PR c++/88136 - -Wdeprecated-copy false positives

Deprecating the copy operations because the class has a user-provided
destructor turns out to have too many false positives; this patch adjusts
-Wdeprecated-copy to only deprecate if the other copy operation is
user-provided.  To get the earlier behavior, people can explicitly request
it with -Wdeprecated-copy-dtor.

gcc/c-family/
	* c.opt (Wdeprecated-copy-dtor): New.
	(Wdeprecated-copy): Move to -Wextra.
gcc/cp/
	* class.c (classtype_has_depr_implicit_copy): Rename from
	classtype_has_user_copy_or_dtor.
	* method.c (lazily_declare_fn): Adjust.
	* decl2.c (cp_warn_deprecated_use): Refer to -Wdeprecated-copy-dtor
	if deprecation is due to a destructor.

From-SVN: r266867

gcc/c-family/ChangeLog

+2018-12-06  Jason Merrill  <jason@redhat.com>
+
+	PR c++/88136 - -Wdeprecated-copy false positives
+	* c.opt (Wdeprecated-copy-dtor): New.
+	(Wdeprecated-copy): Move to -Wextra.
+
 2018-11-29  Martin Sebor  <msebor@redhat.com>
 
 	PR c/88172

gcc/c-family/c.opt

@@ -481,7 +481,12 @@ C C++ ObjC ObjC++ CPP(cpp_warn_deprecated) CppReason(CPP_W_DEPRECATED) Var(warn_
 Warn if a deprecated compiler feature, class, method, or field is used.
 
 Wdeprecated-copy
-C++ ObjC++ Var(warn_deprecated_copy) Warning LangEnabledBy(C++ ObjC++, Wall)
+C++ ObjC++ Var(warn_deprecated_copy) Warning LangEnabledBy(C++ ObjC++, Wextra)
+Mark implicitly-declared copy operations as deprecated if the class has a
+user-provided copy operation.
+
+Wdeprecated-copy-dtor
+C++ ObjC++ Var(warn_deprecated_copy, 2) Warning
 Mark implicitly-declared copy operations as deprecated if the class has a
 user-provided copy operation or destructor.
 

gcc/cp/ChangeLog

+2018-12-06  Jason Merrill  <jason@redhat.com>
+
+	PR c++/88136 - -Wdeprecated-copy false positives
+	* class.c (classtype_has_depr_implicit_copy): Rename from
+	classtype_has_user_copy_or_dtor.
+	* method.c (lazily_declare_fn): Adjust.
+	* decl2.c (cp_warn_deprecated_use): Refer to -Wdeprecated-copy-dtor
+	if deprecation is due to a destructor.
+
 2018-12-06  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/88373 - wrong parse error with ~.

gcc/cp/class.c

@@ -5233,7 +5233,7 @@ classtype_has_non_deleted_move_ctor (tree t)
    operator, or destructor, returns that function.  Otherwise, null.  */
 
 tree
-classtype_has_user_copy_or_dtor (tree t)
+classtype_has_depr_implicit_copy (tree t)
 {
   if (!CLASSTYPE_LAZY_COPY_CTOR (t))
     for (ovl_iterator iter (CLASSTYPE_CONSTRUCTORS (t)); iter; ++iter)

gcc/cp/cp-tree.h

@@ -6273,7 +6273,7 @@ extern bool type_has_constexpr_default_constructor (tree);
 extern bool type_has_virtual_destructor		(tree);
 extern bool classtype_has_move_assign_or_move_ctor_p (tree, bool user_declared);
 extern bool classtype_has_non_deleted_move_ctor (tree);
-extern tree classtype_has_user_copy_or_dtor	(tree);
+extern tree classtype_has_depr_implicit_copy	(tree);
 extern bool type_build_ctor_call		(tree);
 extern bool type_build_dtor_call		(tree);
 extern void explain_non_literal_class		(tree);

