re PR c++/53184 (Unnecessary anonymous namespace warnings)

2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/53184
	* doc/invoke.texi ([Wsubobject-linkage]): Document.

/c-family
2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/53184
	* c.opt ([Wsubobject-linkage]): Add.

/cp
2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/53184
	* decl2.c (constrain_class_visibility): Use Wsubobject-linkage.

/testsuite
2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/53184
	* g++.dg/warn/Wsubobject-linkage-1.C: New.
	* g++.dg/warn/Wsubobject-linkage-2.C: Likewise.
	* g++.dg/warn/Wsubobject-linkage-3.C: Likewise.
	* g++.dg/warn/Wsubobject-linkage-4.C: Likewise.

From-SVN: r227593

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/53184
+	* doc/invoke.texi ([Wsubobject-linkage]): Document.
+
 2015-09-09  Tom de Vries  <tom@codesourcery.com>
 
 	* params-list.h: Add missing copyright notice.

gcc/c-family/ChangeLog

@@ -1,3 +1,8 @@
+2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/53184
+	* c.opt ([Wsubobject-linkage]): Add.
+
 2015-09-03  Martin Sebor  <msebor@redhat.com>
 
 	PR c/66516

gcc/c-family/c.opt

@@ -944,6 +944,11 @@ Wuseless-cast
 C++ ObjC++ Var(warn_useless_cast) Warning
 Warn about useless casts
 
+Wsubobject-linkage
+C++ ObjC++ Var(warn_subobject_linkage) Warning Init(1)
+Warn if a class type has a base or a field whose type uses the anonymous
+namespace or depends on a type with no linkage
+
 ansi
 C ObjC C++ ObjC++
 A synonym for -std=c89 (for C) or -std=c++98 (for C++)

gcc/cp/ChangeLog

@@ -1,3 +1,8 @@
+2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/53184
+	* decl2.c (constrain_class_visibility): Use Wsubobject-linkage.
+
 2015-09-09  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/67504

gcc/cp/decl2.c

@@ -2564,10 +2564,25 @@ constrain_class_visibility (tree type)
 
 	if (subvis == VISIBILITY_ANON)
 	  {
-	    if (!in_main_input_context ())
+	    if (!in_main_input_context())
-	      warning (0, "\
+	      {
+		tree nlt = no_linkage_check (ftype, /*relaxed_p=*/false);
+		if (nlt)
+		  {
+		    if (same_type_p (TREE_TYPE (t), nlt))
+		      warning (OPT_Wsubobject_linkage, "\
+%qT has a field %qD whose type has no linkage",
+			       type, t);
+		    else
+		      warning (OPT_Wsubobject_linkage, "\
+%qT has a field %qD whose type depends on the type %qT which has no linkage",
+			       type, t, nlt);
+		  }
+		else
+		  warning (OPT_Wsubobject_linkage, "\
 %qT has a field %qD whose type uses the anonymous namespace",
-		       type, t);
+			   type, t);
+	      }
 	  }
 	else if (MAYBE_CLASS_TYPE_P (ftype)
 		 && vis < VISIBILITY_HIDDEN
@@ -2585,9 +2600,24 @@ constrain_class_visibility (tree type)
       if (subvis == VISIBILITY_ANON)
         {
 	  if (!in_main_input_context())
-	    warning (0, "\
+	    {
+	      tree nlt = no_linkage_check (TREE_TYPE (t), /*relaxed_p=*/false);
+	      if (nlt)
+		{
+		  if (same_type_p (TREE_TYPE (t), nlt))
+		    warning (OPT_Wsubobject_linkage, "\
+%qT has a base %qT whose type has no linkage",
+			     type, TREE_TYPE (t));
+		  else
+		    warning (OPT_Wsubobject_linkage, "\
+%qT has a base %qT whose type depends on the type %qT which has no linkage",
+			     type, TREE_TYPE (t), nlt);
+		}
+	      else
+		warning (OPT_Wsubobject_linkage, "\
 %qT has a base %qT whose type uses the anonymous namespace",
-		     type, TREE_TYPE (t));
+			 type, TREE_TYPE (t));
+	    }
 	}
       else if (vis < VISIBILITY_HIDDEN
 	       && subvis >= VISIBILITY_HIDDEN)

gcc/doc/invoke.texi

@@ -282,7 +282,7 @@ Objective-C and Objective-C++ Dialects}.
 -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 -Wsuggest-override @gol
--Wmissing-format-attribute @gol
+-Wmissing-format-attribute -Wsubobject-linkage @gol
 -Wswitch  -Wswitch-default  -Wswitch-enum -Wswitch-bool -Wsync-nand @gol
 -Wsystem-headers  -Wtautological-compare  -Wtrampolines  -Wtrigraphs @gol
 -Wtype-limits  -Wundef @gol
@@ -4923,6 +4923,13 @@ types. @option{-Wconversion-null} is enabled by default.
 Warn when a literal '0' is used as null pointer constant.  This can
 be useful to facilitate the conversion to @code{nullptr} in C++11.
 
+@item -Wsubobject-linkage @r{(C++ and Objective-C++ only)}
+@opindex Wsubobject-linkage
+@opindex Wno-subobject-linkage
+Warn if a class type has a base or a field whose type uses the anonymous
+namespace or depends on a type with no linkage.  This warning is
+enabled by default.
+
 @item -Wdate-time
 @opindex Wdate-time
 @opindex Wno-date-time

gcc/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2015-09-09  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/53184
+	* g++.dg/warn/Wsubobject-linkage-1.C: New.
+	* g++.dg/warn/Wsubobject-linkage-2.C: Likewise.
+	* g++.dg/warn/Wsubobject-linkage-3.C: Likewise.
+	* g++.dg/warn/Wsubobject-linkage-4.C: Likewise.
+
 2015-09-09  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* gcc.target/aarch64/mod_2.x: New file.

gcc/testsuite/g++.dg/warn/Wsubobject-linkage-1.C

@@ -0,0 +1,9 @@
+// PR c++/53184
+
+typedef volatile struct { } Foo;
+
+#line 6 "foo.C"
+struct Bar { Foo foo; };   // { dg-warning "no linkage" }
+// { dg-bogus "anonymous namespace" "" { target *-*-* } 6 }
+struct Bar2 : Foo { };     // { dg-warning "no linkage" }
+// { dg-bogus "anonymous namespace" "" { target *-*-* } 8 }

gcc/testsuite/g++.dg/warn/Wsubobject-linkage-2.C

@@ -0,0 +1,8 @@
+// PR c++/53184
+// { dg-options "-Wno-subobject-linkage" }
+
+typedef volatile struct { } Foo;
+
+#line 7 "foo.C"
+struct Bar { Foo foo; };
+struct Bar2 : Foo { };

gcc/testsuite/g++.dg/warn/Wsubobject-linkage-3.C

@@ -0,0 +1,9 @@
+// PR c++/53184
+
+namespace { struct Foo { }; }
+
+#line 6 "foo.C"
+struct Bar { Foo foo; };   // { dg-warning "anonymous namespace" }
+// { dg-bogus "no linkage" "" { target *-*-* } 6 }
+struct Bar2 : Foo { };     // { dg-warning "anonymous namespace" }
+// { dg-bogus "no linkage" "" { target *-*-* } 8 }

gcc/testsuite/g++.dg/warn/Wsubobject-linkage-4.C

@@ -0,0 +1,8 @@
+// PR c++/53184
+// { dg-options "-Wno-subobject-linkage" }
+
+namespace { struct Foo { }; }
+
+#line 7 "foo.C"
+struct Bar { Foo foo; };
+struct Bar2 : Foo { };