PR c++/90047 - ICE with enable_if alias template.

In order to make alias templates useful for SFINAE we instantiate them under
the prevailing 'complain' argument, so an error encountered while
instantiating during SFINAE context is silent.  The problem in this PR comes
when we later look up the erroneous instantiation and don't give an error at
that point.  Fixed by not adding an erroneous instantiation to the hash
table, so we instantiate it again when needed and get the error.  This
required changes to a number of tests, which previously said "substitution
failed:" with no explanation of what the failure was; now we properly
explain.

	* pt.c (tsubst_decl) [TYPE_DECL]: Don't put an erroneous decl in the
	hash table when we're in SFINAE context.

From-SVN: r270433

gcc/cp/ChangeLog

@@ -1,3 +1,9 @@
+2019-04-17  Jason Merrill  <jason@redhat.com>
+
+	PR c++/90047 - ICE with enable_if alias template.
+	* pt.c (tsubst_decl) [TYPE_DECL]: Don't put an erroneous decl in the
+	hash table when we're in SFINAE context.
+
 2019-04-17  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/90124 - bogus error with incomplete type in decltype.

gcc/cp/pt.c

@@ -13948,7 +13948,8 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
 
 	    DECL_TEMPLATE_INFO (r) = build_template_info (tmpl, argvec);
 	    SET_DECL_IMPLICIT_INSTANTIATION (r);
-	    register_specialization (r, gen_tmpl, argvec, false, hash);
+	    if (!error_operand_p (r) || (complain & tf_error))
+	      register_specialization (r, gen_tmpl, argvec, false, hash);
 	  }
 	else
 	  {

gcc/testsuite/g++.dg/cpp0x/alias-decl-67.C

@@ -0,0 +1,30 @@
+// PR c++/90047
+// { dg-do compile { target c++11 } }
+
+template <int a> struct b { static constexpr int c = a; };
+template <typename> struct aa;
+template <typename...> struct d;
+template <typename e, typename f, typename g, typename... h>
+struct d<e, f, g, h...> : aa<e>::i {};
+template <typename> struct j;
+template <typename k, long l> struct j<k[l]> : b<true> {};
+struct m {
+  typedef b<0> i;
+};
+template <typename> struct n : m::i {};
+template <bool> struct o;
+template <typename p> struct aa { typedef p i; };
+template <bool ab> using ac = typename o<ab>::i; // { dg-error "incomplete" }
+class q {
+  template <typename k, typename> using ad = ac<d<n<k>, int, int>::c>;
+  template <typename k, typename = ad<k, void>> q(k &);
+};
+template <typename r> struct s {
+  s(r) { t; }
+  template <ac<!j<r>::c> *> void t();
+};
+class I {
+  friend char operator<<(char p1, I p2) { return p1 << p2; }
+  q ag;
+};
+int main() { s<char[10]> a = (char *)""; }

gcc/testsuite/g++.old-deja/g++.robertl/eb43.C

@@ -42,3 +42,5 @@ int main()
   sort( a.begin(), a.end(),
 	pointer_to_binary_function<const Expr<int>, const Expr<int>, bool>(compare<>) );
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/duration/arithmetic/dr3050.cc

@@ -28,3 +28,5 @@ void test01(std::chrono::seconds s, X x)
   s / x; // { dg-error "no match" }
   s % x; // { dg-error "no match" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/from_chars/1_c++20_neg.cc

@@ -36,3 +36,5 @@ test01(const char* first, const char* last)
   std::from_chars(first, last, c32); // { dg-error "no matching" }
   std::from_chars(first, last, c32, 10); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/from_chars/1_neg.cc

@@ -36,3 +36,5 @@ test01(const char* first, const char* last)
   std::from_chars(first, last, c32); // { dg-error "no matching" }
   std::from_chars(first, last, c32, 10); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/shared_ptr/assign/auto_ptr_neg.cc

@@ -47,3 +47,4 @@ main()
 }
 
 // { dg-prune-output "cannot convert" }
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/shared_ptr/assign/shared_ptr_neg.cc

@@ -35,3 +35,5 @@ test01()
   std::shared_ptr<B> b;
   a = b;                      // { dg-error "no match" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/shared_ptr/cons/unique_ptr_neg.cc

@@ -43,3 +43,4 @@ main()
   return 0;
 }
 // { dg-prune-output "initializing argument" }
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/to_chars/1_neg.cc

@@ -33,3 +33,5 @@ test01(char* first, char* last)
   std::to_chars(first, last, U'\x1'); // { dg-error "no matching" }
   std::to_chars(first, last, U'\x1', 10); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc

