implement -Wsuggest-override

c-family/

	PR c++/31397
	* c.opt (Wsuggest-override): New option.

cp/

	PR c++/31397
	* class.c (check_for_override): Warn when a virtual function is an
	override not marked override.

gcc/

	PR c++/31397
	* doc/invoke.texi: Document -Wsuggest-override.

From-SVN: r219213

gcc/ChangeLog

+2015-01-05  Trevor Saunders  <tsaunders@mozilla.com>
+
+	PR c++/31397
+	* doc/invoke.texi: Document -Wsuggest-override.
+
 2015-01-05  Radovan Obradovic  <radovan.obradovic@imgtec.com>
 
 	PR rtl-optimization/64287

gcc/c-family/ChangeLog

+2015-01-05  Trevor Saunders  <tsaunders@mozilla.com>
+
+	PR c++/31397
+	* c.opt (Wsuggest-override): New option.
+
 2015-01-05  Jakub Jelinek  <jakub@redhat.com>
 
 	Update copyright years.

gcc/c-family/c.opt

@@ -578,6 +578,11 @@ Wsuggest-attribute=format
 C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
 Warn about functions which might be candidates for format attributes
 
+Wsuggest-override
+C++ ObjC++ Var(warn_override) Warning
+Suggest that the override keyword be used when the declaration of a virtual
+function overrides another.
+
 Wswitch
 C ObjC C++ ObjC++ Var(warn_switch) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 Warn about enumerated switches, with no default, missing a case

gcc/cp/ChangeLog

 2015-01-05  Trevor Saunders  <tsaunders@mozilla.com>
 
+	PR c++/31397
+	* class.c (check_for_override): Warn when a virtual function is an
+	override not marked override.
+
+2015-01-05  Trevor Saunders  <tsaunders@mozilla.com>
+
 	* class.c (warn_hidden): Use auto_vec<tree> instead of tree_list to
 	hold base_fndecls.
 	(get_basefndecls): Adjust.

gcc/cp/class.c

@@ -2811,6 +2811,10 @@ check_for_override (tree decl, tree ctype)
     {
       DECL_VINDEX (decl) = decl;
       overrides_found = true;
+      if (warn_override && !DECL_OVERRIDE_P (decl)
+	  && !DECL_DESTRUCTOR_P (decl))
+	warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wsuggest_override,
+		    "%q+D can be marked override", decl);
     }
 
   if (DECL_VIRTUAL_P (decl))

gcc/doc/invoke.texi

@@ -277,7 +277,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wstack-protector -Wstack-usage=@var{len} -Wstrict-aliasing @gol
 -Wstrict-aliasing=n @gol -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
 -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]} @gol
--Wsuggest-final-types @gol -Wsuggest-final-methods @gol
+-Wsuggest-final-types @gol -Wsuggest-final-methods @gol -Wsuggest-override @gol
 -Wmissing-format-attribute @gol
 -Wswitch  -Wswitch-default  -Wswitch-enum -Wswitch-bool -Wsync-nand @gol
 -Wsystem-headers  -Wtrampolines  -Wtrigraphs  -Wtype-limits  -Wundef @gol
@@ -4282,6 +4282,10 @@ class hierarchy graph is more complete. It is recommended to first consider
 suggestions of @option{-Wsuggest-final-types} and then rebuild with new
 annotations.
 
+@item -Wsuggest-override
+Warn about overriding virtual functions that are not marked with the override
+keyword.
+
 @item -Warray-bounds
 @opindex Wno-array-bounds
 @opindex Warray-bounds

gcc/testsuite/g++.dg/warn/Wsuggest-override.C

+// { dg-do compile }
+// { dg-options "-std=c++11 -Wsuggest-override" }
+struct A
+{
+	A();
+	virtual ~A();
+	virtual void f();
+	virtual int bar();
+	int c();
+	operator int();
+	virtual operator float();
+};
+
+struct B : A
+{
+	B();
+	virtual ~B();
+	virtual void f(); // { dg-warning "can be marked override" }
+virtual int bar() override;
+int c();
+operator int();
+virtual operator float(); // { dg-warning "can be marked override" }
+};