From http://sources.redhat.com/ml/libc-alpha/2002-06/msg00006.html

Message-ID: <15612.44195.299251.921969@honolulu.ilog.fr>
Date: Tue, 4 Jun 2002 14:03:47 +0200 (CEST)
From: Bruno Haible <bruno at clisp dot org>
To: libc-alpha at sources dot redhat dot com
Subject: link_warning fix


Hi,

While cross-compiling glibc-2.2.5 for target=cris-linux using gcc-3.1 and
binutils-2.12.90.0.7, I get an error

cris-linux-gcc ../sysdeps/unix/sysv/linux/sigstack.c -c -O2 -Wall -Winline -Wstrict-prototypes -Wwrite-strings -g      -I../include -I. -I/backup/cross-build/build-glibc-cris/signal -I.. -I../libio  -I/backup/cross-build/build-glibc-cris -I../sysdeps/cris/elf -I../linuxthreads/sysdeps/unix/sysv/linux -I../linuxthreads/sysdeps/pthread -I../sysdeps/pthread -I../linuxthreads/sysdeps/unix/sysv -I../linuxthreads/sysdeps/unix -I../linuxthreads/sysdeps/cris -I../sysdeps/unix/sysv/linux/cris -I../sysdeps/unix/sysv/linux -I../sysdeps/gnu -I../sysdeps/unix/common -I../sysdeps/unix/mman -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/cris -I../sysdeps/wordsize-32 -I../sysdeps/ieee754/flt-32 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754 -I../sysdeps/generic/elf -I../sysdeps/generic  -nostdinc -isystem /cross/cris-linux-tools/lib/gcc-lib/cris-linux/3.1/include -isystem /cross/cris-linux/include -D_LIBC_REENTRANT -include ../include/libc-symbols.h     -o /backup/cross-build/build-glibc-cris/signal/sigstack.o
/tmp/cca7qZyI.s: Assembler messages:
/tmp/cca7qZyI.s:87: Warning: rest of line ignored; first ignored character is `,'
/tmp/cca7qZyI.s:87: Error: Unknown opcode: `progbits'
make[2]: *** [/backup/cross-build/build-glibc-cris/signal/sigstack.o] Fehler 1


The reason is that the .s file contains the following.

...
	.size	sigstack,.Lfe1-sigstack
#APP
	.section .gnu.warning.sigstack
	.previous
#NO_APP
	.section	.gnu.warning.sigstack
	#,"a",@progbits
	.align 2
	.type	__evoke_link_warning_sigstack,@object
...

and comments (introduced by '#') are recognized by the assembler only after
#APP, not after #NO_APP. The workaround is to add '#APP' to the fake section
name. The following patch works for me.

2002-06-02  Bruno Haible  <bruno@clisp.org>

	* include/libc-symbols.h (__as_app_line): New macro.
	(link_warning): Emit #APP line to turn comment recognition on.

*** glibc-2.2.5/include/libc-symbols.h.bak	2001-08-04 01:02:52.000000000 +0200
--- glibc-2.2.5/include/libc-symbols.h	2002-06-02 16:22:15.000000000 +0200
***************
*** 207,224 ****
  #   define __make_section_unallocated(section_string)
  #  endif
  
! /* Tacking on "\n\t#" to the section name makes gcc put it's bogus
!    section attributes on what looks like a comment to the assembler.  */
  #  ifdef HAVE_SECTION_QUOTES
  #   define link_warning(symbol, msg) \
    __make_section_unallocated (".gnu.warning." #symbol) \
!   static const char __evoke_link_warning_##symbol[]	\
!     __attribute__ ((section (".gnu.warning." #symbol "\"\n\t#\""))) = msg;
  #  else
  #   define link_warning(symbol, msg) \
    __make_section_unallocated (".gnu.warning." #symbol) \
!   static const char __evoke_link_warning_##symbol[]	\
!     __attribute__ ((section (".gnu.warning." #symbol "\n\t#"))) = msg;
  #  endif
  # else /* Not ELF: a.out */
  #  ifdef HAVE_XCOFF
--- 207,235 ----
  #   define __make_section_unallocated(section_string)
  #  endif
  
! /* Tacking on "\n\t#" to the section name makes gcc put its bogus
!    section attributes on what looks like a comment to the assembler.
!    Furthermore, with gas, we need to add a "#APP" line so the comment
!    is recognized as such.  */
! #  ifdef HAVE_GNU_AS
! #   define __as_app_line "#APP\n"
! #  else
! #   define __as_app_line ""
! #  endif
  #  ifdef HAVE_SECTION_QUOTES
  #   define link_warning(symbol, msg) \
    __make_section_unallocated (".gnu.warning." #symbol) \
!   static const char __evoke_link_warning_##symbol[]			 \
!     __attribute__							 \
!       ((section (".gnu.warning." #symbol "\"\n" __as_app_line "\t#\""))) \
!     = msg;
  #  else
  #   define link_warning(symbol, msg) \
    __make_section_unallocated (".gnu.warning." #symbol) \
!   static const char __evoke_link_warning_##symbol[]			\
!     __attribute__							\
!       ((section (".gnu.warning." #symbol "\n" __as_app_line "\t#")))	\
!     = msg;
  #  endif
  # else /* Not ELF: a.out */
  #  ifdef HAVE_XCOFF