Hi! As mentioned in the PR and reproduced on the testcase, we ICE during LTO streaming because C++ annotation arguments can contain trees LTO streaming doesn't handle. We don't really need annotations when the FE is done with the whole TU, annotations are always TU local and not exposed to the rest and used in consteval only stuff, so the following patch just removes all annotations at free-lang-data time.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2026-01-28 Jakub Jelinek <[email protected]> PR c++/123837 * ipa-free-lang-data.cc (find_decls_types_r): Remove C++ annotations from {DECL,TYPE}_ATRIBUTES. * g++.dg/reflect/annotations9.C: New test. --- gcc/ipa-free-lang-data.cc.jj 2026-01-12 09:58:18.735429290 +0100 +++ gcc/ipa-free-lang-data.cc 2026-01-27 19:24:15.046503575 +0100 @@ -730,6 +730,10 @@ find_decls_types_r (tree *tp, int *ws, v if (TREE_CODE (t) != TYPE_DECL) fld_worklist_push (DECL_INITIAL (t), fld); + /* Remove C++ annotations, those aren't needed for LTO and contain + trees we sometimes can't stream. */ + DECL_ATTRIBUTES (t) + = remove_attribute ("annotation ", DECL_ATTRIBUTES (t)); fld_worklist_push (DECL_ATTRIBUTES (t), fld); fld_worklist_push (DECL_ABSTRACT_ORIGIN (t), fld); @@ -763,6 +767,10 @@ find_decls_types_r (tree *tp, int *ws, v fld_worklist_push (TYPE_CACHED_VALUES (t), fld); fld_worklist_push (TYPE_SIZE (t), fld); fld_worklist_push (TYPE_SIZE_UNIT (t), fld); + /* Remove C++ annotations, those aren't needed for LTO and contain + trees we sometimes can't stream. */ + TYPE_ATTRIBUTES (t) + = remove_attribute ("annotation ", TYPE_ATTRIBUTES (t)); fld_worklist_push (TYPE_ATTRIBUTES (t), fld); fld_worklist_push (TYPE_POINTER_TO (t), fld); fld_worklist_push (TYPE_REFERENCE_TO (t), fld); --- gcc/testsuite/g++.dg/reflect/annotations9.C.jj 2026-01-27 19:32:44.626859348 +0100 +++ gcc/testsuite/g++.dg/reflect/annotations9.C 2026-01-27 19:32:14.907363491 +0100 @@ -0,0 +1,14 @@ +// PR c++/123837 +// { dg-do compile { target c++26 } } +// { dg-additional-options "-freflection" } +// { dg-additional-options "-flto" { target lto } } + +struct A {}; +[[=A {}]] int a {}; +struct [[=A {}]] B { int b; }; +B b {}; + +int +main () +{ +} Jakub
