C++ PATCH for c++/85470, wrong error with static data member

[Jason Merrill]

As Jakub suggested in the PR, these places that were checking
DECL_IN_AGGR_P really should have been checking
DECL_INITIALIZED_IN_CLASS_P.

Tested x86_64-pc-linux-gnu, applying to trunk.

commit f0c8d6d89ec136e9c35d057f742df5bbc397997d
Author: Jason Merrill <ja...@redhat.com>
Date:   Mon Apr 23 13:54:10 2018 -0400

            PR c++/85470 - wrong error with static data member.
    
            * decl.c (check_initializer): Check DECL_INITIALIZED_IN_CLASS_P.
            * typeck2.c (store_init_value): Likewise.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 9f1a171ead7..d822745b81f 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -6513,7 +6513,9 @@ check_initializer (tree decl, tree init, int flags, vec<tree, va_gc> **cleanups)
     }
 
   if (init_code
-      && (DECL_IN_AGGR_P (decl) && !DECL_VAR_DECLARED_INLINE_P (decl)))
+      && (DECL_IN_AGGR_P (decl)
+	  && DECL_INITIALIZED_IN_CLASS_P (decl)
+	  && !DECL_VAR_DECLARED_INLINE_P (decl)))
     {
       static int explained = 0;
 
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index e5f9a68ec58..37e78936103 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -824,9 +824,12 @@ store_init_value (tree decl, tree init, vec<tree, va_gc>** cleanups, int flags)
       bool const_init;
       value = fold_non_dependent_expr (value);
       if (DECL_DECLARED_CONSTEXPR_P (decl)
-	  || (DECL_IN_AGGR_P (decl) && !DECL_VAR_DECLARED_INLINE_P (decl)))
+	  || (DECL_IN_AGGR_P (decl)
+	      && DECL_INITIALIZED_IN_CLASS_P (decl)
+	      && !DECL_VAR_DECLARED_INLINE_P (decl)))
 	{
-	  /* Diagnose a non-constant initializer for constexpr.  */
+	  /* Diagnose a non-constant initializer for constexpr variable or
+	     non-inline in-class-initialized static data member.  */
 	  if (!require_constant_expression (value))
 	    value = error_mark_node;
 	  else
diff --git a/gcc/testsuite/g++.dg/cpp0x/extern_template-4.C b/gcc/testsuite/g++.dg/cpp0x/extern_template-4.C
new file mode 100644
index 00000000000..9f0c7d720ab
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/extern_template-4.C
@@ -0,0 +1,23 @@
+// PR c++/85470
+// { dg-do compile { target c++11 } }
+
+template <class T>
+struct StaticObject
+{
+    static T& create()
+    {
+      static T t;
+      return t;
+    }
+
+    static T & instance;
+};
+
+template <class T> T & StaticObject<T>::instance = StaticObject<T>::create();
+
+extern template class StaticObject<int>;
+
+void test()
+{
+    StaticObject<int>::instance;
+}