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.
