diff mbox series

c++, v2: Disallow [[deprecated]] on types other than class/enum definitions [PR110345]

Message ID ZtICi8k0GbNdy21e@tucnak
State New
Headers show
Series c++, v2: Disallow [[deprecated]] on types other than class/enum definitions [PR110345] | expand

Commit Message

Jakub Jelinek Aug. 30, 2024, 5:34 p.m. UTC 
On Mon, Aug 19, 2024 at 05:05:51PM -0400, Jason Merrill wrote:
> > I've tried to compile it also with latest clang and there is agreement in
> > most of the diagnostics, just at block scope (inside of foo) it doesn't
> > diagnose
> >    auto e = new int [n] [[deprecated]];
> >    auto e2 = new int [n] [[deprecated]] [42];
> >    [[deprecated]] lab:;
> > and at namespace scope
> > [[deprecated]];
> > I think that all feels like clang++ bug.
> > On the other side, clang++ diagnoses
> > enum B { B0 } [[deprecated]];
> > but GCC with all the patches I've posted today doesn't, is that a GCC bug?
> 
> I think so, yes.

Fixed in the just posted 2 patches.

> > The FIXMEs are where there is agreement with clang++, but I'm not sure.
> > One thing is I'm not sure if "a variable" above is meant to include function
> > parameters, and/or unused function parameters without a specified name,
> > function parameters inside of a function declaration rather than definition
> > and/or static data members.
> 
> All of those, I believe.

Removed the FIXMEs.

> > Also unsure about
> >    [[deprecated]] int : 0;
> > at class scope, that isn't a non-static data member...
> 
> Indeed, pedantically the standard says it can't apply to an unnamed
> bit-field.

And the following updated version on top of the
https://gcc.gnu.org/pipermail/gcc-patches/2024-August/661904.html
https://gcc.gnu.org/pipermail/gcc-patches/2024-August/661905.html
patches also diagnoses the attribute on unnamed bit-fields.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2024-08-30  Jakub Jelinek  <jakub@redhat.com>

	PR c++/110345
	* parser.cc (cp_parser_std_attribute): Don't transform
	[[deprecated]] into [[gnu::deprecated]].
	* tree.cc (handle_std_deprecated_attribute): New function.
	(std_attributes): Add deprecated entry.

	* g++.dg/cpp0x/attr-deprecated1.C: New test.



	Jakub
diff mbox series

Patch

--- gcc/cp/parser.cc.jj	2024-08-30 11:13:18.612089567 +0200
+++ gcc/cp/parser.cc	2024-08-30 12:55:17.875362909 +0200
@@ -30357,12 +30357,11 @@  cp_parser_std_attribute (cp_parser *pars
 
       /* We used to treat C++11 noreturn attribute as equivalent to GNU's,
 	 but no longer: we have to be able to tell [[noreturn]] and
-	 __attribute__((noreturn)) apart.  */
-      /* C++14 deprecated attribute is equivalent to GNU's.  */
-      if (is_attribute_p ("deprecated", attr_id))
-	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
+	 __attribute__((noreturn)) apart.
+	 Similarly for C++14 deprecated attribute, we need to emit extra
+	 diagnostics for [[deprecated]] compared to [[gnu::deprecated]].  */
       /* C++17 fallthrough attribute is equivalent to GNU's.  */
-      else if (is_attribute_p ("fallthrough", attr_id))
+      if (is_attribute_p ("fallthrough", attr_id))
 	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
       /* C++23 assume attribute is equivalent to GNU's.  */
       else if (is_attribute_p ("assume", attr_id))
--- gcc/cp/tree.cc.jj	2024-08-15 22:23:07.908239976 +0200
+++ gcc/cp/tree.cc	2024-08-30 13:15:26.863829810 +0200
@@ -5087,6 +5087,25 @@  handle_likeliness_attribute (tree *node,
     return error_mark_node;
 }
 
