Re: ac_cv_prog_gcc

[Akim Demaille]

| Hi,
| With autoconf-2.13, I have been using constructs like the one below
| to detect whether gcc is used:
| [Similar constructs are used in libiberty, libgloss, newlib and
| Cygwin's winsup]
| 
| if test $ac_cv_prog_gcc = yes; then
| # do something
| fi
| 
| This test relies on the value of ac_cv_prog_gcc. With CVS-autoconf,
| however,
| 
| if test $ac_cv_prog_gcc = yes;
| 
| gets expanded into
| 
| if test $ac_cv_c_compiler_gnu() = yes;

Heck.  Thanks for noticing :(

| I am not sure if this is a valid shell expression at all. At least
| it doesn't give the expected result and breaks configure scripts
| which have been working with autoconf-2.13.

Yep, but these almost-invalid scripts are responsible for our backward
compatibility nightmare: ac_cv_prog_gcc has *never* been documented,
while GCC, GXX and G77 have always been.

| [Yes, I know, I could have used $GCC instead of ac_cv_prog_gcc :)]

Oops.  We agree :)