[C++ Patch] PR 67592 ("A virtual member function declared constexpr fails to trigger a diagnostic")

[Paolo Carlini]

Hi,

a simple issue: we fail to reject such declarations. While working on 
it, I noticed a tad of inconsistency in our error messages, where we 
have a mix of, eg, "... declared %<virtual%>..." and "... declared 
virtual...". I think we should prefer the former and spotted a few 
places needing adjustment. Tested x86_64-linux.

Thanks,
Paolo.

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-------------- next part --------------
/cp
2015-12-18  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/67592
	* decl.c (grokdeclarator): Reject constexpr virtual member functions;
	in error messages, prefer %<virtual%> and %<constexpr%> to virtual
	and constexpr, respectively.

/testsuite
2015-12-18  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/67592
	* g++.dg/cpp0x/constexpr-virtual5.C: New.
	* g++.dg/cpp0x/pr51463.C: Adjust dg-error string.
	* g++.dg/inherit/pure1.C: Likewise.
-------------- next part --------------
Index: cp/decl.c
===================================================================
--- cp/decl.c	(revision 231814)
+++ cp/decl.c	(working copy)
@@ -9769,11 +9769,18 @@ grokdeclarator (const cp_declarator *declarator,
   if (storage_class == sc_static)
     staticp = 1 + (decl_context == FIELD);
 
-  if (virtualp && staticp == 2)
+  if (virtualp)
     {
-      error ("member %qD cannot be declared both virtual and static", dname);
-      storage_class = sc_none;
-      staticp = 0;
+      if (staticp == 2)
+	{
+	  error ("member %qD cannot be declared both %<virtual%> "
+		 "and %<static%>", dname);
+	  storage_class = sc_none;
+	  staticp = 0;
+	}
+      if (constexpr_p)
+	error ("member %qD cannot be declared both %<virtual%> "
+	       "and %<constexpr%>", dname);
     }
   friendp = decl_spec_seq_has_spec_p (declspecs, ds_friend);
 
@@ -10153,7 +10160,8 @@ grokdeclarator (const cp_declarator *declarator,
 		      explicitp = 2;
 		    if (virtualp)
 		      {
-			permerror (input_location, "constructors cannot be declared virtual");
+			permerror (input_location,
+				   "constructors cannot be declared %<virtual%>");
 			virtualp = 0;
 		      }
 		    if (decl_context == FIELD
@@ -10988,7 +10996,7 @@ grokdeclarator (const cp_declarator *declarator,
 		   ARM 9.5 */
 		if (virtualp && TREE_CODE (ctype) == UNION_TYPE)
 		  {
-		    error ("function %qD declared virtual inside a union",
+		    error ("function %qD declared %<virtual%> inside a union",
 			   unqualified_id);
 		    return error_mark_node;
 		  }
@@ -10997,7 +11005,7 @@ grokdeclarator (const cp_declarator *declarator,
 		  {
 		    if (virtualp)
 		      {
-			error ("%qD cannot be declared virtual, since it "
+			error ("%qD cannot be declared %<virtual%>, since it "
 			       "is always static",
 			       unqualified_id);
 			virtualp = 0;
Index: testsuite/g++.dg/cpp0x/constexpr-virtual5.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-virtual5.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/constexpr-virtual5.C	(working copy)
@@ -0,0 +1,6 @@
+// PR c+++/67592
+// { dg-do compile { target c++11 } }
+
+struct S {
+  constexpr virtual int f() { return 1; }  // { dg-error "both 'virtual' and 'constexpr'" }
+};
Index: testsuite/g++.dg/cpp0x/pr51463.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr51463.C	(revision 231814)
+++ testsuite/g++.dg/cpp0x/pr51463.C	(working copy)
@@ -3,5 +3,5 @@
 
 struct A
 {
-  static virtual int i = 0;	// { dg-error "both virtual and static|declared as" }
+  static virtual int i = 0;	// { dg-error "both 'virtual' and 'static'|declared as" }
 };
Index: testsuite/g++.dg/inherit/pure1.C
===================================================================
--- testsuite/g++.dg/inherit/pure1.C	(revision 231814)
+++ testsuite/g++.dg/inherit/pure1.C	(working copy)
@@ -9,7 +9,7 @@ struct A
 {
   void foo2() = 0;                 // { dg-error "non-virtual" }
   static void foo3() = 0;          // { dg-error "static member" }
-  virtual static void foo4() = 0;  // { dg-error "both virtual and static" }
+  virtual static void foo4() = 0;  // { dg-error "both 'virtual' and 'static'" }
   virtual void foo5() = 0;         // { dg-error "base class" }
 };