If the current language is not C, the AC_PROG_CC_C_O macro will never- theless directly invoke the C compiler, but the file extensions used by the tests will be appropriate for the current language setting rather than for the C compiler.
In this case, the test may produce a false negative result if the C compiler cares about input file extensions (for example, when using the GNU Compiler Collection) or if the current language uses a different object file extension than the C compiler. * lib/autoconf/c.m4 (AC_PROG_CC_C_O): Add AC_LANG_ASSERT([C]) to help avoid possible false negatives. --- lib/autoconf/c.m4 | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4 index affd765..fcc5c88 100644 --- a/lib/autoconf/c.m4 +++ b/lib/autoconf/c.m4 @@ -589,6 +589,7 @@ fi # -------------- AC_DEFUN([AC_PROG_CC_C_O], [AC_REQUIRE([AC_PROG_CC])dnl +AC_LANG_ASSERT([C])dnl if test "x$CC" != xcc; then AC_MSG_CHECKING([whether $CC and cc understand -c and -o together]) else -- 1.8.1
