c++: deleted fn and noexcept inst [PR101532, PR104225]

Here when attempting to use B's implicitly deleted default constructor,
mark_used rightfully returns false, but for the wrong reason: it
tries to instantiate the synthesized noexcept specifier which then only
silently fails because get_defaulted_eh_spec suppresses diagnostics
for deleted functions.  This lack of diagnostics causes us to crash on
the first testcase below (thanks to the assert in finish_expr_stmt), and
silently accept the second testcase.

To fix this, this patch makes mark_used avoid attempting to instantiate
the noexcept specifier of a deleted function, so that we'll instead
directly reject (and diagnose) the function due to its deletedness.

	PR c++/101532
	PR c++/104225

gcc/cp/ChangeLog:

	* decl2.c (mark_used): Don't consider maybe_instantiate_noexcept
	on a deleted function.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/nsdmi-template21.C: New test.
	* g++.dg/cpp0x/nsdmi-template21a.C: New test.

(cherry picked from commit bc90dd0ecf02e11d47d1af7f627e2e2acaa40106)

3 files changed, 19 insertions, 0 deletions

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 672bd62f1ce..b64a4d7caa1 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -5403,6 +5403,7 @@ mark_used (tree decl, tsubst_flags_t complain)
     used_types_insert (DECL_CONTEXT (decl));
 
   if (TREE_CODE (decl) == FUNCTION_DECL
+      && !DECL_DELETED_FN (decl)
       && !maybe_instantiate_noexcept (decl, complain))
     return false;
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C
new file mode 100644
index 00000000000..79d43a54153
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C
@@ -0,0 +1,8 @@
+// PR c++/101532
+// { dg-do compile { target c++11 } }
+
+struct A { private: ~A(); };
+
+template<class> struct B { A a = A(); }; // { dg-error "private" }
+
+B<int> b; // { dg-error "deleted" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21a.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21a.C
new file mode 100644
index 00000000000..08fd37b8035
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21a.C
@@ -0,0 +1,10 @@
+// PR c++/104225
+// { dg-do compile { target c++11 } }
+
+struct A { private: ~A(); };
+
+template<class> struct B { A a = A(); }; // { dg-error "private" }
+
+int main() {
+  new B<int>; // { dg-error "deleted" }
+}