Here when instantiating the noexcept-spec we fail to resolve the
implicit object parameter for the call A<T>::f() ultimately because
maybe_instantiate_noexcept sets current_class_ptr/ref to the dependent
'this' (of type B<T>) rather than the specialized 'this' (of type B<int>).
This ends up causing maybe_dummy_object (called from
finish_qualified_id_expr) to return a dummy object instead of 'this'.

This patch corrects this by making maybe_instantiate_noexcept always set
current_class_ptr/ref to the specialized 'this', consistent with what
tsubst_function_type does when substituting into a trailing return type.

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk perhaps?

        PR c++/94944

gcc/cp/ChangeLog:

        * pt.cc (maybe_instantiate_noexcept): For non-static member
        functions, set current_class_ptr/ref to the specialized 'this'
        instead.

gcc/testsuite/ChangeLog:

        * g++.dg/cpp0x/noexcept34.C: Adjusted expected diagnostics.
        * g++.dg/cpp0x/noexcept75.C: New test.
---
 gcc/cp/pt.cc                            | 19 +++++++------------
 gcc/testsuite/g++.dg/cpp0x/noexcept34.C |  8 ++++----
 gcc/testsuite/g++.dg/cpp0x/noexcept75.C | 17 +++++++++++++++++
 3 files changed, 28 insertions(+), 16 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept75.C

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 6dda66081bd..a7a524fe9fc 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -26139,20 +26139,15 @@ maybe_instantiate_noexcept (tree fn, tsubst_flags_t 
complain)
          push_deferring_access_checks (dk_no_deferred);
          input_location = DECL_SOURCE_LOCATION (fn);
 
-         if (!DECL_LOCAL_DECL_P (fn))
+         if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn)
+             && !DECL_LOCAL_DECL_P (fn))
            {
              /* If needed, set current_class_ptr for the benefit of
-                tsubst_copy/PARM_DECL.  The exception pattern will
-                refer to the parm of the template, not the
-                instantiation.  */
-             tree tdecl = DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (fn));
-             if (DECL_NONSTATIC_MEMBER_FUNCTION_P (tdecl))
-               {
-                 tree this_parm = DECL_ARGUMENTS (tdecl);
-                 current_class_ptr = NULL_TREE;
-                 current_class_ref = cp_build_fold_indirect_ref (this_parm);
-                 current_class_ptr = this_parm;
-               }
+                tsubst_copy/PARM_DECL.  */
+             tree this_parm = DECL_ARGUMENTS (fn);
+             current_class_ptr = NULL_TREE;
+             current_class_ref = cp_build_fold_indirect_ref (this_parm);
+             current_class_ptr = this_parm;
            }
 
          /* If this function is represented by a TEMPLATE_DECL, then
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept34.C 
b/gcc/testsuite/g++.dg/cpp0x/noexcept34.C
index dce35652ef5..86129e7a520 100644
--- a/gcc/testsuite/g++.dg/cpp0x/noexcept34.C
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept34.C
@@ -7,13 +7,13 @@ template<typename> struct A
 {
   constexpr int f () { return 0; }
   bool b = true;
-  void g () noexcept (f()) { } // { dg-error "use of parameter" }
-  void g2 () noexcept (this->f()) { } // { dg-error "use of parameter" }
+  void g () noexcept (f()) { } // { dg-error ".this. is not a constant" }
+  void g2 () noexcept (this->f()) { } // { dg-error ".this. is not a constant" 
}
   void g3 () noexcept (b) { } // { dg-error "use of .this. in a constant 
expression|use of parameter" }
   void g4 (int i) noexcept (i) { } // { dg-error "use of parameter" }
-  void g5 () noexcept (A::f()) { } // { dg-error "use of parameter" }
+  void g5 () noexcept (A::f()) { } // { dg-error ".this. is not a constant" }
   void g6 () noexcept (foo(b)) { } // { dg-error "use of .this. in a constant 
expression|use of parameter" }
-  void g7 () noexcept (int{f()}) { } // { dg-error "use of parameter" }
+  void g7 () noexcept (int{f()}) { } // { dg-error ".this. is not a constant" }
 };
 
 int main ()
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept75.C 
b/gcc/testsuite/g++.dg/cpp0x/noexcept75.C
new file mode 100644
index 00000000000..d746f4768d0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept75.C
@@ -0,0 +1,17 @@
+// PR c++/94944
+// { dg-do compile { target c++11 } }
+
+template<class T>
+struct A {
+  void f();
+};
+
+template<class T>
+struct B : A<T> {
+  void g() noexcept(noexcept(A<T>::f()));
+};
+
+int main() {
+  B<int> b;
+  b.g();
+}
-- 
2.35.1.129.gb80121027d

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