This is a bit complex. Looking up c<T> in the definition of D::c finds
C::c, OK. Looking up c in the definition of E finds D::c, OK. Since the
alias is not dependent, we strip it from the template argument, leaving
using E = A<decltype(c<T>())>;
where 'c' still refers to C::c. But instantiating E looks up 'c' again and
finds D::c, which isn't a function, and sadness ensues.
I think the bug here is looking up 'c' in D at instantiation time; the
declaration we found before is not dependent. This seems to happen because
baselink_for_fns gets BASELINK_BINFO wrong; it is supposed to be the base
where lookup found the functions, C in this case.
Tested x86_64-pc-linux-gnu, applying to trunk.
gcc/cp/ChangeLog:
PR c++/91706
* semantics.c (baselink_for_fns): Fix BASELINK_BINFO.
gcc/testsuite/ChangeLog:
PR c++/91706
* g++.dg/template/lookup17.C: New test.
---
gcc/cp/semantics.c | 6 ++++--
gcc/testsuite/g++.dg/template/lookup17.C | 18 ++++++++++++++++++
2 files changed, 22 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/template/lookup17.C
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index d08c1ddabf9..f506a239864 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -3663,8 +3663,10 @@ baselink_for_fns (tree fns)
cl = currently_open_derived_class (scope);
if (!cl)
cl = scope;
- cl = TYPE_BINFO (cl);
- return build_baselink (cl, cl, fns, /*optype=*/NULL_TREE);
+ tree access_path = TYPE_BINFO (cl);
+ tree conv_path = (cl == scope ? access_path
+ : lookup_base (cl, scope, ba_any, NULL, tf_none));
+ return build_baselink (conv_path, access_path, fns, /*optype=*/NULL_TREE);
}
/* Returns true iff DECL is a variable from a function outside
diff --git a/gcc/testsuite/g++.dg/template/lookup17.C
b/gcc/testsuite/g++.dg/template/lookup17.C
new file mode 100644
index 00000000000..b8571b9f1eb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/lookup17.C
@@ -0,0 +1,18 @@
+// PR c++/91706
+// { dg-do compile { target c++11 } }
+// { dg-additional-options -g }
+
+template <bool> struct A;
+
+struct B { static constexpr bool g = false; };
+
+struct C {
+ template <typename> static B c ();
+};
+
+template <class T> struct D : C {
+ using c = decltype (c<T>());
+ using E = A<c::g>;
+};
+
+D<int> g;
base-commit: 715614ec3ec5390293e508bb190335d28db1fa8b
--
2.27.0
