[Bug debug/125862] New: btf_decl_taf ignored for types

[vineetg at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125862

            Bug ID: 125862
           Summary: btf_decl_taf ignored for types
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vineetg at gcc dot gnu.org
                CC: dfaust at gcc dot gnu.org, jemarch at gcc dot gnu.org
  Target Milestone: ---

Yonghong reported that gcc doesn't support the btf_decl_tag for types [1]. This
was when reviewing the pahole/kernel changes for enabling the decl tags in
kernel.

[1] https://lore.kernel.org/all/9152fde6-d35c-4688-9ff1-c7fe152c9b2a@linux.dev/

/* tag on a typedef */
typedef struct foo foo_t1 __tag("typedef_foo_tag");
typedef struct {int foo2;} foo_t2 __tag("typedef_foo2_tag");

$ /home/yhs/work/gcc-build/opt/gcc-16.1/bin/gcc -O2 -gbtf -g -c decl_tag.c -o
decl_tag.o
decl_tag.c:30:1: warning: ‘btf_decl_tag’ attribute does not apply to types
[-Wattributes]
    30 | } __tag("struct_foo_tag");
       | ^