Re: [PATCH] gdb: use libtool in GDB_AC_CHECK_BFD

["Jose E. Marchesi" <jose.marchesi@oracle.com>]

> On 11/7/22 14:46, Jose E. Marchesi via Gdb-patches wrote:
>> The GDB_AC_CHECK_BFD macro defined in gdb/acinclude.m4 uses the
>> AC_LINK_IFELSE autoconf macro in order to link a simple program to
>> check features of libbfd.
>> 
>> If libbfd's link dependencies change, it was necessary to reflect them
>> either in the definition of the macro, or as a consequence of checking
>> for them with an autoconf macro resulting in an addition to LIBS.
>> 
>> This patch modifies the definition of the GDB_CHECK_BFD macro in order
>> to use libtool to perform the test link.  This makes it possible to
>> not have to list dependencies of libbfd (which are indirect to GDB) at
>> all.
>> 
>> After this patch:
>> 
>>   configure:28555: checking for ELF support in BFD
>>   configure:28575: ./libtool --quiet --mode=link gcc -o conftest \
>>                    -I../../gdb/../include -I../bfd -I../../gdb/../bfd
>>                    -g -O2 -L../bfd -L../libiberty -L../zlib
>>                    conftest.c \
>>                    -lbfd -liberty -lz   -lncursesw -lm -ldl  >&5
>>   configure:28575: $? = 0
>>   configure:28585: result: yes
>> ---
>>  gdb/acinclude.m4 |    3 +
>>  gdb/configure    | 1640 ++++++++++++++++++++++++++++++++++++++++++++++
>>  gdb/configure.ac |    3 +
>>  3 files changed, 1646 insertions(+)
>> 
>> diff --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
>> index 62fa66c7af3..bbe86f51f4d 100644
>> --- a/gdb/acinclude.m4
>> +++ b/gdb/acinclude.m4
>> @@ -229,6 +229,7 @@ AC_DEFUN([GDB_AC_CHECK_BFD], [
>>    OLD_CFLAGS=$CFLAGS
>>    OLD_LDFLAGS=$LDFLAGS
>>    OLD_LIBS=$LIBS
>> +  OLD_CC=$CC
>>    # Put the old CFLAGS/LDFLAGS last, in case the user's (C|LD)FLAGS
>>    # points somewhere with bfd, with -I/foo/lib and -L/foo/lib.  We
>>    # always want our bfd.
>> @@ -237,6 +238,7 @@ AC_DEFUN([GDB_AC_CHECK_BFD], [
>>    LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
>>    intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
>>    LIBS="-lbfd -liberty -lz $ZSTD_LIBS $intl $LIBS"
>
> So, can we remove $ZSTD_LIBS ands -lz here?  I think GDB only needs them
> through BFD.  And actually, can we remove them from gdb/Makefile.in too?

In the context of this macro, yes, we can remove -lz and $ZSTD_LIBS from
there.  Will do, test, an send a new version.

About gdb/Makefile.in... dunno, $(ZLIB) is included in CLIBS.  This
makes me think GDB uses zlib directly?

If it doesn't, I think you can remove:

1) The calls to AM_ZLIB and AC_ZSTD from gdb/configure.ac.
2) The definition of ZLIB and ZLIBINC from gdb/Makefile.in
3) ../config/zlib.m4 from aclocal_m4_deps in gdb/Makefile.in