C++ PATCH for c++/60364 - noreturn after first decl not diagnosed

C++ PATCH for c++/60364 - noreturn after first decl not diagnosed

[Marek Polacek]

[dcl.attr.noreturn] says "The first declaration of a function shall specify the
noreturn attribute if any declaration of that function specifies the noreturn
attribute" meaning that we should diagnose

  void func ();
  void func [[noreturn]] ();

but we do not.  I'd been meaning to issue a hard error for [[noreturn]] and
only a warning for __attribute__((noreturn)) but then I found out that we
treat [[noreturn]] exactly as the GNU attribute, and so cxx11_attribute_p
returns false for it, so I decided to make it a pedwarn for all the cases.
A pedwarn counts as a diagnostic, so we'd be conforming still.

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

2019-06-15  Marek Polacek  <polacek@redhat.com>

	PR c++/60364 - noreturn after first decl not diagnosed.
	* decl.c (duplicate_decls): Warn when the first declaration doesn't
	have noreturn but a subsequent has.

	* g++.dg/warn/noreturn-8.C: New test.

diff --git gcc/cp/decl.c gcc/cp/decl.c
index 0a3ef452536..e50873d111c 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -1922,10 +1922,23 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
 
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
-      if (merge_attr && diagnose_mismatched_attributes (olddecl, newdecl))
-	inform (olddecl_loc, DECL_INITIAL (olddecl)
-		? G_("previous definition of %qD here")
-		: G_("previous declaration of %qD here"), olddecl);
+      if (merge_attr)
+	{
+	  if (diagnose_mismatched_attributes (olddecl, newdecl))
+	    inform (olddecl_loc, DECL_INITIAL (olddecl)
+		    ? G_("previous definition of %qD here")
+		    : G_("previous declaration of %qD here"), olddecl);
+
+	  /* [dcl.attr.noreturn]: The first declaration of a function shall
+	     specify the noreturn attribute if any declaration of that function
+	     specifies the noreturn attribute.  */
+	  if (TREE_THIS_VOLATILE (newdecl)
+	      && !TREE_THIS_VOLATILE (olddecl)
+	      && pedwarn (newdecl_loc, OPT_Wpedantic, "function %qD declared "
+			  "%<noreturn%> but its first declaration was not",
+			  newdecl))
+	    inform (olddecl_loc, "previous declaration of %qD", olddecl);
+	}
 
       /* Now that functions must hold information normally held
 	 by field decls, there is extra work to do so that
diff --git gcc/testsuite/g++.dg/warn/noreturn-8.C gcc/testsuite/g++.dg/warn/noreturn-8.C
new file mode 100644
index 00000000000..d876cf9d156
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-8.C
@@ -0,0 +1,21 @@
+// PR c++/60364 - noreturn after first decl not diagnosed.
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wpedantic" }
+
+void f (); // { dg-message "previous declaration" }
+void f [[noreturn]] (); // { dg-warning "declared 'noreturn' but its first declaration was not" }
+
+void f2 (); // { dg-message "previous declaration" }
+void f2 [[gnu::noreturn]] (); // { dg-warning "declared 'noreturn' but its first declaration was not" }
+
+void f3 (); // { dg-message "previous declaration" }
+__attribute__((noreturn)) void f3 (); // { dg-warning "declared 'noreturn' but its first declaration was not" }
+
+void f4 () { __builtin_abort (); } // { dg-message "previous declaration" }
+void f4 [[noreturn]] (); // { dg-warning "declared 'noreturn' but its first declaration was not" }
+
+void f5 () { __builtin_abort (); } // { dg-message "previous declaration" }
+void f5 [[gnu::noreturn]] (); // { dg-warning "declared 'noreturn' but its first declaration was not" }
+
+void f6 () { __builtin_abort (); } // { dg-message "previous declaration" }
+__attribute__((noreturn)) void f6 (); // { dg-warning "declared 'noreturn' but its first declaration was not" }

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed

[Jakub Jelinek]

On Sat, Jun 15, 2019 at 10:29:17AM -0400, Marek Polacek wrote:
> [dcl.attr.noreturn] says "The first declaration of a function shall specify the
> noreturn attribute if any declaration of that function specifies the noreturn
> attribute" meaning that we should diagnose
> 
>   void func ();
>   void func [[noreturn]] ();
> 
> but we do not.  I'd been meaning to issue a hard error for [[noreturn]] and
> only a warning for __attribute__((noreturn)) but then I found out that we
> treat [[noreturn]] exactly as the GNU attribute, and so cxx11_attribute_p
> returns false for it, so I decided to make it a pedwarn for all the cases.
> A pedwarn counts as a diagnostic, so we'd be conforming still.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

IMHO we should treat __attribute__((noreturn)) as before without any
warnings, just [[noreturn]] that way.  There is nothing wrong on declaring
it just on second or following declaration, it is an optimization attribute.

