[PATCH] gdb/gdbserver: switch to AC_CONFIG_MACRO_DIRS

[Simon Marchi]

On 2021-06-17 12:21 a.m., Mike Frysinger wrote:
> On 16 Jun 2021 22:30, Simon Marchi wrote:
>> On 2021-06-15 1:44 a.m., Mike Frysinger via Gdb-patches wrote:
>>> These dirs don't use automake, so use AC_CONFIG_MACRO_DIRS to specify
>>> ../config as a search dir for m4 macros.  This allows removal of a lot
>>> of hand-written m4_include's from acinclude.m4 files, and simplifies
>>> use of `aclocal` or `autoreconf` as manual -I is not needed.
>>
>> For some reason, I get this when reconfiguring gdb:
>>
>>     configure.ac:531: warning: macro 'AM_ICONV' not found in library
>>
>> The result looks ok, the resulting configure looks fine, but if you
>> happen to know why...
> 
> i don't know why automake is able to find some of the ../config/ m4 files
> just fine, but a few others it barfs on.  i don't see the warning because
> i have gettext installed and automake finds the system iconv.m4.

There seems to be a special case for printing that warning for AM_*
macros:

https://github.com/autotools-mirror/automake/blob/e7724fb1b7b97f662caf154414e6f71ffcbd966c/bin/aclocal.in#L528-L540

I debugged aclocal as much as I could, and it seems to find AM_ICONV
just fine, with --verbose I see:

  aclocal: found macro AM_ICONV in ../config/iconv.m4: 104

Also, note that with `aclocal -I ../config` I do not see the warning...
but aclocal does support AC_CONFIG_MACRO_DIRS, so this difference is
surprising.

So I'd be tempted to call that an aclocal bug, although a benign one.
I'd suggest still just doing the right thing and removing all the
../config/* includes, and just ignore the warnings.  I'll try to open an
automake bug or ask on the mailing list eventually.

Simon