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 --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
index 28846119dcb82a52761cfc5bd33855ad67f8663a..62fa66c7af3013c0f0d91bd6a78f5bd5ceb04fe2 100644 (file)
--- 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 238b66f3c60e6842bd684fa773b31eb690387650..33677262783b6789e8e2289b204146ac3f2b89e1 100755 (executable)
--- 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 :