PATCH RFA: Support -Wmissing-declarations in C++

[Ian Lance Taylor <iant at google dot com>]

Currently -Wmissing-declarations only works for C.  But it makes just
as much sense for C++ as it does for C.  This patch adds support for
-Wmissing-declarations in C++.

Tested with bootstrap and testsuite run on i686-pc-linux-gnu.

OK for mainline?

Ian


gcc/ChangeLog:

2006-12-14  Ian Lance Taylor  <iant@google.com>

	* c.opt (Wmissing-declarations): Add C++ and ObjC++.
	* doc/invoke.texi (Warning Options): -Wmissing-declarations now
	works for C++.

gcc/cp/ChangeLog:

2006-12-14  Ian Lance Taylor  <iant@google.com>

	* decl.c (start_preparsed_function): Add support for
	-Wmissing-declarations.

gcc/testsuite/ChangeLog:

2006-12-14  Ian Lance Taylor  <iant@google.com>

	* g++.dg/warn/Wmissing-declarations-1.C: New test.


Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 119818)
+++ gcc/doc/invoke.texi	(working copy)
@@ -3215,7 +3215,7 @@ declaration.  This warning is issued eve
 provides a prototype.  The aim is to detect global functions that fail
 to be declared in header files.
 
-@item -Wmissing-declarations @r{(C only)}
+@item -Wmissing-declarations @r{(C and C++ only)}
 @opindex Wmissing-declarations
 Warn if a global function is defined without a previous declaration.
 Do so even if the definition itself provides a prototype.
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c	(revision 119818)
+++ gcc/cp/decl.c	(working copy)
@@ -10570,9 +10570,40 @@ start_preparsed_function (tree decl1, tr
 	       parsing the body of the function.  */
 	    ;
 	  else
-	    /* Otherwise, OLDDECL is either a previous declaration of
-	       the same function or DECL1 itself.  */
-	    decl1 = olddecl;
+	    {
+	      /* Otherwise, OLDDECL is either a previous declaration
+		 of the same function or DECL1 itself.  */
+
+	      if (warn_missing_declarations
+		  && olddecl == decl1
+		  && !DECL_MAIN_P (decl1)
+		  && TREE_PUBLIC (decl1))
+		{
+		  bool anon;
+		  tree context;
+
+		  /* Check whether DECL1 is in an anonymous
+		     namespace.  */
+		  anon = false;
+		  for (context = DECL_CONTEXT (decl1);
+		       context;
+		       context = DECL_CONTEXT (context))
+		    {
+		      if (TREE_CODE (context) == NAMESPACE_DECL
+			  && DECL_NAME (context) == NULL_TREE)
+			{
+			  anon = true;
+			  break;
+			}
+		    }
+
+		  if (!anon)
+		    warning (OPT_Wmissing_declarations,
+			     "no previous declaration for %q+D", decl1);
+		}
+
+	      decl1 = olddecl;
+	    }
 	}
       else
 	{
Index: gcc/c.opt
===================================================================
--- gcc/c.opt	(revision 119818)
+++ gcc/c.opt	(working copy)
@@ -260,7 +260,7 @@ C ObjC C++ ObjC++ Var(warn_missing_brace
 Warn about possibly missing braces around initializers
 
 Wmissing-declarations
-C ObjC Var(warn_missing_declarations)
+C ObjC C++ ObjC++ Var(warn_missing_declarations)
 Warn about global functions without previous declarations
 
 Wmissing-field-initializers
Index: gcc/testsuite/g++.dg/warn/Wmissing-declarations-1.C
===================================================================
--- gcc/testsuite/g++.dg/warn/Wmissing-declarations-1.C	(revision 0)
+++ gcc/testsuite/g++.dg/warn/Wmissing-declarations-1.C	(revision 0)
@@ -0,0 +1,35 @@
+// { dg-options "-Wmissing-declarations" }
+
+int fn1() { }		// { dg-warning "no previous declaration" }
+namespace ns {
+  int fn2() { }		// { dg-warning "no previous declaration" }
+}
+namespace {
+  int fn3() { }
+}
+static int fn4() { }
+
+int fn5();
+namespace ns {
+  int fn6();
+}
+
+int fn5() { }
+namespace ns {
+  int fn6() { }
+}
+
+class c {
+  int cfn1() { }
+  static int cfn2() { }
+  int cfn3();
+  static int cfn4();
+};
+
+int c::cfn3() { }
+int c::cfn4() { }
+
+static struct {
+  int sfn1() { }
+  static int sfn2() { }
+} s;