[binutils-gdb] Fix GDB build: ELF support check & -lzstd

[Pedro Alves]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=16bd13978f3e02e869cea603579b9f60401ed61c

commit 16bd13978f3e02e869cea603579b9f60401ed61c
Author: Pedro Alves <pedro@palves.net>
Date:   Wed Sep 28 11:33:30 2022 +0100

    Fix GDB build: ELF support check & -lzstd
    
    GDB fails to build for me, on Ubuntu 20.04.  I get:
    
     ...
       CXXLD  gdb
     /usr/bin/ld: linux-tdep.o: in function `linux_corefile_thread(thread_info*, linux_corefile_thread_data*)':
     /home/pedro/gdb/binutils-gdb/src/gdb/linux-tdep.c:1831: undefined reference to `gcore_elf_build_thread_register_notes(gdbarch*, thread_info*, gdb_signal, bfd*, std::unique_ptr<char, gdb::xfree_deleter<char> >*, int*)'
     /usr/bin/ld: linux-tdep.o: in function `linux_make_corefile_notes(gdbarch*, bfd*, int*)':
     /home/pedro/gdb/binutils-gdb/src/gdb/linux-tdep.c:2117: undefined reference to `gcore_elf_make_tdesc_note(bfd*, std::unique_ptr<char, gdb::xfree_deleter<char> >*, int*)'
     collect2: error: ld returned 1 exit status
     make[2]: *** [Makefile:2149: gdb] Error 1
     make[2]: Leaving directory '/home/pedro/gdb/binutils-gdb/build/gdb'
     make[1]: *** [Makefile:11847: all-gdb] Error 2
     make[1]: Leaving directory '/home/pedro/gdb/binutils-gdb/build'
     make: *** [Makefile:1004: all] Error 2
    
    Those undefined functions exist in gdb/gcore-elf.c, which is only
    included in the build if GDB's configure thinks that the target you're
    configuring for is an ELF target.  GDB's configure thinks my system
    isn't ELF, which is incorrect.
    
    For the ELF support check, gdb/config.log shows:
    
     configure:17387: checking for ELF support in BFD
     configure:17407: gcc -o conftest -I/home/pedro/gdb/binutils-gdb/src/gdb/../include -I../bfd -I/home/pedro/gdb/binutils-gdb/src/gdb/../bfd -g3 -O0      -L../bfd -L../libiberty  -lzstd   conftest.c -lbfd -liberty -lz  -lncursesw -lm -ldl  >&5
     /usr/bin/ld: ../bfd/libbfd.a(compress.o): in function `decompress_contents':
     /home/pedro/gdb/binutils-gdb/src/bfd/compress.c:42: undefined reference to `ZSTD_decompress'
     /usr/bin/ld: /home/pedro/gdb/binutils-gdb/src/bfd/compress.c:44: undefined reference to `ZSTD_isError'
     /usr/bin/ld: ../bfd/libbfd.a(compress.o): in function `bfd_compress_section_contents':
     /home/pedro/gdb/binutils-gdb/src/bfd/compress.c:195: undefined reference to `ZSTD_compress'
     /usr/bin/ld: /home/pedro/gdb/binutils-gdb/src/bfd/compress.c:198: undefined reference to `ZSTD_isError'
     collect2: error: ld returned 1 exit status
     configure:17407: $? = 1
     ...
     configure:17417: result: no
    
    Note how above, in the gcc command line, "-lzstd" appears before
    "-lbfd".  That explain the link failure.  It should appear after, like
    -lz does.
    
    This commit fixes it, by moving ZSTD_LIBS from LDFLAGS to LIBS, next
    to -lz, in GDB_AC_CHECK_BFD, and regenerating gdb/configure.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29630
    Change-Id: I1f4128dde634e8ea04c9002904f1005a8b3a6863

Diff:
---
 gdb/acinclude.m4 | 4 ++--
 gdb/configure    | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
index 28846119dcb..62fa66c7af3 100644
--- a/gdb/acinclude.m4
+++ b/gdb/acinclude.m4
@@ -234,9 +234,9 @@ AC_DEFUN([GDB_AC_CHECK_BFD], [
   # always want our bfd.
   CFLAGS="-I${srcdir}/../include -I../bfd -I${srcdir}/../bfd $CFLAGS"
   ZLIBDIR=`echo $zlibdir | sed 's,\$(top_builddir)/,,g'`
-  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $ZSTD_LIBS $LDFLAGS"
+  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
-  LIBS="-lbfd -liberty -lz $intl $LIBS"
+  LIBS="-lbfd -liberty -lz $ZSTD_LIBS $intl $LIBS"
   AC_CACHE_CHECK(
     [$1],
     [$2],
diff --git a/gdb/configure b/gdb/configure
index 238b66f3c60..33677262783 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -17412,9 +17412,9 @@ WIN32LIBS="$WIN32LIBS $WIN32APILIBS"
   # always want our bfd.
   CFLAGS="-I${srcdir}/../include -I../bfd -I${srcdir}/../bfd $CFLAGS"
   ZLIBDIR=`echo $zlibdir | sed 's,\$(top_builddir)/,,g'`
-  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $ZSTD_LIBS $LDFLAGS"
+  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
-  LIBS="-lbfd -liberty -lz $intl $LIBS"
+  LIBS="-lbfd -liberty -lz $ZSTD_LIBS $intl $LIBS"
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ELF support in BFD" >&5
 $as_echo_n "checking for ELF support in BFD... " >&6; }
 if ${gdb_cv_var_elf+:} false; then :
@@ -17527,9 +17527,9 @@ fi
   # always want our bfd.
   CFLAGS="-I${srcdir}/../include -I../bfd -I${srcdir}/../bfd $CFLAGS"
   ZLIBDIR=`echo $zlibdir | sed 's,\$(top_builddir)/,,g'`
-  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $ZSTD_LIBS $LDFLAGS"
+  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
-  LIBS="-lbfd -liberty -lz $intl $LIBS"
+  LIBS="-lbfd -liberty -lz $ZSTD_LIBS $intl $LIBS"
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for Mach-O support in BFD" >&5
 $as_echo_n "checking for Mach-O support in BFD... " >&6; }
 if ${gdb_cv_var_macho+:} false; then :