From f645da0e4ab9438dfd0c047c710c7ec6a7d6d8f3 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Thu, 21 Jan 2021 14:04:55 -0500 Subject: [PATCH] c++: Fix excessive instantiation inside decltype [PR71879] Here after resolving the address of a template-id inside decltype, we end up instantiating the chosen specialization (from the call to mark_used in resolve_nondeduced_context), even though only its type is needed. This patch sets cp_unevaluated_operand throughout finish_decltype_type, so that in particular it's set during the call to resolve_nondeduced_context within. gcc/cp/ChangeLog: PR c++/71879 * semantics.c (finish_decltype_type): Set up a cp_unevaluated sentinel at the start of the function. Remove a now-redundant manual adjustment of cp_unevaluated_operand. gcc/testsuite/ChangeLog: PR c++/71879 * g++.dg/cpp0x/decltype-71879.C: New test. --- gcc/cp/semantics.c | 5 +++-- gcc/testsuite/g++.dg/cpp0x/decltype-71879.C | 5 +++++ 2 files changed, 8 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/decltype-71879.C diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 244fc70d02d..067095276af 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -10080,6 +10080,9 @@ finish_decltype_type (tree expr, bool id_expression_or_member_access_p, return error_mark_node; } + /* decltype is an unevaluated context. */ + cp_unevaluated u; + /* Depending on the resolution of DR 1172, we may later need to distinguish instantiation-dependent but not type-dependent expressions so that, say, A::U doesn't require 'typename'. */ @@ -10095,9 +10098,7 @@ finish_decltype_type (tree expr, bool id_expression_or_member_access_p, } else if (processing_template_decl) { - ++cp_unevaluated_operand; expr = instantiate_non_dependent_expr_sfinae (expr, complain); - --cp_unevaluated_operand; if (expr == error_mark_node) return error_mark_node; } diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype-71879.C b/gcc/testsuite/g++.dg/cpp0x/decltype-71879.C new file mode 100644 index 00000000000..9da4d40ca70 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/decltype-71879.C @@ -0,0 +1,5 @@ +// PR c++/71879 +// { dg-do compile { target c++11 } } + +template void f(T x) { x.fail(); } +using R = decltype(&f); -- 2.30.2