	Jakub

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed

[Marek Polacek]

On Sat, Jun 15, 2019 at 04:33:26PM +0200, Jakub Jelinek wrote:
> On Sat, Jun 15, 2019 at 10:29:17AM -0400, Marek Polacek wrote:
> > [dcl.attr.noreturn] says "The first declaration of a function shall specify the
> > noreturn attribute if any declaration of that function specifies the noreturn
> > attribute" meaning that we should diagnose
> > 
> >   void func ();
> >   void func [[noreturn]] ();
> > 
> > but we do not.  I'd been meaning to issue a hard error for [[noreturn]] and
> > only a warning for __attribute__((noreturn)) but then I found out that we
> > treat [[noreturn]] exactly as the GNU attribute, and so cxx11_attribute_p
> > returns false for it, so I decided to make it a pedwarn for all the cases.
> > A pedwarn counts as a diagnostic, so we'd be conforming still.
> > 
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> IMHO we should treat __attribute__((noreturn)) as before without any
> warnings, just [[noreturn]] that way.  There is nothing wrong on declaring
> it just on second or following declaration, it is an optimization attribute.

That's a complication then; currently [[noreturn]], [[gnu::noreturn]], and
__attribute__((noreturn)) are not distinguishable.  :(

Guess I will really have to make the changes to treat [[noreturn]] similarly
to e.g. [[nodiscard]], so that cxx11_attribute_p works.

Thanks for pointing it out, though.

Marek

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Marek Polacek]

On Sat, Jun 15, 2019 at 10:39:13AM -0400, Marek Polacek wrote:
> On Sat, Jun 15, 2019 at 04:33:26PM +0200, Jakub Jelinek wrote:
> > On Sat, Jun 15, 2019 at 10:29:17AM -0400, Marek Polacek wrote:
> > > [dcl.attr.noreturn] says "The first declaration of a function shall specify the
> > > noreturn attribute if any declaration of that function specifies the noreturn
> > > attribute" meaning that we should diagnose
> > > 
> > >   void func ();
> > >   void func [[noreturn]] ();
> > > 
> > > but we do not.  I'd been meaning to issue a hard error for [[noreturn]] and
> > > only a warning for __attribute__((noreturn)) but then I found out that we
> > > treat [[noreturn]] exactly as the GNU attribute, and so cxx11_attribute_p
> > > returns false for it, so I decided to make it a pedwarn for all the cases.
> > > A pedwarn counts as a diagnostic, so we'd be conforming still.
> > > 
> > > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> > 
> > IMHO we should treat __attribute__((noreturn)) as before without any
> > warnings, just [[noreturn]] that way.  There is nothing wrong on declaring
> > it just on second or following declaration, it is an optimization attribute.
> 
> That's a complication then; currently [[noreturn]], [[gnu::noreturn]], and
> __attribute__((noreturn)) are not distinguishable.  :(
> 
> Guess I will really have to make the changes to treat [[noreturn]] similarly
> to e.g. [[nodiscard]], so that cxx11_attribute_p works.

Thus.  Changes I've made:
* don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
* for that I had to adjust decl_attributes, it wasn't preserving the
  C++11 form (a list in another list); fix shadowing while at it;
* the above turned up two spots that were wrongly accessing TREE_PURPOSE
  directly instead of using get_attribute_name;
* give error only for [[noreturn]] but not for __attribute__((noreturn))
  or [[gnu::noreturn]].

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

2019-06-16  Marek Polacek  <polacek@redhat.com>

	PR c++/60364 - noreturn after first decl not diagnosed.
	* attribs.c (get_attribute_namespace): No longer static.
	(decl_attributes): Avoid shadowing.  Preserve the C++11 form for C++11
	attributes.
	* attribs.h (get_attribute_namespace): Declare.
	* tree-inline.c (function_attribute_inlinable_p): Use
	get_attribute_name.

