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* [gcc r13-806] c++: lambda in concept [PR105652]
@ 2022-05-28 3:44 Jason Merrill
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From: Jason Merrill @ 2022-05-28 3:44 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:221acd67ca50f8f069037e034a3250f13d75a9f5
commit r13-806-g221acd67ca50f8f069037e034a3250f13d75a9f5
Author: Jason Merrill <jason@redhat.com>
Date: Thu May 26 22:43:05 2022 -0400
c++: lambda in concept [PR105652]
We currently check satisfaction in the context of the constrained
declaration (which may be wrong, see PR104111). When checking C<int>
for S<int>, we currently substitute into the lambda in the context of
S<T> (rather than S<int>, which seems wrong if the above isn't wrong), so
the new closure type thinks its context is S<T>, which confuses debug
output. For the moment, let's work around all of this by overriding the
context of the closure.
PR c++/105652
gcc/cp/ChangeLog:
* pt.cc (tsubst_lambda_expr): Don't let a namespace-scope lambda
instantiate into a class-scope lambda.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-lambda20.C: New test.
Diff:
---
gcc/cp/pt.cc | 17 ++++++++++++-----
gcc/testsuite/g++.dg/cpp2a/concepts-lambda20.C | 17 +++++++++++++++++
2 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 24bbe2f4060..f1f080531a6 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -19740,11 +19740,18 @@ tsubst_lambda_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
return error_mark_node;
if (LAMBDA_EXPR_EXTRA_SCOPE (t) == NULL_TREE)
- /* A lambda in a default argument outside a class gets no
- LAMBDA_EXPR_EXTRA_SCOPE, as specified by the ABI. But
- tsubst_default_argument calls start_lambda_scope, so we need to
- specifically ignore it here, and use the global scope. */
- record_null_lambda_scope (r);
+ {
+ /* A lambda in a default argument outside a class gets no
+ LAMBDA_EXPR_EXTRA_SCOPE, as specified by the ABI. But
+ tsubst_default_argument calls start_lambda_scope, so we need to
+ specifically ignore it here, and use the global scope. */
+ record_null_lambda_scope (r);
+
+ /* If we're pushed into another scope (PR105652), fix it. */
+ if (TYPE_NAMESPACE_SCOPE_P (TREE_TYPE (t)))
+ TYPE_CONTEXT (type) = DECL_CONTEXT (TYPE_NAME (type))
+ = TYPE_CONTEXT (TREE_TYPE (t));
+ }
else
record_lambda_scope (r);
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda20.C b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda20.C
new file mode 100644
index 00000000000..40e5973176e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda20.C
@@ -0,0 +1,17 @@
+// PR c++/105652
+// { dg-do compile { target c++20 } }
+// { dg-additional-options -g }
+
+template<int>
+struct I {};
+
+template<class T>
+concept C = []<int N>(I<N>) { return true; } (I<0>{});
+
+template<class T>
+struct S { };
+
+template<C T>
+struct S<T> { constexpr static bool value = true; };
+
+static_assert(S<int>::value);
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