re PR c++/54532 ([C++0x][constexpr] internal error when initializing static…

re PR c++/54532 ([C++0x][constexpr] internal error when initializing static constexpr with pointer to non-static member variable)

	PR c++/54532
	* expr.c (cplus_expand_constant): Do nothing if the class is
	incomplete.
	* semantics.c (reduced_constant_expression_p): Allow PTRMEM_CST.
	* typeck2.c (store_init_value): Use reduced_constant_expression_p.
	* decl.c (maybe_register_incomplete_var): Handle PTRMEM_CST.
	(complete_vars): Likewise.

From-SVN: r196852

gcc/cp/ChangeLog

 2013-03-20  Jason Merrill  <jason@redhat.com>
 
+	PR c++/54532
+	* expr.c (cplus_expand_constant): Do nothing if the class is
+	incomplete.
+	* semantics.c (reduced_constant_expression_p): Allow PTRMEM_CST.
+	* typeck2.c (store_init_value): Use reduced_constant_expression_p.
+	* decl.c (maybe_register_incomplete_var): Handle PTRMEM_CST.
+	(complete_vars): Likewise.
+
 	* name-lookup.c (get_anonymous_namespace_name): Never use
 	get_file_function_name.
 

gcc/cp/decl.c

@@ -14018,7 +14018,10 @@ grokmethod (cp_decl_specifier_seq *declspecs,
 
 
 /* VAR is a VAR_DECL.  If its type is incomplete, remember VAR so that
-   we can lay it out later, when and if its type becomes complete.  */
+   we can lay it out later, when and if its type becomes complete.
+
+   Also handle constexpr pointer to member variables where the initializer
+   is an unlowered PTRMEM_CST because the class isn't complete yet.  */
 
 void
 maybe_register_incomplete_var (tree var)
@@ -14043,6 +14046,15 @@ maybe_register_incomplete_var (tree var)
 	  incomplete_var iv = {var, inner_type};
 	  vec_safe_push (incomplete_vars, iv);
 	}
+      else if (TYPE_PTRMEM_P (inner_type)
+	       && DECL_INITIAL (var)
+	       && TREE_CODE (DECL_INITIAL (var)) == PTRMEM_CST)
+	{
+	  tree context = TYPE_PTRMEM_CLASS_TYPE (inner_type);
+	  gcc_assert (TYPE_BEING_DEFINED (context));
+	  incomplete_var iv = {var, context};
+	  vec_safe_push (incomplete_vars, iv);
+	}
     }
 }
 
@@ -14062,10 +14074,17 @@ complete_vars (tree type)
 	{
 	  tree var = iv->decl;
 	  tree type = TREE_TYPE (var);
-	  /* Complete the type of the variable.  The VAR_DECL itself
-	     will be laid out in expand_expr.  */
-	  complete_type (type);
-	  cp_apply_type_quals_to_decl (cp_type_quals (type), var);
+
+	  if (TYPE_PTRMEM_P (type))
+	    DECL_INITIAL (var) = cplus_expand_constant (DECL_INITIAL (var));
+	  else
+	    {
+	      /* Complete the type of the variable.  The VAR_DECL itself
+		 will be laid out in expand_expr.  */
+	      complete_type (type);
+	      cp_apply_type_quals_to_decl (cp_type_quals (type), var);
+	    }
+
 	  /* Remove this entry from the list.  */
 	  incomplete_vars->unordered_remove (ix);
 	}

gcc/cp/expr.c

@@ -43,6 +43,10 @@ cplus_expand_constant (tree cst)
 	/* Find the member.  */
 	member = PTRMEM_CST_MEMBER (cst);
 
+	/* We can't lower this until the class is complete.  */
+	if (!COMPLETE_TYPE_P (DECL_CONTEXT (member)))
+	  return cst;
+
 	if (TREE_CODE (member) == FIELD_DECL)
 	  {
 	    /* Find the offset for the field.  */

gcc/cp/semantics.c

@@ -6838,6 +6838,9 @@ cxx_eval_call_expression (const constexpr_call *old_call, tree t,
 bool
 reduced_constant_expression_p (tree t)
 {
+  if (TREE_CODE (t) == PTRMEM_CST)
+    /* Even if we can't lower this yet, it's constant.  */
+    return true;
   /* FIXME are we calling this too much?  */
   return initializer_constant_valid_p (t, TREE_TYPE (t)) != NULL_TREE;
 }

gcc/cp/typeck2.c

@@ -792,7 +792,7 @@ store_init_value (tree decl, tree init, vec<tree, va_gc>** cleanups, int flags)
      will perform the dynamic initialization.  */
   if (value != error_mark_node
       && (TREE_SIDE_EFFECTS (value)
-	   || ! initializer_constant_valid_p (value, TREE_TYPE (value))))
+	  || ! reduced_constant_expression_p (value)))
     {
       if (TREE_CODE (type) == ARRAY_TYPE
 	  && TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (type)))

gcc/testsuite/g++.dg/cpp0x/constexpr-static11.C

+// PR c++/54532
+// { dg-do compile { target c++11 } }
+
+#define SA(X) static_assert(X,#X)
+
+struct A {
+  int i;
+  constexpr static int A::*p = &A::i;
+};
+
+constexpr A a = { 42 };
+SA(a.*A::p == 42);
+
+constexpr int A::* A::p;