https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120571
--- Comment #2 from Ben Woodard <woodard at redhat dot com> ---
Yes a partial workaround could be something like:
gcc -g -fno-eliminate-unused-debug-types -include impl.h -xc /dev/null -c -o
FOO.o
which will emit the type and the variable but still doesn't give us the
declaration coordinates of the function prototypes. (2 of the 3 things that I
need)
Contents of the .debug_info section:
Compilation Unit @ offset 0:
Length: 0x2c (32-bit)
Version: 5
Unit Type: DW_UT_compile (1)
Abbrev Offset: 0
Pointer Size: 8
<0><c>: Abbrev Number: 1 (DW_TAG_compile_unit)
<d> DW_AT_producer : (indirect string, offset: 0xd): GNU C17 14.2.1
20250110 (Red Hat 14.2.1-7) -mtune=generic -march=x86-64-v3 -g
-fno-eliminate-unused-debug-types
<11> DW_AT_language : 29 (C11)
<12> DW_AT_name : (indirect line string, offset: 0x17): /dev/null
<16> DW_AT_comp_dir : (indirect line string, offset: 0):
/home/ben/Work/abidiff
<1a> DW_AT_stmt_list : 0
<1><1e>: Abbrev Number: 2 (DW_TAG_structure_type)
<1f> DW_AT_name : (indirect string, offset: 0): Point
<23> DW_AT_declaration : 1
<1><23>: Abbrev Number: 3 (DW_TAG_variable)
<24> DW_AT_name : (indirect string, offset: 0x6): ORIGIN
<28> DW_AT_decl_file : 1
<29> DW_AT_decl_line : 4
<2a> DW_AT_decl_column : 21
<2b> DW_AT_type : <0x1e>
<2f> DW_AT_external : 1
<2f> DW_AT_declaration : 1
<1><2f>: Abbrev Number: 0
-fno-eliminate-unused-debug-symbols still doesn't emit the function declaration
coordinates. The output is the same as above. If there was an option like:
-gno-eliminate-function-prototypes
Then we probably would have everything we need.
I didn't see anything like that when scrolling through the -f and the -g
options in the invoking GCC option index page but there are a huge number of
options and I could have missed something.
As for being wasteful, it certainly doesn't need to be the default. We are
completely fine having this behavior turned on only under the control of a
command line argument. Some suggestions are:
Add -gno-eliminate-function-prototypes
extending -fno-eliminate-unused-debug-symbols so that it also includes function
prototypes
Add -gincomplete-declarations or -gno-eliminate-incomplete-declarations (which
would basically be the same as -fno-eliminate-unused-debug-types and either an
extended -fno-eliminate-unused-debug-symbols or something like
-gno-eliminate-function-prototypes
or add it to -g3 which is users kind of understand as "give me everything
you've got, I don't care how big the .debug_info" section ends up being."
