On 4/11/21 11:37 AM, Patrick Palka wrote:
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. */
OK fixing the grammar of this sentence.
+ cp_unevaluated u; + return satisfy_constraint_r (t, args, info); }diff --git a/gcc/cp/parser.c b/gcc/cp/parser.cindex 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>);
