[Bug debug/98708] New: [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one

[Bug debug/98708] New: [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

            Bug ID: 98708
           Summary: [11 Regression] cxx11-ios_failure-lt.s:36733: Error:
                    file number less than one
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

On Linux/x86-64, r11-6755 gave

cxx11-ios_failure-lt.s: Assembler messages:
cxx11-ios_failure-lt.s:36733: Error: file number less than one
make[9]: *** [Makefile:865: cxx11-ios_failure.lo] Error 1

  14         .file 1 "../../../../../src-master/libstdc++-v3/src/c++11/cxx11-io
     s_failure.cc"
......

36733         .file 0
"/export/gnu/import/git/gcc-test-master-intel64-native/bld     
/x86_64-pc-linux-gnu/libstdc++-v3/src/c++11" "../../../../../src-master/li     
bstdc++-v3/src/c++11/cxx11-ios_failure.cc"
36734         .section        .debug_str,"MS",@progb

r6752 is OK.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |mark at gcc dot gnu.org
   Last reconfirmed|                            |2021-01-17

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
This is with binutils master.  I think 2.36 branch may have the same issue.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[11 Regression]             |[11 Regression]
                   |cxx11-ios_failure-lt.s:3673 |cxx11-ios_failure-lt.s:3673
                   |3: Error: file number less  |3: Error: file number less
                   |than one                    |than one by r11-6755

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
/bin/sh ../../libtool --tag CXX --tag disable-shared   --mode=compile
/export/gnu/import/git/gcc-test-master-intel64-native/bld/./gcc/xgcc
-shared-libgcc
-B/export/gnu/import/git/gcc-test-master-intel64-native/bld/./gcc -nostdinc++
-L/export/gnu/import/git/gcc-test-master-intel64-native/bld/x86_64-pc-linux-gnu/libstdc++-v3/src
-L/export/gnu/import/git/gcc-test-master-intel64-native/bld/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs
-L/export/gnu/import/git/gcc-test-master-intel64-native/bld/x86_64-pc-linux-gnu/libstdc++-v3/libsupc++/.libs
-B/usr/11.0.0/x86_64-pc-linux-gnu/bin/ -B/usr/11.0.0/x86_64-pc-linux-gnu/lib/
-isystem /usr/11.0.0/x86_64-pc-linux-gnu/include -isystem
/usr/11.0.0/x86_64-pc-linux-gnu/sys-include   -fno-checking
-I/export/gnu/import/git/gcc-test-master-intel64-native/src-master/libstdc++-v3/../libgcc
-I/export/gnu/import/git/gcc-test-master-intel64-native/bld/x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu
-I/export/gnu/import/git/gcc-test-master-intel64-native/bld/x86_64-pc-linux-gnu/libstdc++-v3/include
-I/export/gnu/import/git/gcc-test-master-intel64-native/src-master/libstdc++-v3/libsupc++
  -std=gnu++11 -prefer-pic -D_GLIBCXX_SHARED -fno-implicit-templates  -Wall
-Wextra -Wwrite-strings -Wcast-qual -Wabi=2  -fdiagnostics-show-location=once  
-ffunction-sections -fdata-sections  -frandom-seed=cxx11-ios_failure.lo  -g -O2
-D_GNU_SOURCE -fcf-protection -mshstk -g0 -c cxx11-ios_failure-lt.s -o
cxx11-ios_failure.lo

cxx11-ios_failure-lt.s contains DWARF5 debug info.  Since -g0 is used,
--gdwarf-5 isn't passed to assembler:

[hjl@gnu-clx-1 gcc]$ ./xgcc -B./ -c /tmp/cxx11-ios_failure-lt.s
/tmp/cxx11-ios_failure-lt.s: Assembler messages:
/tmp/cxx11-ios_failure-lt.s:36733: Error: file number less than one
[hjl@gnu-clx-1 gcc]$ ./xgcc -B./ -c /tmp/cxx11-ios_failure-lt.s -g
[hjl@gnu-clx-1 gcc]$ 

This means that "gcc -c" no longer works on assembly codes generated with
-g when DWARF5 is enabled.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
The assembler patch is posted at

https://sourceware.org/pipermail/binutils/2021-January/114978.html

GCC should emit ".dwarf_level 5" when generating DWARF5 info.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I guess the primary question is why does it emit any .file directives or
.debug_str when it is compiled with -g -O2 -g0.  That seems like the bug.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Ah, no, the *.s file is generated with -g, but the assembler isn't able to cope
with it.
I'd say that the assembler shouldn't require any directive or flag but just
assemble it.
Anything else seems to be an assembler bug.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The assembler has all the information in the assembly, .debug_info section
contains version etc.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I'd be for automatic bumping to dwarf5 level if .file 0 is seen, but remember
that it happened and issue an error if .debug_info with version older than 5 is
seen in the file.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[mark at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #8 from Mark Wielaard <mark at gcc dot gnu.org> ---
I am not sure where the -g -O2 -g0 comes from. I must have missed this in my
testing.

