From f931bd7725f5cea948dd55ac370b5b9fd9a00198 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Fri, 9 Feb 2024 12:40:28 -0500 Subject: c++/modules: anon union member of as-base class [PR112580] Here when streaming in the fields of the as-base version of _Formatting_scanner we end up overwriting ANON_AGGR_TYPE_FIELD of the anonymous union type, since it turns out this type is shared between the original FIELD_DECL and the as-base FIELD_DECL copy (copied during layout_class_type). ANON_AGGR_TYPE_FIELD first gets properly set to the original FIELD_DECL when streaming in the canonical definition of _Formatting_scanner, and then gets overwritten to the as-base FIELD_DECL when streaming in the the as-base definition. This leads to lookup_anon_field later giving the wrong answer when resolving the _M_values use at instantiation time. This patch makes us avoid overwriting ANON_AGGR_TYPE_FIELD when streaming in an as-base class definition; it should already be properly set at that point. PR c++/112580 gcc/cp/ChangeLog: * module.cc (trees_in::read_class_def): When streaming in an anonymous union field of an as-base class, don't overwrite ANON_AGGR_TYPE_FIELD. gcc/testsuite/ChangeLog: * g++.dg/modules/anon-3_a.H: New test. * g++.dg/modules/anon-3_b.C: New test. Reviewed-by: Jason Merrill --- gcc/cp/module.cc | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'gcc/cp/module.cc') diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc index 3c2fef0e..560d8f3 100644 --- a/gcc/cp/module.cc +++ b/gcc/cp/module.cc @@ -12178,8 +12178,16 @@ trees_in::read_class_def (tree defn, tree maybe_template) if (TREE_CODE (decl) == FIELD_DECL && ANON_AGGR_TYPE_P (TREE_TYPE (decl))) - ANON_AGGR_TYPE_FIELD - (TYPE_MAIN_VARIANT (TREE_TYPE (decl))) = decl; + { + tree anon_type = TYPE_MAIN_VARIANT (TREE_TYPE (decl)); + if (DECL_NAME (defn) == as_base_identifier) + /* ANON_AGGR_TYPE_FIELD should already point to the + original FIELD_DECL; don't overwrite it to point + to the as-base FIELD_DECL copy. */ + gcc_checking_assert (ANON_AGGR_TYPE_FIELD (anon_type)); + else + ANON_AGGR_TYPE_FIELD (anon_type) = decl; + } if (TREE_CODE (decl) == USING_DECL && TREE_CODE (USING_DECL_SCOPE (decl)) == RECORD_TYPE) -- cgit v1.1