AC_COMPILE_WARNINGS, VL_PROG_CC_WARNINGS, AX_CFLAGS_WARN_ALL{, _ANSI}

[Reuben Thomas]

This is the most egregious case of overlap that springs out at me.

The comments for AX_CFLAGS_WARN_ALL say:

#   This macro is directly derived from VL_PROG_CC_WARNINGS which is split
#   up into two AX_CFLAGS_WARN_ALL and AX_CFLAGS_WARN_ALL_ANSI

The list of compilers they deal with is identical. Further, they both
make the same design mistake, which is to conflate (in different ways)
detection of warning flags with detection of ANSI/ISO-compliance
flags, which should be done by AC_PROG_CC_STDC{,_C89}.

AC_COMPILE_WARNINGS seems only to deal with GCC, and have no other
functionality.

Therefore, I suggest removing AC_COMPILE_WARNINGS and
VL_PROG_CC_WARNINGS, and AX_CFLAGS_WARN_ALL_ANSI, leaving just
AX_CFLAGS_WARN_ALL. Then, make a new macro from
AX_CFLAGS_WARN_ALL_ANSI called AX_PROG_CC_STDC_C89 (as far as I can
see, we're talking about C89, not C99 compliance here) which has
exactly the same interface as AC_PROG_CC_STDC_C89, but works with more
compilers. It should be merged into autoconf (as should
AX_CFLAGS_WARN_ALL, it's exactly the sort of thing that I need, at
least!).

How does this sounds as a plan?

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