+/* The C++14 [[deprecated]] attribute mostly maps to the GNU deprecated
+   attribute.  */
+
+static tree
+handle_std_deprecated_attribute (tree *node, tree name, tree args, int flags,
+				 bool *no_add_attrs)
+{
+  tree t = *node;
+  tree ret = handle_deprecated_attribute (node, name, args, flags,
+					  no_add_attrs);
+  if (TYPE_P (*node) && t != *node)
+    pedwarn (input_location, OPT_Wattributes,
+	     "%qE on a type other than class or enumeration definition", name);
+  else if (TREE_CODE (*node) == FIELD_DECL && DECL_UNNAMED_BIT_FIELD (*node))
+    pedwarn (input_location, OPT_Wattributes, "%qE on unnamed bit-field",
+	     name);
+  return ret;
+}
+
 /* Table of valid C++ attributes.  */
 static const attribute_spec cxx_gnu_attributes[] =
 {
@@ -5110,6 +5129,8 @@  static const attribute_spec std_attribut
 {
   /* { name, min_len, max_len, decl_req, type_req, fn_type_req,
        affects_type_identity, handler, exclude } */
+  { "deprecated", 0, 1, false, false, false, false,
+    handle_std_deprecated_attribute, NULL },
   { "maybe_unused", 0, 0, false, false, false, false,
     handle_unused_attribute, NULL },
   { "nodiscard", 0, 1, false, false, false, false,
--- gcc/testsuite/g++.dg/cpp0x/attr-deprecated1.C.jj	2024-08-30 12:55:17.877362884 +0200
+++ gcc/testsuite/g++.dg/cpp0x/attr-deprecated1.C	2024-08-30 16:05:10.939240604 +0200
@@ -0,0 +1,131 @@ 
+// C++ 26 P2552R3 - On the ignorability of standard attributes
+// { dg-do compile { target c++11 } }
+
+int arr[2];
+struct S { int a, b; };
+S arr2[2];
+
+void
+foo (int n)
+{
+  [[deprecated]] int x1;
+  [[deprecated ("foobar")]] int x2;
+  [[deprecated (0)]] int x3;			// { dg-error "deprecated message is not a string" }
+						// { dg-error "expected string-literal before numeric constant" "" { target c++26 } .-1 }
+  [[deprecated ("foo", "bar", "baz")]] int x4;	// { dg-error "wrong number of arguments specified for 'deprecated' attribute" }
+  [[deprecated (0, 1, 2)]] int x5;		// { dg-error "wrong number of arguments specified for 'deprecated' attribute" }
+						// { dg-error "expected string-literal before numeric constant" "" { target c++26 } .-1 }
+
+  auto a = [] [[deprecated]] () {};
+  auto b = [] constexpr [[deprecated]] {};	// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+						// { dg-error "parameter declaration before lambda declaration specifiers only optional with" "" { target c++20_down } .-1 }
+						// { dg-error "'constexpr' lambda only available with" "" { target c++14_down } .-2 }
+  auto c = [] noexcept [[deprecated]] {};	// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+						// { dg-error "parameter declaration before lambda exception specification only optional with" "" { target c++20_down } .-1 }
+  auto d = [] () [[deprecated]] {};		// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+  auto e = new int [n] [[deprecated]];		// { dg-warning "attributes ignored on outermost array type in new expression" }
+  auto e2 = new int [n] [[deprecated]] [42];	// { dg-warning "attributes ignored on outermost array type in new expression" }
+  auto f = new int [n][42] [[deprecated]];	// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+  [[deprecated]];				// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[deprecated]] {}				// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[deprecated]] if (true) {}			// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[deprecated]] while (false) {}		// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[deprecated]] goto lab;			// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[deprecated]] lab:;				// { dg-error "'deprecated' attribute ignored" }
+  [[deprecated]] try {} catch (int) {}		// { dg-warning "attributes at the beginning of statement are ignored" }
+  if ([[deprecated]] int x = 0) {}
+  switch (n)
+    {
+    [[deprecated]] case 1:			// { dg-error "'deprecated' attribute ignored" }
+    [[deprecated]] break;			// { dg-warning "attributes at the beginning of statement are ignored" }
+    [[deprecated]] default:			// { dg-error "'deprecated' attribute ignored" }
+	 break;
+    }
+  for ([[deprecated]] auto a : arr) {}
