On 7/26/26 7:16 PM, Odysseas Georgoudis wrote:
This fixes PR c++/124983 by postponing access checks for dependent
declarations until substitution, avoiding the ICE during typo correction.
- /* A dependent USING_DECL will be checked after tsubsting. */
+ /* A dependent declaration will be checked after tsubsting. */
if (TREE_CODE (decl) != USING_DECL
+ && !uses_template_parms (decl)
I was concerned that this was too broad, as we should still be able to
check access for members with dependent type. Though I suppose it
doesn't actually matter much because any such members will be
accessible, so we never hit the assert.
But it still seems preferable to combine these checks to focus on the
problematic case where the scope is still dependent. So I'm pushing the
attached. Thanks!
Jason
From 4bc54be0a6cc30440dbab560cdaa9436ed8860ca Mon Sep 17 00:00:00 2001
From: Odysseas Georgoudis <[email protected]>
Date: Sun, 26 Jul 2026 23:48:20 +0100
Subject: [PATCH] c++: Avoid access check for dependent lookup result
[PR124983]
To: [email protected]
strip_using_decl turns a dependent typename USING_DECL into a dependent
TYPE_DECL. If member lookup finds that declaration while looking for a
typo correction, lookup_member can therefore try to perform an access
check on it. Access checks for dependent declarations need to wait until
substitution, and enforce_access asserts this invariant.
Skip the access check whenever the lookup result refers to a member of a
dependent scope, not just when it remains a USING_DECL.
gcc/cp/ChangeLog:
PR c++/124983
* search.cc (lookup_member): Skip access checks for declarations
from dependent scope.
gcc/testsuite/ChangeLog:
PR c++/124983
* g++.dg/template/pr124983.C: New test.
Signed-off-by: Odysseas Georgoudis <[email protected]>
Co-authored-by: Jason Merrill <[email protected]>
---
gcc/cp/search.cc | 7 ++--
gcc/testsuite/g++.dg/template/pr124983.C | 49 ++++++++++++++++++++++++
2 files changed, 53 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/template/pr124983.C
diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index a51fd1cd6a7..9845032d28d 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -1280,9 +1280,10 @@ lookup_member (tree xbasetype, tree name, int protect, bool want_type,
{
tree decl = is_overloaded_fn (rval) ? get_first_fn (rval) : rval;
decl = strip_using_decl (decl);
- /* A dependent USING_DECL will be checked after tsubsting. */
- if (TREE_CODE (decl) != USING_DECL
- && !DECL_IOBJ_MEMBER_FUNCTION_P (decl)
+ /* A dependent declaration will be checked after tsubsting. */
+ if (!dependent_scope_p (DECL_CONTEXT (decl))
+ && !(DECL_DECLARES_FUNCTION_P (decl)
+ && DECL_IOBJ_MEMBER_FUNCTION_P (decl))
&& !perform_or_defer_access_check (basetype_path, decl, decl,
complain, afi))
return error_mark_node;
diff --git a/gcc/testsuite/g++.dg/template/pr124983.C b/gcc/testsuite/g++.dg/template/pr124983.C
new file mode 100644
index 00000000000..72819af48c0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/pr124983.C
@@ -0,0 +1,49 @@
+// PR c++/124983
+// { dg-do compile }
+
+template <class T>
+struct A
+{
+ using typename T::Type;
+
+ void f()
+ {
+ this->type(); // { dg-error "no member named 'type'; did you mean 'Type'" }
+ }
+};
+
+template <class T>
+struct B
+{
+ typedef typename T::Type Type;
+ static T Value;
+
+ void f()
+ {
+ this->type(); // { dg-error "no member named 'type'; did you mean 'Type'" }
+ this->value(); // { dg-error "no member named 'value'; did you mean 'Value'" }
+ }
+};
+
+struct X
+{
+ typedef int Type;
+};
+
+template <class T>
+struct C
+{
+private:
+ typedef typename T::Type Type; // { dg-message "declared private" }
+ static T Value; // { dg-message "declared private" }
+};
+
+template <class T>
+void g()
+{
+ typename C<T>::Type t; // { dg-error "private within this context" }
+ (void) C<T>::Value; // { dg-error "private within this context" }
+ (void) t;
+}
+
+template void g<X>(); // { dg-message "required from here" }
--
2.55.0
