Here, the problem ultimately seems to be that tsubst_copy_and_build,
when called with empty args as we do during non-dependent expression
folding, doesn't touch BASELINKs at all: it delegates to tsubst_copy
which then immediately exits early due to the empty args. This means
that the CAST_EXPR int(1) in the BASELINK A::condition<int(1)> never
gets folded (as part of folding of the overall CALL_EXPR), which later
causes us to crash when performing overload resolution of the rebuilt
CALL_EXPR (which is still in terms of this templated BASELINK).
This doesn't happen when condition() is a namespace-scope function
because then condition<int(1)> is represented by a TEMPLATE_ID_EXPR
rather than by a BASELINK, which does get handled directly from
tsubst_copy_and_build.
This patch fixes this issue by having tsubst_copy_and_build handle
BASELINK directly rather than delegating to tsubst_copy, so that it
processes BASELINKs even when args is empty.
gcc/cp/ChangeLog:
PR c++/95468
* pt.c (tsubst_copy_and_build) <case BASELINK>: New case, copied
over from tsubst_copy.
gcc/testsuite/ChangeLog:
PR c++/95468
* g++.dg/template/non-dependent15.C: New test.
case SCOPE_REF:
RETURN (tsubst_qualified_id (t, args, complain, in_decl, /*done=*/true,
/*address_p=*/false));
+
+ case BASELINK:
+ RETURN (tsubst_baselink (t, current_nonlambda_class_type (),
+ args, complain, in_decl));
+
case ARRAY_REF:
op1 = tsubst_non_call_postfix_expression (TREE_OPERAND (t, 0),
args, complain, in_decl);
--- /dev/null
+// PR c++/95468
+// { dg-do compile { target c++11 } }
+
+struct A {
+ template <int N>
+ static constexpr int condition() { return N; }
+};
+
+template <int> struct B {};
+
+template <class>
+using T = B<A::condition<int(1)>()>;