], [
  echo "C compiler cannot compile C11 code"
  exit -1
])

    ...although simply waiting until something fails in the compilation also works, I suppose. The error message will be nicer this way, though.