From 2168bfb81448ae1bfa4351760a23d4ec051c2a00 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Thu, 24 Jun 2021 17:32:02 -0400 Subject: c++: constexpr aggr init of empty class [PR101040] This is basically the aggregate initializer version of PR97566; as in that bug, we are trying to initialize empty field 'obj' in 'single' when there's no CONSTRUCTOR entry for the 'single' base class subobject of 'derived'. As with that bug, the fix is to stop trying to add entries for empty fields, this time in cxx_eval_bare_aggregate. The change to the other function isn't necessary for this version of the patch, but seems worthwhile for robustness anyway. PR c++/101040 PR c++/97566 gcc/cp/ChangeLog: * class.c (is_empty_field): Handle null argument. * constexpr.c (cxx_eval_bare_aggregate): Discard initializer for empty field. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/no_unique_address13.C: New test. --- gcc/cp/constexpr.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'gcc/cp/constexpr.c') diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index a26aead..4cd9db3 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -4449,7 +4449,12 @@ cxx_eval_bare_aggregate (const constexpr_ctx *ctx, tree t, FOR_EACH_CONSTRUCTOR_ELT (v, i, index, value) { tree orig_value = value; - init_subob_ctx (ctx, new_ctx, index, value); + /* Like in cxx_eval_store_expression, omit entries for empty fields. */ + bool no_slot = TREE_CODE (type) == RECORD_TYPE && is_empty_field (index); + if (no_slot) + new_ctx = *ctx; + else + init_subob_ctx (ctx, new_ctx, index, value); int pos_hint = -1; if (new_ctx.ctor != ctx->ctor) { @@ -4495,6 +4500,8 @@ cxx_eval_bare_aggregate (const constexpr_ctx *ctx, tree t, gcc_assert (is_empty_class (TREE_TYPE (TREE_TYPE (index)))); changed = true; } + else if (no_slot) + changed = true; else { if (TREE_CODE (type) == UNION_TYPE -- cgit v1.1