https://gcc.gnu.org/g:acfe19f03bccd1f3183fd5d70d7a3c8c85e62fac
commit r15-9187-gacfe19f03bccd1f3183fd5d70d7a3c8c85e62fac
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Apr 1 19:22:18 2025 -0400
c++/modules: inline loaded at eof
std/format/string.cc and a few other libstdc++ tests were failing with
module std with undefined references to __failed_to_parse_format_spec. This
turned out to be because since r15-8012 we don't end up calling
note_vague_linkage_fn for functions loaded after at_eof is set.
But once import_export_decl decides on COMDAT linkage, we should be able to
just clear DECL_EXTERNAL and let cgraph take it from there.
I initially made this change in import_export_decl, but decided that for GCC
15 it would be safer to limit the change to modules. For GCC 16 I'd like to
do away with DECL_NOT_REALLY_EXTERN entirely, it's been obsolete since
cgraphunit in 2003.
gcc/cp/ChangeLog:
* module.cc (module_state::read_cluster)
(post_load_processing): Clear DECL_EXTERNAL if DECL_COMDAT.
Diff:
---
gcc/cp/module.cc | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index ce22b2ece3f0..89deabbfee37 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -16679,6 +16679,15 @@ module_state::read_cluster (unsigned snum)
#endif
cfun->returns_struct = aggr;
expand_or_defer_fn (decl);
+
+ /* If we first see this function after at_eof, it doesn't get
+ note_vague_linkage_fn from tentative_decl_linkage, so the loop in
+ c_parse_final_cleanups won't consider it. But with DECL_COMDAT we
+ can just clear DECL_EXTERNAL and let cgraph decide.
+ FIXME handle this outside module.cc after GCC 15. */
+ if (at_eof && DECL_COMDAT (decl) && DECL_EXTERNAL (decl)
+ && DECL_NOT_REALLY_EXTERN (decl))
+ DECL_EXTERNAL (decl) = false;
}
}
@@ -19159,6 +19168,10 @@ post_load_processing ()
gcc_checking_assert (DECL_MAYBE_IN_CHARGE_CDTOR_P (decl));
expand_or_defer_fn (decl);
+ /* As in module_state::read_cluster. */
+ if (at_eof && DECL_COMDAT (decl) && DECL_EXTERNAL (decl)
+ && DECL_NOT_REALLY_EXTERN (decl))
+ DECL_EXTERNAL (decl) = false;
}
cfun = old_cfun;
