c++: noexcept error recursion [PR100101]

Here instantiating the noexcept-specifier for bar<void>() means
instantiating A<void>::value, which complains about the conversion from 0 to
int* in the default argument of foo.  Since my patch for PR99583, printing
the error context involves looking at C<void>::type, which again wants to
instantiate A<void>::value, which breaks.  For now at least, let's break
this recursion by avoiding looking into the noexcept-specifier in
find_typenames, and limit that to just the uses_parameter_packs case that
PR99583 cares about.

gcc/cp/ChangeLog:

	PR c++/100101
	PR c++/99583
	* pt.c (find_parameter_packs_r) [FUNCTION_TYPE]: Walk into
	TYPE_RAISES_EXCEPTIONS here.
	* tree.c (cp_walk_subtrees): Not here.

gcc/testsuite/ChangeLog:

	PR c++/100101
	* g++.dg/cpp0x/noexcept67.C: New test.

1 files changed, 26 insertions, 0 deletions

diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept67.C b/gcc/testsuite/g++.dg/cpp0x/noexcept67.C
new file mode 100644
index 0000000..7f06103
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept67.C
@@ -0,0 +1,26 @@
+// PR c++/100101
+// { dg-do compile { target c++11 } }
+
+template <typename T> struct A
+{
+    template <typename U> static char foo(U*, int* = 0);
+    static const bool value = sizeof(foo(static_cast<T*>(nullptr))) > 0;
+};
+
+template <bool b> struct B
+{
+    static const bool value = b;
+};
+
+template <typename T> struct C
+{
+    typedef B<A<T>::value> type;
+};
+
+template <typename T>
+void bar() noexcept(A<T>::value && C<T>::type::value) {}
+
+void baz()
+{
+  bar<void>();
+}