	* c-attribs.c (handle_noreturn_attribute): No longer static.
	* c-common.h (handle_noreturn_attribute): Declare.
	* c-format.c (check_function_format): Use get_attribute_name.

	* decl.c (duplicate_decls): Give an error when a function is
	declared [[noreturn]] after its first declaration.
	* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
	attribute as equivalent to GNU's.
	* tree.c (std_attribute_table): Add noreturn.

	* g++.dg/warn/noreturn-8.C: New test.

diff --git gcc/attribs.c gcc/attribs.c
index 4441922543f..8e540165597 100644
--- gcc/attribs.c
+++ gcc/attribs.c
@@ -340,7 +340,7 @@ lookup_attribute_spec (const_tree name)
    Please read the comments of cxx11_attribute_p to understand the
    format of attributes.  */
 
-static tree
+tree
 get_attribute_namespace (const_tree attr)
 {
   if (cxx11_attribute_p (attr))
@@ -469,7 +469,6 @@ tree
 decl_attributes (tree *node, tree attributes, int flags,
 		 tree last_decl /* = NULL_TREE */)
 {
-  tree a;
   tree returned_attrs = NULL_TREE;
 
   if (TREE_TYPE (*node) == error_mark_node || attributes == error_mark_node)
@@ -548,22 +547,23 @@ decl_attributes (tree *node, tree attributes, int flags,
 
   /* Note that attributes on the same declaration are not necessarily
      in the same order as in the source.  */
-  for (a = attributes; a; a = TREE_CHAIN (a))
+  for (tree attr = attributes; attr; attr = TREE_CHAIN (attr))
     {
-      tree ns = get_attribute_namespace (a);
-      tree name = get_attribute_name (a);
-      tree args = TREE_VALUE (a);
+      tree ns = get_attribute_namespace (attr);
+      tree name = get_attribute_name (attr);
+      tree args = TREE_VALUE (attr);
       tree *anode = node;
       const struct attribute_spec *spec
 	= lookup_scoped_attribute_spec (ns, name);
       int fn_ptr_quals = 0;
       tree fn_ptr_tmp = NULL_TREE;
+      const bool cxx11_attr_p = cxx11_attribute_p (attr);
 
       if (spec == NULL)
 	{
 	  if (!(flags & (int) ATTR_FLAG_BUILT_IN))
 	    {
-	      if (ns == NULL_TREE || !cxx11_attribute_p (a))
+	      if (ns == NULL_TREE || !cxx11_attr_p)
 		warning (OPT_Wattributes, "%qE attribute directive ignored",
 			 name);
 	      else
@@ -584,7 +584,7 @@ decl_attributes (tree *node, tree attributes, int flags,
       gcc_assert (is_attribute_p (spec->name, name));
 
       if (TYPE_P (*node)
-	  && cxx11_attribute_p (a)
+	  && cxx11_attr_p
 	  && !(flags & ATTR_FLAG_TYPE_IN_PLACE))
 	{
 	  /* This is a c++11 attribute that appertains to a
@@ -707,8 +707,7 @@ decl_attributes (tree *node, tree attributes, int flags,
 
       if (spec->handler != NULL)
 	{
-	  int cxx11_flag =
-	    cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
+	  int cxx11_flag = (cxx11_attr_p ? ATTR_FLAG_CXX11 : 0);
 
 	  /* Pass in an array of the current declaration followed
 	     by the last pushed/merged declaration if  one exists.
@@ -756,17 +755,23 @@ decl_attributes (tree *node, tree attributes, int flags,
 	  if (a == NULL_TREE)
 	    {
 	      /* This attribute isn't already in the list.  */
+	      tree r;
+	      /* Preserve the C++11 form.  */
+	      if (cxx11_attr_p)
+		r = tree_cons (build_tree_list (ns, name), args, old_attrs);
+	      else
+		r = tree_cons (name, args, old_attrs);
+
 	      if (DECL_P (*anode))
-		DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
+		DECL_ATTRIBUTES (*anode) = r;
 	      else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 		{
-		  TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
+		  TYPE_ATTRIBUTES (*anode) = r;
 		  /* If this is the main variant, also push the attributes
 		     out to the other variants.  */
 		  if (*anode == TYPE_MAIN_VARIANT (*anode))
 		    {
-		      tree variant;
-		      for (variant = *anode; variant;
+		      for (tree variant = *anode; variant;
 			   variant = TYPE_NEXT_VARIANT (variant))
 			{
 			  if (TYPE_ATTRIBUTES (variant) == old_attrs)
@@ -780,9 +785,7 @@ decl_attributes (tree *node, tree attributes, int flags,
 		    }
 		}
 	      else
-		*anode = build_type_attribute_variant (*anode,
-						       tree_cons (name, args,
-								  old_attrs));
+		*anode = build_type_attribute_variant (*anode, r);
 	    }
 	}
 