The issue is the .file 0 directive, which is special to gas (only valid with
-gdwarf-5).

It is generated by dwarf2out_finish ():

  /* Output the source line correspondence table.  We must do this
     even if there is no line information.  Otherwise, on an empty
     translation unit, we will generate a present, but empty,
     .debug_info section.  IRIX 6.5 `nm' will then complain when
     examining the file.  This is done late so that any filenames
     used by the debug_info section are marked as 'used'.  */
  switch_to_section (debug_line_section);
  ASM_OUTPUT_LABEL (asm_out_file, debug_line_section_label);
  if (! output_asm_line_debug_info ())
    output_line_info (false);
  else if (asm_outputs_debug_line_str ())
    {
      /* When gas outputs DWARF5 .debug_line[_str] then we have to
         tell it the comp_dir and main file name for the zero entry
         line table.  */
      const char *comp_dir, *filename0;

      comp_dir = comp_dir_string ();
      if (comp_dir == NULL)
        comp_dir = "";

      filename0 = get_AT_string (comp_unit_die (), DW_AT_name);
      if (filename0 == NULL)
        filename0 = "";

      fprintf (asm_out_file, "\t.file 0 ");
      output_quoted_string (asm_out_file, remap_debug_filename (comp_dir));
      fputc (' ', asm_out_file);
      output_quoted_string (asm_out_file, remap_debug_filename (filename0));
      fputc ('\n', asm_out_file);
    }

So it looks like the asm_outputs_debug_line_str () is wrong:

/* Returns TRUE if we are outputting DWARF5 and the assembler supports
   DWARF5 .debug_line tables using .debug_line_str or we generate
   it ourselves, except for split-dwarf which doesn't have a
   .debug_line_str.  */
static bool
asm_outputs_debug_line_str (void)
{
  if (dwarf_version >= 5
      && ! output_asm_line_debug_info ()
      && DWARF5_USE_DEBUG_LINE_STR)
    return true;
  else
    {
#if defined(HAVE_AS_GDWARF_5_DEBUG_FLAG) &&
defined(HAVE_AS_WORKING_DWARF_N_FLAG)
      return !dwarf_split_debug_info && dwarf_version >= 5;
#else
      return false;
#endif
    }
}

It probably should check debug_info_level > DINFO_LEVEL_NONE.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Bootstrap is fine if one uses older binutils.
The thing is that cxx11-ios_failure* is built by hand first with -g -O2 -S,
then the assembly is modified by a script and then it is assembled, and as
older assemblers would fail miserably on assembling .s file containing
.debug_info etc. with -g (-gdwarf-2 passed to assembler), the assembly is
invoked with -g -O2 -c -g0.
I really think this should be fixed solely on the assembler side, and
if needed, we can add a temporary workaround, I guess compiling
cxx11-ios_failure* with -gno-as-loc-support could fix that.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Jakub Jelinek from comment #9)
> Bootstrap is fine if one uses older binutils.
> The thing is that cxx11-ios_failure* is built by hand first with -g -O2 -S,
> then the assembly is modified by a script and then it is assembled, and as
> older assemblers would fail miserably on assembling .s file containing
> .debug_info etc. with -g (-gdwarf-2 passed to assembler), the assembly is
> invoked with -g -O2 -c -g0.
> I really think this should be fixed solely on the assembler side, and
> if needed, we can add a temporary workaround, I guess compiling
> cxx11-ios_failure* with -gno-as-loc-support could fix that.

Assembler option:

 --gdwarf-<N>            generate DWARF<N> debugging information. 2 <= <N> <= 5

both accepts and generates DWARF<N> info.  This decision is made very early.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[mark at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #11 from Mark Wielaard <mark at gcc dot gnu.org> ---
Aha, now I see in libstdc++-v3/src/c++11/Makefile.am:

if ENABLE_DUAL_ABI
# Rewrite the type info for __ios_failure.
rewrite_ios_failure_typeinfo = sed -e
'/^_*_ZTISt13__ios_failure:/,/_ZTVN10__cxxabiv120__si_class_type_infoE/s/_ZTVN10__cxxabiv120__si_class_type_infoE/_ZTVSt19__iosfail_type_info/'

cxx11-ios_failure-lt.s: cxx11-ios_failure.cc
        $(LTCXXCOMPILE) -S $< -o tmp-cxx11-ios_failure-lt.s
        -test -f tmp-cxx11-ios_failure-lt.o && mv -f tmp-cxx11-ios_failure-lt.o
tmp-cxx11-ios_failure-lt.s
        $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
        -rm -f tmp-$@
cxx11-ios_failure.s: cxx11-ios_failure.cc
        $(CXXCOMPILE) -S $< -o tmp-$@
        $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
        -rm -f tmp-$@

cxx11-ios_failure.lo: cxx11-ios_failure-lt.s
        $(LTCXXCOMPILE) -g0 -c $< -o $@
cxx11-ios_failure.o: cxx11-ios_failure.s
        $(CXXCOMPILE) -g0 -c $<
endif

