Re: Checking stderr form autoconf and autoheader

[Akim Demaille]

| There is indeed circular breakage in Autoconf (if it's what you understand
| under the term "circular breakage"). We should fix it first and then test.
| 
| $ cat >configure.in <<EOF
| > AC_INIT
| > AC_C_CONST
| > AC_OUTPUT
| > EOF
| $ autoconf
| configure.in:2: warning: AC_C_CONST was called before AC_PROG_CC_STDC

That's indeed what I'm referring to.  AC_C_CONST should just not
exists.  But it's too complex for us to solve this issue for 2.50,
that's definitely a 2.51 issue.

| Another problem is that two very different warnings belong to the same
| class "syntax" - unnecessary escapes in messages and incorrect order of
| tests.
| 
| We need to separate the later ones to a separate category, let's name it
| "order". It should be on by default.

I think it's OK to keep them together.  Too many choices are a
misfeature IMHO.

| On another hand, I'd like to turn off warnings about backslashes by
| default. The problem is that they are needed for Autoconf-2.13. They are
| obsolete, but they need to be tolerated if backward compatability is
| desired.

If you are really annoyed with this, classify them as `obsolete' for
2.50, and we will move them as `syntax' in 2.51.

        Akim