https://gcc.gnu.org/g:5f9f8711bf791130fd30bc1f04b2097f3ef25f0b
commit r17-4859-g5f9f8711bf791130fd30bc1f04b2097f3ef25f0b Author: Marek Polacek <[email protected]> Date: Wed Sep 30 14:02:21 2026 -0400 c++: ICE with -Wsubobject-linkage and function type [PR127672] Here we crash in decl_namespace_context because function types (or pointer-to-data-member types) like void() have no TYPE_MAIN_DECL: decl = CP_DECL_CONTEXT (TYPE_MAIN_DECL (decl)); We got there from the constrain_class_visibility TYPE_FIELDS walk which emits the -Wsubobject-linkage warning. And this test has: namespace { struct P { }; } struct S { void (*f) (P *); }; I'm using OVERLOAD_TYPE_P, inspired by min_vis_r. PR c++/127672 gcc/cp/ChangeLog: * decl2.cc (constrain_class_visibility): Check OVERLOAD_TYPE_P before calling decl_anon_ns_mem_p. gcc/testsuite/ChangeLog: * g++.dg/warn/Wsubobject-linkage-6.C: New test. Reviewed-by: Jason Merrill <[email protected]> Diff: --- gcc/cp/decl2.cc | 1 + gcc/testsuite/g++.dg/warn/Wsubobject-linkage-6.C | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc index 7fe567f98db1..563fae5db0d4 100644 --- a/gcc/cp/decl2.cc +++ b/gcc/cp/decl2.cc @@ -3598,6 +3598,7 @@ constrain_class_visibility (tree type) type, t, nlt); } else if (cxx_dialect > cxx98 + && OVERLOAD_TYPE_P (ftype) && !decl_anon_ns_mem_p (ftype)) warning (OPT_Wsubobject_linkage, "\ %qT has a field %q#D whose type has internal linkage", diff --git a/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-6.C b/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-6.C new file mode 100644 index 000000000000..ea77f14386fe --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wsubobject-linkage-6.C @@ -0,0 +1,10 @@ +// PR c++/127672 +// { dg-do compile { target c++11 } } + +namespace { struct P { }; } + +#line 7 "foo.C" +struct S { void (*f) (P *); }; // { dg-warning "uses the anonymous namespace" } +struct S2 { void (P::*m) (); }; // { dg-warning "uses the anonymous namespace" } +struct S3 { P (*g) (); }; // { dg-warning "uses the anonymous namespace" } +struct S4 { int P::*d; }; // { dg-warning "uses the anonymous namespace" }
