PR c++/92590 - wrong handling of inherited default ctor.

I thought my earlier fix for 91930 was an obvious bug fix, but apparently an
inherited constructor does not count as user-declared.  So this patch
reverts that change and the other follow-on patches, and fixes 91930
differently, by not letting the inherited default constructor hide the
implicitly-declared default constructor.

	* class.c (add_method): A constrained inherited ctor doesn't hide an
	implicit derived ctor.

	Revert:
	PR c++/91930 - ICE with constrained inherited default ctor.
	* name-lookup.c (do_class_using_decl): Set TYPE_HAS_USER_CONSTRUCTOR
	for inherited constructor.
	PR c++/92552 - ICE with inherited constrained default ctor.
	* pt.c (instantiate_class_template_1): Copy
	TYPE_HAS_USER_CONSTRUCTOR.
	PR c++/92594 - ICE with inherited trivial default ctor.
	* method.c (trivial_fn_p): Treat an inherited default constructor
	like a normal default constructor.

5 files changed, 18 insertions, 10 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 3cc7c48..c137539 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -14,6 +14,20 @@
 
 2020-01-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/92590 - wrong handling of inherited default ctor.
+	* class.c (add_method): A constrained inherited ctor doesn't hide an
+	implicit derived ctor.
+	Revert:
+	PR c++/92552 - ICE with inherited constrained default ctor.
+	* pt.c (instantiate_class_template_1): Copy
+	TYPE_HAS_USER_CONSTRUCTOR.
+	PR c++/91930 - ICE with constrained inherited default ctor.
+	* name-lookup.c (do_class_using_decl): Set TYPE_HAS_USER_CONSTRUCTOR
+	for inherited constructor.
+	PR c++/92594 - ICE with inherited trivial default ctor.
+	* method.c (trivial_fn_p): Treat an inherited default constructor
+	like a normal default constructor.
+
 	PR c++/92594 - ICE with inherited trivial default ctor.
 	* method.c (trivial_fn_p): Treat an inherited default constructor
 	like a normal default constructor.
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 07abe52..719c3ec 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -1079,9 +1079,10 @@ add_method (tree type, tree method, bool via_using)
 	    {
 	      special_function_kind sfk = special_memfn_p (method);
 
-	      if (sfk == sfk_none)
+	      if (sfk == sfk_none || DECL_INHERITED_CTOR (fn))
 		/* Non-special member functions coexist if they are not
-		   equivalently constrained.  */
+		   equivalently constrained.  A member function is not hidden
+		   by an inherited constructor.  */
 		continue;
 
 	      /* P0848: For special member functions, deleted, unsatisfied, or
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index e20a88f..fef19e1 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -458,12 +458,7 @@ trivial_fn_p (tree fn)
   /* If fn is a clone, get the primary variant.  */
   if (tree prim = DECL_CLONED_FUNCTION (fn))
     fn = prim;
-  special_function_kind sfk = special_function_p (fn);
-  /* An inherited default constructor is equivalent to a non-inherited default
-     constructor, so let it be trivial.  */
-  if (sfk == sfk_inheriting_constructor && default_ctor_p (fn))
-    sfk = sfk_constructor;
-  return type_has_trivial_fn (DECL_CONTEXT (fn), sfk);
+  return type_has_trivial_fn (DECL_CONTEXT (fn), special_function_p (fn));
 }
 
 /* PARM is a PARM_DECL for a function which we want to forward to another
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 3c2c50d..cd7a581 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -4634,7 +4634,6 @@ lookup_using_decl (tree scope, name_lookup &lookup)
 	  maybe_warn_cpp0x (CPP0X_INHERITING_CTORS);
 	  lookup.name = ctor_identifier;
 	  CLASSTYPE_NON_AGGREGATE (current) = true;
-	  TYPE_HAS_USER_CONSTRUCTOR (current) = true;
     	}
 
       /* Cannot introduce a constructor name.  */
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 4fdc74f..7e675ce 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -11578,7 +11578,6 @@ instantiate_class_template_1 (tree type)
   SET_TYPE_ALIGN (type, TYPE_ALIGN (pattern));
   TYPE_USER_ALIGN (type) = TYPE_USER_ALIGN (pattern);
   CLASSTYPE_NON_AGGREGATE (type) = CLASSTYPE_NON_AGGREGATE (pattern);
-  TYPE_HAS_USER_CONSTRUCTOR (type) = TYPE_HAS_USER_CONSTRUCTOR (pattern);
   if (ANON_AGGR_TYPE_P (pattern))
     SET_ANON_AGGR_TYPE_P (type);
   if (CLASSTYPE_VISIBILITY_SPECIFIED (pattern))