@@ -59,3 +59,5 @@ test03()
   std::get<6>(const_cast<const test_type&>(t));	// { dg-error "no match" }
   std::get<6>(static_cast<test_type&&>(t));	// { dg-error "no match" }
 }
+
+// { dg-prune-output "no type named .type" }

libstdc++-v3/testsuite/20_util/unique_ptr/cons/ptr_deleter_neg.cc

@@ -51,3 +51,5 @@ main()
   test02();
   return 0;
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/20_util/unique_ptr/modifiers/reset_neg.cc

@@ -55,3 +55,5 @@ test02()
   std::unique_ptr<const volatile A[]> cvA3;
   cvA3.reset(p); // { dg-error "no matching function" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/assign_neg.cc

@@ -32,3 +32,5 @@ void f()
   std::deque<A> d;
   d.assign(10, 1);		// { dg-error "no match|here" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/constructor_1_neg.cc

@@ -26,3 +26,5 @@ void f()
 {
   std::deque<std::deque<int> > d(10, 1); // { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/constructor_2_neg.cc

@@ -27,3 +27,5 @@ void f()
 {
   std::deque<std::deque<std::pair<char, char> > > d('a', 'b'); // { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/deque/requirements/dr438/insert_neg.cc

@@ -32,3 +32,5 @@ void f()
   std::deque<A> d;
   d.insert(d.begin(), 10, 1); // { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/forward_list/requirements/dr438/assign_neg.cc

@@ -30,3 +30,5 @@ void f()
   test_type l;
   l.assign(10, 1); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/forward_list/requirements/dr438/constructor_1_neg.cc

@@ -24,3 +24,5 @@ void f()
   typedef std::forward_list<std::forward_list<int> > test_type;
   test_type l(10, 1); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/forward_list/requirements/dr438/constructor_2_neg.cc

@@ -25,3 +25,5 @@ void f()
   typedef std::forward_list<std::forward_list<std::pair<char, char> > > test_type;
   test_type l('a', 'b'); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/forward_list/requirements/dr438/insert_neg.cc

@@ -30,3 +30,5 @@ void f()
   test_type l;
   l.insert_after(l.begin(), 10, 1); // { dg-error "no matching" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/list/requirements/dr438/assign_neg.cc

@@ -33,3 +33,5 @@ void f()
   list_type l;
   l.assign(10, 1);		// { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/list/requirements/dr438/constructor_1_neg.cc

@@ -27,3 +27,5 @@ void f()
   typedef std::list<std::list<int> > list_type;
   list_type l(10, 1);		// { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/list/requirements/dr438/constructor_2_neg.cc

@@ -28,3 +28,5 @@ void f()
   typedef std::list<std::list<std::pair<char, char> > > list_type;
   list_type l('a', 'b');	// { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/list/requirements/dr438/insert_neg.cc

@@ -33,3 +33,5 @@ void f()
   list_type l;
   l.insert(l.begin(), 10, 1);	// { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc

@@ -32,3 +32,5 @@ void f()
   std::vector<A> v;
   v.assign(10, 1);		// { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc

@@ -26,3 +26,5 @@ void f()
 {
   std::vector<std::vector<int> > v(10, 1); // { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc

@@ -27,3 +27,5 @@ void f()
 {
   std::vector<std::vector<std::pair<char, char> > > v('a', 'b'); // { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc

@@ -32,3 +32,5 @@ void f()
   std::vector<A> v;
   v.insert(v.begin(), 10, 1);	// { dg-error "here|no match" }
 }
+
+// { dg-prune-output "iterator_traits" }

libstdc++-v3/testsuite/experimental/memory/shared_ptr/cons/copy_ctor_neg.cc

@@ -50,3 +50,5 @@ main()
   test02();
   return 0;
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/experimental/memory/shared_ptr/cons/pointer_ctor_neg.cc

@@ -49,3 +49,5 @@ test03()
   B * const b = nullptr;
   std::experimental::shared_ptr<A[]> p(b); // { dg-error "no match" }
 }
+
+// { dg-prune-output "enable_if" }

libstdc++-v3/testsuite/experimental/memory/shared_ptr/modifiers/reset_neg.cc

@@ -43,3 +43,5 @@ test01()
   p1.reset(new constA[5]);      // { dg-error "no matching function" }
   p1.reset(new constA[5], D()); // { dg-error "no matching function" }
 }
+
+// { dg-prune-output "enable_if" }