According to [temp.concept]/6 and [temp.pre]/9, a concept definition and
a requires clause are both unevaluated contexts, and hence satisfaction
deals only with unevaluated operands, so we should set cp_unevaluated
in these three situations.
(I guess we should set cp_unevaluated during normalization too, but I
wasn't able to construct a testcase for which it makes a difference.)
Bootstrapped and regtested on x86_64-pc-linux-gnu, and also tested on
cmcstl2 and range-v3, does this look OK for trunk?
gcc/cp/ChangeLog:
PR c++/99961
* constraint.cc (satisfy_normalized_constraints): Set
cp_unevaluated.
* parser.c (cp_parser_concept_definition): Likewise.
(cp_parser_requires_clause_opt): Likewise.
gcc/testsuite/ChangeLog:
PR c++/99961
* g++.dg/cpp2a/concepts-uneval1.C: New test.
---
gcc/cp/constraint.cc | 3 +++
gcc/cp/parser.c | 6 ++++++
gcc/testsuite/g++.dg/cpp2a/concepts-uneval1.C | 10 ++++++++++
3 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-uneval1.C
diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 0ddb2990dd9..6c8e29d809f 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3066,6 +3066,9 @@ satisfy_normalized_constraints (tree t, tree args,
sat_info info)
/* We need to check access during satisfaction. */
deferring_access_check_sentinel acs (dk_no_deferred);
+ /* Constraints are an unevaluated operands. */
+ cp_unevaluated u;
+
return satisfy_constraint_r (t, args, info);
}
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index b6f94bdda23..8b7801b2be7 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -28353,6 +28353,9 @@ cp_parser_label_declaration (cp_parser* parser)
static tree
cp_parser_concept_definition (cp_parser *parser)
{
+ /* A concept definition is an unevaluated context. */
+ cp_unevaluated u;
+
gcc_assert (cp_lexer_next_token_is_keyword (parser->lexer, RID_CONCEPT));
cp_lexer_consume_token (parser->lexer);
@@ -28714,6 +28717,9 @@ cp_parser_constraint_expression (cp_parser *parser)
static tree
cp_parser_requires_clause_opt (cp_parser *parser, bool lambda_p)
{
+ /* A requires clause is an unevaluated context. */
+ cp_unevaluated u;
+
cp_token *tok = cp_lexer_peek_token (parser->lexer);
if (tok->keyword != RID_REQUIRES)
{
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-uneval1.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-uneval1.C
new file mode 100644
index 00000000000..4c5f1b5c019
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-uneval1.C
@@ -0,0 +1,10 @@
+// PR c++/99961
+// { dg-do compile { target c++20 } }
+
+struct A { static const int x = 42; bool y; };
+
+void f(auto a) requires (a.x == 42) { }
+template void f(A);
+
+template <bool V> concept C = V || A::y;
+static_assert(C<true>);
--
2.31.1.272.g89b43f80a5