Then my workaround of checking for debug_info_level > DINFO_LEVEL_NONE indeed
wouldn't work. It is explicitly generating debuginfo for the assembly file and
then adding -g0 when turning the assembly file into an object file. So that is
too late.

I don't think adding -gno-as-loc-support to the -S invocation will work because
of the definition of asm_outputs_debug_line_str () which is true if
dwarf_version >= 5 && ! output_asm_line_debug_info () &&
DWARF5_USE_DEBUG_LINE_STR. So then it will still generate the .file 0
directive.

Ideally gas wouldn't error on .file 0, but simply ignore it when not generating
DWARF5.

Maybe the simplest workaround for now would be also adding -g0 to the -S
invocations?

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[mark at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #12 from Mark Wielaard <mark at gcc dot gnu.org> ---
On the binutils gas side it could be as simple as turning the error into a
warning:

diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index a428370ecca..a216bfd6b28 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -1044,7 +1044,7 @@ dwarf2_directive_filename (void)

   if ((offsetT) num < 1 && DWARF2_LINE_VERSION < 5)
     {
-      as_bad (_("file number less than one"));
+      as_warn (_("file number less than one, ignored"));
       ignore_rest_of_line ();
       return NULL;
     }
@@ -1143,7 +1143,8 @@ dwarf2_directive_loc (int dummy ATTRIBUTE_UNUSED)
     {
       if (filenum != 0 || DWARF2_LINE_VERSION < 5)
        {
-         as_bad (_("file number less than one"));
+         as_warn (_("file number less than one, ignored"));
+         ignore_rest_of_line ();
          return;
        }
     }
diff --git a/gas/testsuite/gas/lns/lns-diag-1.l
b/gas/testsuite/gas/lns/lns-diag-1.l
index 1256e85cfcb..d8aa84d9d1a 100644
--- a/gas/testsuite/gas/lns/lns-diag-1.l
+++ b/gas/testsuite/gas/lns/lns-diag-1.l
@@ -1,5 +1,5 @@
 .*: Assembler messages:
-.*:2: Error: file number less than one
+.*:2: Warning: file number less than one, ignored
 .*:3: Error: missing string
 .*:4: Error: file table slot 1 is already occupied.*
 .*:8: Error: unassigned file number 3
@@ -9,7 +9,7 @@
 .*:19: Error: bad or irreducible absolute expression
 .*:23: Error: isa number less than zero
 .*:26: Error: bad or irreducible absolute expression
-.*:26: Error: file number less than one
+.*:26: Warning: file number less than one, ignored
 .*:27: Error: bad or irreducible absolute expression
 .*:28: Error: unknown .loc sub-directive `frobnitz'
 .*:29: Error: unknown .loc sub-directive `frobnitz'

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #13 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
But then it will warn and not do what it was expected to do.

Anyway, I've rebuilt cc1plus (on a box without new binutils) with hacking up
auto-host.h so that it normally emits .file 0 "..." directive, and with
-gno-as-loc-support it doesn't emit it.  Will try it soon in a koji build where
it failed.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 49986
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49986&action=edit
A patch

How about this assembler patch?

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Comment on attachment 49986
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49986
A patch

If that works, that would be great.
I can't easily test it right away, but perhaps you could.
Just compile some other libstdc++ source with -g -O2 -c
on gcc configured against latest binutils, save the *.o file and repeat
with -g -O2 -S + assembly by hand without -g* and compare if the readelf -wl
between the two is identical.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
And the temporary workaround could be
--- libstdc++-v3/src/c++11/Makefile.am.jj       2021-01-04 10:26:02.067970728
+0100
+++ libstdc++-v3/src/c++11/Makefile.am  2021-01-17 17:20:58.580262364 +0100
@@ -141,12 +141,12 @@ if ENABLE_DUAL_ABI
 rewrite_ios_failure_typeinfo = sed -e
'/^_*_ZTISt13__ios_failure:/,/_ZTVN10__cxxabiv120__si_class_type_infoE/s/_ZTVN10__cxxabiv120__si_class_type_infoE/_ZTVSt19__iosfail_type_info/'

 cxx11-ios_failure-lt.s: cxx11-ios_failure.cc
-       $(LTCXXCOMPILE) -S $< -o tmp-cxx11-ios_failure-lt.s
+       $(LTCXXCOMPILE) -gno-as-loc-support -S $< -o tmp-cxx11-ios_failure-lt.s
        -test -f tmp-cxx11-ios_failure-lt.o && mv -f tmp-cxx11-ios_failure-lt.o
tmp-cxx11-ios_failure-lt.s
        $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
        -rm -f tmp-$@
 cxx11-ios_failure.s: cxx11-ios_failure.cc
-       $(CXXCOMPILE) -S $< -o tmp-$@
+       $(CXXCOMPILE) -gno-as-loc-support -S $< -o tmp-$@
        $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
        -rm -f tmp-$@

