c++: check alias match for specializations [PR98116]

This fixes the underlying problem my recent (backedout) changes to
array type creation uncovered.  We had paths through
structural_comptypes that ignored alias templates, even when
significant.  This adds the necessary checks.

	PR c++/98116
	gcc/cp/
	* typeck.c (structural_comptypes): Move early outs to comptype.
	Always check template-alias match when comparing_specializations.
	(comptypes): Do early out checking here.
	gcc/testsuite/
	* g++.dg/template/pr98116.C: Remove dg-ice.
	* g++.dg/template/pr98116-2.C: New.

2 files changed, 36 insertions, 3 deletions

diff --git a/gcc/testsuite/g++.dg/template/pr98116-2.C b/gcc/testsuite/g++.dg/template/pr98116-2.C
new file mode 100644
index 0000000..fd12bb1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/pr98116-2.C
@@ -0,0 +1,34 @@
+// PR 98116, ICE with stripping typedef array type
+// { dg-do compile { target c++11 } }
+// { dg-additional-options {--param=hash-table-verification-limit=10000000 -fchecking=2} }
+
+// We got confused by alias templates that alias the same type.  Their
+// hashes were different (good), but they compared equal (bad)
+
+namespace std {
+typedef int is_convertible;
+template <typename _Tp> using remove_pointer_t = typename _Tp ::type;
+template <bool> struct enable_if;
+template <typename> void declval();
+template <bool _Cond> using enable_if_t = typename enable_if<_Cond>::type;
+template <typename, typename> class Trans_NS___cxx11_basic_string {
+  long _M_string_length;
+};
+} // namespace std
+struct string16_char_traits;
+template class std::Trans_NS___cxx11_basic_string<unsigned short,
+                                                  string16_char_traits>;
+template <typename, typename> using IsLegalDataConversion = std::is_convertible;
+template <typename Container, typename T>
+using ContainerHasConvertibleData = IsLegalDataConversion<
+    std::remove_pointer_t<decltype(std::declval<Container>)>, T>;
+template <typename Array, typename T, long>
+using EnableIfSpanCompatibleArray =
+  std::enable_if_t<!!sizeof (ContainerHasConvertibleData<Array, T>)>;
+template <int Extent> class span {
+  template <long N, EnableIfSpanCompatibleArray<
+                        const std::Trans_NS___cxx11_basic_string<
+                            unsigned short, string16_char_traits>[N],
+                        std::Trans_NS___cxx11_basic_string<short, int>, Extent>>
+  span();
+};
diff --git a/gcc/testsuite/g++.dg/template/pr98116.C b/gcc/testsuite/g++.dg/template/pr98116.C
index 874c590..7d54314 100644
--- a/gcc/testsuite/g++.dg/template/pr98116.C
+++ b/gcc/testsuite/g++.dg/template/pr98116.C
@@ -1,10 +1,9 @@
 // PR 98116, ICE with stripping typedef array type
 // { dg-do compile { target c++11 } }
 // { dg-additional-options {--param=hash-table-verification-limit=10000000 -fchecking=2} }
-// { dg-ice "spec_hasher::equal" }
 
-// We get confused by alias templates that alias the same type.
-// { dg-prune-output "hash table checking failed" }
+// We got confused by alias templates that alias the same type.  Their
+// hashes were different (good), but they compared equal (bad)
 
 namespace std {
 struct is_convertible;