[PATCH] pr31397 - implement -Wsuggest-override

[tbsaunde+gcc at tbsaunde dot org]

From: Trevor Saunders <tbsaunde+gcc@tbsaunde.org>

Hi,

comments fixed.  bootstrapped on x86_64-linux, new test passes and regtest
pending, ok?

Trev


c-family/

	* c.opt (Wsuggest-override): New option.

cp/

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

gcc/

	* doc/invoke.texi: Document -Wsuggest-override.

---
 gcc/c-family/c.opt                            |  5 +++++
 gcc/cp/class.c                                |  4 ++++
 gcc/doc/invoke.texi                           |  6 +++++-
 gcc/testsuite/g++.dg/warn/Wsuggest-override.C | 23 +++++++++++++++++++++++
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/warn/Wsuggest-override.C

diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index f86718b..1f6f793 100644
--- a/gcc/c-family/c.opt
+++ b/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
diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 0ac2124..d2cf4a0 100644
--- a/gcc/cp/class.c
+++ b/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))
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 9f56f42..d0ee093 100644
--- a/gcc/doc/invoke.texi
+++ b/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
@@ -4276,6 +4276,10 @@ 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
diff --git a/gcc/testsuite/g++.dg/warn/Wsuggest-override.C b/gcc/testsuite/g++.dg/warn/Wsuggest-override.C
new file mode 100644
index 0000000..f820f4b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wsuggest-override.C
@@ -0,0 +1,23 @@
+// { 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" }
+};
-- 
2.1.3