gcc/cp/decl2.c

@@ -5298,18 +5298,23 @@ cp_warn_deprecated_use (tree decl, tsubst_flags_t complain)
       && DECL_NONSTATIC_MEMBER_FUNCTION_P (decl)
       && copy_fn_p (decl))
     {
-      auto_diagnostic_group d;
-      /* Don't warn about system library classes (c++/86342).  */
-      if (!DECL_IN_SYSTEM_HEADER (decl))
-	warned = warning (OPT_Wdeprecated_copy,
-			  "implicitly-declared %qD is deprecated", decl);
-      if (warned)
+      if (warn_deprecated_copy
+	  /* Don't warn about system library classes (c++/86342).  */
+	  && (!DECL_IN_SYSTEM_HEADER (decl)
+	      || global_dc->dc_warn_system_headers))
 	{
+	  auto_diagnostic_group d;
 	  tree ctx = DECL_CONTEXT (decl);
-	  tree other = classtype_has_user_copy_or_dtor (ctx);
-	  inform (DECL_SOURCE_LOCATION (other),
-		  "because %qT has user-provided %qD",
-		  ctx, other);
+	  tree other = classtype_has_depr_implicit_copy (ctx);
+	  int opt = (DECL_DESTRUCTOR_P (other)
+		     ? OPT_Wdeprecated_copy_dtor
+		     : OPT_Wdeprecated_copy);
+	  warned = warning (opt, "implicitly-declared %qD is deprecated",
+			    decl);
+	  if (warned)
+	    inform (DECL_SOURCE_LOCATION (other),
+		    "because %qT has user-provided %qD",
+		    ctx, other);
 	}
     }
   else

gcc/cp/method.c

@@ -2380,7 +2380,7 @@ lazily_declare_fn (special_function_kind sfk, tree type)
     {
       if (classtype_has_move_assign_or_move_ctor_p (type, true))
 	DECL_DELETED_FN (fn) = true;
-      else if (classtype_has_user_copy_or_dtor (type))
+      else if (classtype_has_depr_implicit_copy (type))
 	/* The implicit definition of a copy constructor as defaulted is
 	   deprecated if the class has a user-declared copy assignment operator
 	   or a user-declared destructor. The implicit definition of a copy

gcc/doc/invoke.texi

@@ -228,7 +228,8 @@ in the following sections.
 -fvisibility-ms-compat @gol
 -fext-numeric-literals @gol
 -Wabi=@var{n}  -Wabi-tag  -Wconversion-null  -Wctor-dtor-privacy @gol
--Wdelete-non-virtual-dtor  -Wdeprecated-copy  -Wliteral-suffix @gol
+-Wdelete-non-virtual-dtor  -Wdeprecated-copy  -Wdeprecated-copy-dtor @gol
+-Wliteral-suffix @gol
 -Wmultiple-inheritance  -Wno-init-list-lifetime @gol
 -Wnamespaces  -Wnarrowing @gol
 -Wpessimizing-move  -Wredundant-move @gol
@@ -3000,8 +3001,10 @@ by @option{-Wall}.
 @opindex Wno-deprecated-copy
 Warn that the implicit declaration of a copy constructor or copy
 assignment operator is deprecated if the class has a user-provided
-copy constructor, copy assignment operator, or destructor, in C++11
-and up.  This warning is enabled by @option{-Wall}.
+copy constructor or copy assignment operator, in C++11 and up.  This
+warning is enabled by @option{-Wextra}.  With
+@option{-Wdeprecated-copy-dtor}, also deprecate if the class has a
+user-provided destructor.
 
 @item -Wno-init-list-lifetime @r{(C++ and Objective-C++ only)}
 @opindex Winit-list-lifetime
@@ -4407,6 +4410,7 @@ name is still supported, but the newer name is more descriptive.)
 
 @gccoptlist{-Wclobbered  @gol
 -Wcast-function-type  @gol
+-Wdeprecated-copy @r{(C++ only)} @gol
 -Wempty-body  @gol
 -Wignored-qualifiers @gol
 -Wimplicit-fallthrough=3 @gol

gcc/testsuite/g++.dg/cpp0x/depr-copy1.C

@@ -6,7 +6,7 @@
    of this International Standard, these implicit definitions could become
    deleted (11.4).  */
 
-// { dg-additional-options -Wdeprecated-copy }
+// { dg-additional-options -Wdeprecated-copy-dtor }
 
 struct X
 {