Bug#389558: autoconf: AC_PROG_GCC_TRADITIONAL throws error in comparision

[Ralf Wildenhues]

[ apologies for the resend ]
[ this is http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=389558 ]

Hello,

* IOhannes m zmoelnig wrote on Wed, Sep 27, 2006 at 12:14:01PM CEST:
> Ralf Wildenhues wrote:
> 
> >Could you show the package, configure invocation and output where you
> >are experiencing this with, so we can decide which of the above is the
> >case?

> i just noticed that the actual line throwing the error is:
> 
>  if test $ac_cv_c_compiler_gnu = yes; then
> 
> after that it was simple to find the real source of troubles:
> i use autoconf/configure to configure a c++-application, so i only use 
> AC_PROG_CXX (and not AC_PROG_CC !) before calling 
> AC_PROG_GCC_TRADITIONAL (which i do for historical reasons...)

Well, then you can just remove that call of AC_PROG_GCC_TRADITIONAL.
First, with Autoconf-2.60, this macro is obsoleted anyway, then it was
ever only needed for dysfunctional `ioctl', see the manual:

|  -- Macro: AC_PROG_GCC_TRADITIONAL
|      Add `-traditional' to output variable `CC' if using the GNU C
|      compiler and `ioctl' does not work properly without
|      `-traditional'.  That usually happens when the fixed header files
|      have not been installed on an old system.
| 
|      This macro is obsolescent, since current versions of the GNU C
|      compiler fix the header files automatically when installed.

and I bet you're not going to need that anyway in your C++-only code.

> since ac_cv_c_compiler_gnu is obviously not set by AC_PROG_CXX (but only 
> by AC_PROG_CC), i get the following error (which was missing in the 
> initial report):
> 
> ./configure: line 3177: test: =: unary operator expected

But lastly, you may have a point, however small the relevance should be:
AC_PROG_GCC_TRADITIONAL should require AC_PROG_CC.  The error may be
reproduced with this configure.ac script:
  AC_INIT
  AC_PROG_CXX
  AC_LANG(C++)
  AC_PROG_GCC_TRADITIONAL

Autoconf folks: OK to apply?  Alternatively, how about if we just tag
the macro with a AC_DIAGNOSE([obsolete], ...)?

Cheers,
Ralf

        * lib/autoconf/c.m4 (AC_PROG_GCC_TRADITIONAL): Require
        AC_PROG_CC.
        Report by IOhannes m zmoelnig <address@hidden>.

Index: lib/autoconf/c.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/c.m4,v
retrieving revision 1.236
diff -u -r1.236 c.m4
--- lib/autoconf/c.m4   6 Oct 2006 17:43:55 -0000       1.236
+++ lib/autoconf/c.m4   11 Oct 2006 19:56:45 -0000
@@ -611,7 +611,8 @@
 # -----------------------
 AN_FUNCTION([ioctl],   [AC_PROG_GCC_TRADITIONAL])
 AC_DEFUN([AC_PROG_GCC_TRADITIONAL],
-[if test $ac_cv_c_compiler_gnu = yes; then
+[AC_REQUIRE([AC_PROG_CC])dnl
+if test $ac_cv_c_compiler_gnu = yes; then
     AC_CACHE_CHECK(whether $CC needs -traditional,
       ac_cv_prog_gcc_traditional,
 [  ac_pattern="Autoconf.*'x'"