Re: _AC_PROG_CC_C89 enhancement

[Paul Eggert]

address@hidden (Larry Jones) writes:

> The IBM C compiler for AIX has a default mode that's almost, but not
> quite, C89.  The differences mostly involve the preprocessor.  In
> particular, macro parameters are substituted inside character constants
> and string literals, which can be quite surprising if you're not
> expecting it.  The current autoconf _AC_PROG_CC_C89 macro does not
> detect this and thus does not add the appropriate flag to CC to fix it. 
> Here's a fix:

Thanks very much; that's a subtle one that (as you noted on
bug-gnulib) breaks real software.  I installed it.

I assume that _AC_PROG_CC_C99 does not need a similar patch because
the default mode already doesn't pass that test.  If that assumption
is incorrect, please let us know.