+  for ([[deprecated]] auto [a, b] : arr2) {}	// { dg-error "structured bindings only available with" "" { target c++14_down } }
+  [[deprecated]] asm ("");			// { dg-warning "attributes ignored on 'asm' declaration" }
+  try {} catch ([[deprecated]] int x) {}
+  try {} catch ([[deprecated]] int) {}
+}
+
+[[deprecated]] int bar ();
+using foobar [[deprecated]] = int;
+[[deprecated]] int a;
+[[deprecated]] auto [b, c] = arr;		// { dg-error "structured bindings only available with" "" { target c++14_down } }
+[[deprecated]];					// { dg-warning "attribute ignored" }
+inline [[deprecated]] void baz () {}		// { dg-warning "attribute ignored" }
+						// { dg-error "standard attributes in middle of decl-specifiers" "" { target *-*-* } .-1 }
+constexpr [[deprecated]] int qux () { return 0; }	// { dg-warning "attribute ignored" }
+						// { dg-error "standard attributes in middle of decl-specifiers" "" { target *-*-* } .-1 }
+int [[deprecated]] d;				// { dg-warning "attribute ignored" }
+int const [[deprecated]] e = 1;			// { dg-warning "attribute ignored" }
+struct A {} [[deprecated]];			// { dg-warning "attribute ignored in declaration of 'struct A'" }
+struct A [[deprecated]];			// { dg-warning "attribute ignored" }
+struct A [[deprecated]] a1;			// { dg-warning "attribute ignored" }
+A [[deprecated]] a2;				// { dg-warning "attribute ignored" }
+enum B { B0 } [[deprecated]];			// { dg-warning "attribute ignored in declaration of 'enum B'" }
+enum B [[deprecated]];				// { dg-warning "attribute ignored" }
+enum B [[deprecated]] b1;			// { dg-warning "attribute ignored" }
+B [[deprecated]] b2;				// { dg-warning "attribute ignored" }
+struct [[deprecated]] C {};
+int f [[deprecated]];
+int g[2] [[deprecated]];			// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+int g2 [[deprecated]] [2];
+int corge () [[deprecated]];			// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+int *[[deprecated]] h;				// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+int & [[deprecated]] i = f;			// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+						// { dg-warning "'f' is deprecated" "" { target *-*-* } .-1 }
+int && [[deprecated]] j = 0;			// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+int S::* [[deprecated]] k;			// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+auto l = sizeof (int [2] [[deprecated]]);	// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+int freddy ([[deprecated]] int a,
+	    [[deprecated]] int,
+	    [[deprecated]] int c = 0,
+	    [[deprecated]] int = 0);
+void
+corge ([[deprecated]] int a,
+       [[deprecated]] int,
+       [[deprecated]] int c = 0,
+       [[deprecated]] int = 0)
+{
+}
+[[deprecated]] void
+garply ()
+{
+}
+enum [[deprecated]] D { D0 };
+enum class [[deprecated]] E { E0 };
+enum F {};
+enum [[deprecated]] F;				// { dg-warning "type attributes ignored after type is already defined" }
+enum G {
+  G0 [[deprecated]],
+  G1 [[deprecated]] = 2
+};
+namespace [[deprecated]] H { using H0 = int; }
+namespace [[deprecated]] {}			// { dg-warning "ignoring 'deprecated' attribute on anonymous namespace" }
+[[deprecated]] using namespace H;		// { dg-warning "'deprecated' attribute directive ignored" }
+						// { dg-warning "'H' is deprecated" "" { target *-*-* } .-1 }
+struct [[deprecated]] I
+{
+  [[deprecated]];				// { dg-error "declaration does not declare anything" }
+  [[deprecated]] int i;
+  [[deprecated]] int foo ();
+  [[deprecated]] int bar () { return 1; }
+  [[deprecated]] int : 0;			// { dg-error "'deprecated' on unnamed bit-field" }
+  [[deprecated]] int i2 : 5;
+  [[deprecated]] static int i3;
+  static int i4;
+};
+[[deprecated]] int I::i4 = 0;
+struct J : [[deprecated]] C {};			// { dg-warning "attributes on base specifiers are ignored" }
+#if __cpp_concepts >= 201907L
+template <typename T>
+concept K [[deprecated]] = requires { true; };
+#endif
+typedef int L [[deprecated]];
+template <typename T>
+struct M {};
+template <>
+struct [[deprecated]] M<int> { int m; };
+typedef int N[2] [[deprecated]];		// { dg-error "'deprecated' on a type other than class or enumeration definition" }
+typedef int O [[deprecated]] [2];