--- libstdc++-v3/src/c++11/Makefile.in.jj       2020-12-17 02:29:28.734557483
+0100
+++ libstdc++-v3/src/c++11/Makefile.in  2021-01-17 17:21:27.510931383 +0100
@@ -852,12 +852,12 @@ limits.o: limits.cc
        $(CXXCOMPILE) -fchar8_t -c $<

 @ENABLE_DUAL_ABI_TRUE@cxx11-ios_failure-lt.s: cxx11-ios_failure.cc
-@ENABLE_DUAL_ABI_TRUE@ $(LTCXXCOMPILE) -S $< -o tmp-cxx11-ios_failure-lt.s
+@ENABLE_DUAL_ABI_TRUE@ $(LTCXXCOMPILE) -gno-as-loc-support -S $< -o
tmp-cxx11-ios_failure-lt.s
 @ENABLE_DUAL_ABI_TRUE@ -test -f tmp-cxx11-ios_failure-lt.o && mv -f
tmp-cxx11-ios_failure-lt.o tmp-cxx11-ios_failure-lt.s
 @ENABLE_DUAL_ABI_TRUE@ $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
 @ENABLE_DUAL_ABI_TRUE@ -rm -f tmp-$@
 @ENABLE_DUAL_ABI_TRUE@cxx11-ios_failure.s: cxx11-ios_failure.cc
-@ENABLE_DUAL_ABI_TRUE@ $(CXXCOMPILE) -S $< -o tmp-$@
+@ENABLE_DUAL_ABI_TRUE@ $(CXXCOMPILE) -gno-as-loc-support -S $< -o tmp-$@
 @ENABLE_DUAL_ABI_TRUE@ $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
 @ENABLE_DUAL_ABI_TRUE@ -rm -f tmp-$@

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

--- Comment #17 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:2e43880dbd4cb9722ae99708c01c399f985dc7c3

commit r11-6765-g2e43880dbd4cb9722ae99708c01c399f985dc7c3
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Jan 18 11:28:17 2021 +0100

    libstd++: : Add workaround for as Error: file number less than one error
[PR98708]

    As mentioned in the PR, since the switch to DWARF5 by default instead of
    DWARF4, gcc fails to build when configured against recent binutils.

    The problem is that cxx11-ios_failure* is built in separate steps,
    -S compilation (with -g -O2) followed by some sed and followed by
    -c -g -O2 -g0 assembly.  When gcc is configured against recent binutils
    and DWARF5 is the default, we emit .file 0 "..." directive on which the
    assembler then fails (unless --gdwarf-5 is passed to it, but we don't want
    that generally because on the other side older assemblers don't like -g*
    passed to it when invoked on *.s file with compiler generated debug info.

    I hope the bug will be fixed soon on the binutils side, but it would be
nice
    to have a workaround.

    The following patch is one of the possibilities, another one is to do that
    but add configure check for whether it is needed,
    essentially
    echo 'int main () { return 0; }' > conftest.c
    ${CXX} ${CXXFLAGS} -g -O2 -S conftest.c -o conftest.s
    ${CXX} ${CXXFLAGS} -g -O2 -g0 -c conftest.s -o conftest.o
    and if the last command fails, we need that -gno-as-loc-support.
    Or yet another option would be I think do a different check, whether
    ${CXX} ${CXXFLAGS} -g -O2 -S conftest.c -o conftest.s
    ${CXX} ${CXXFLAGS} -g -O2 -c conftest.s -o conftest.o
    works and if yes, don't add the -g0 to cxx11-ios_failure*.s assembly.

    2021-01-18  Jakub Jelinek  <jakub@redhat.com>

            PR debug/98708
            * src/c++11/Makefile.am (cxx11-ios_failure-lt.s,
cxx11-ios_failure.s):
            Compile with -gno-as-loc-support.
            * src/c++11/Makefile.in: Regenerated.

[Bug debug/98708] [11 Regression] cxx11-ios_failure-lt.s:36733: Error: file number less than one by r11-6755

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98708

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #18 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Worked around on the gcc side and fixed on the binutils side.