Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
OK for trunk/16?
-- >8 --
Here the nonsensical constraint-expression f() == 42 isn't getting
rejected ahead of time ultimately because we pass no_toplevel_fold_p=true
to cp_parser_binary_expression which makes it use build_min instead of
build_x_binary_op to avoid undesirable folding/canonicalization for sake
of OpenMP for loop parsing (r145014). But this certainly doesn't happen
during templated parsing, and constraint-expressions are always
templated, so we might as well pass no_toplevel_fold_p=false here.
PR c++/125490
gcc/cp/ChangeLog:
* parser.cc (cp_parser_constraint_expression): Pass
no_toplevel_fold_p=false instead of =true to
cp_parser_binary_expression.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-pr125490.C: New test.
---
gcc/cp/parser.cc | 2 +-
gcc/testsuite/g++.dg/cpp2a/concepts-pr125490.C | 10 ++++++++++
2 files changed, 11 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr125490.C
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index b5c8c62118cc..c1797191b833 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -34761,7 +34761,7 @@ cp_parser_constraint_expression (cp_parser *parser)
{
processing_constraint_expression_sentinel parsing_constraint;
++processing_template_decl;
- cp_expr expr = cp_parser_binary_expression (parser, false, true,
+ cp_expr expr = cp_parser_binary_expression (parser, false, false,
PREC_NOT_OPERATOR, NULL);
--processing_template_decl;
if (check_for_bare_parameter_packs (expr))
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr125490.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-pr125490.C
new file mode 100644
index 000000000000..a33416b232d1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr125490.C
@@ -0,0 +1,10 @@
+// PR c++/125490
+// { dg-do compile { target c++20 } }
+
+void f();
+
+template<class T>
+concept C = f() == 42; // { dg-error "invalid operands" }
+
+template<class T>
+concept D = requires { requires f() == 42; }; // { dg-error "invalid operands"
}
--
2.54.0.rc1.54.g60f07c4f5c