diff --git gcc/attribs.h gcc/attribs.h
index 83ecbbbeec9..23a7321e04a 100644
--- gcc/attribs.h
+++ gcc/attribs.h
@@ -35,6 +35,7 @@ extern tree decl_attributes (tree *, tree, int, tree = NULL_TREE);
 
 extern bool cxx11_attribute_p (const_tree);
 extern tree get_attribute_name (const_tree);
+extern tree get_attribute_namespace (const_tree);
 extern void apply_tm_attr (tree, tree);
 extern tree make_attribute (const char *, const char *, tree);
 
diff --git gcc/c-family/c-attribs.c gcc/c-family/c-attribs.c
index 7a8d3935d79..1cd95dc6665 100644
--- gcc/c-family/c-attribs.c
+++ gcc/c-family/c-attribs.c
@@ -49,7 +49,6 @@ along with GCC; see the file COPYING3.  If not see
 static tree handle_packed_attribute (tree *, tree, tree, int, bool *);
 static tree handle_nocommon_attribute (tree *, tree, tree, int, bool *);
 static tree handle_common_attribute (tree *, tree, tree, int, bool *);
-static tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 static tree handle_hot_attribute (tree *, tree, tree, int, bool *);
 static tree handle_cold_attribute (tree *, tree, tree, int, bool *);
 static tree handle_no_sanitize_attribute (tree *, tree, tree, int, bool *);
@@ -779,7 +778,7 @@ handle_common_attribute (tree *node, tree name, tree ARG_UNUSED (args),
 /* Handle a "noreturn" attribute; arguments as in
    struct attribute_spec.handler.  */
 
-static tree
+tree
 handle_noreturn_attribute (tree *node, tree name, tree ARG_UNUSED (args),
 			   int ARG_UNUSED (flags), bool *no_add_attrs)
 {
diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
index 1cf2cae6395..079225ca127 100644
--- gcc/c-family/c-common.h
+++ gcc/c-family/c-common.h
@@ -1344,6 +1344,7 @@ extern int tm_attr_to_mask (tree);
 extern tree tm_mask_to_attr (int);
 extern tree find_tm_attribute (tree);
 extern const struct attribute_spec::exclusions attr_cold_hot_exclusions[];
+extern tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 
 /* In c-format.c.  */
 extern bool valid_format_string_type_p (tree);
diff --git gcc/c-family/c-format.c gcc/c-family/c-format.c
index b10599f9982..bd9d5aeda4e 100644
--- gcc/c-family/c-format.c
+++ gcc/c-family/c-format.c
@@ -1110,7 +1110,7 @@ check_function_format (const_tree fntype, tree attrs, int nargs,
   /* See if this function has any format attributes.  */
   for (a = attrs; a; a = TREE_CHAIN (a))
     {
-      if (is_attribute_p ("format", TREE_PURPOSE (a)))
+      if (is_attribute_p ("format", get_attribute_name (a)))
 	{
 	  /* Yup; check it.  */
 	  function_format_info info;
diff --git gcc/cp/decl.c gcc/cp/decl.c
index 0a3ef452536..85f96f73739 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -1922,10 +1922,29 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
 
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
-      if (merge_attr && diagnose_mismatched_attributes (olddecl, newdecl))
-	inform (olddecl_loc, DECL_INITIAL (olddecl)
-		? G_("previous definition of %qD here")
-		: G_("previous declaration of %qD here"), olddecl);
+      if (merge_attr)
+	{
+	  if (diagnose_mismatched_attributes (olddecl, newdecl))
+	    inform (olddecl_loc, DECL_INITIAL (olddecl)
+		    ? G_("previous definition of %qD here")
+		    : G_("previous declaration of %qD here"), olddecl);
+
+	  /* [dcl.attr.noreturn]: The first declaration of a function shall
+	     specify the noreturn attribute if any declaration of that function
+	     specifies the noreturn attribute.  */
+	  tree a;
+	  if (TREE_THIS_VOLATILE (newdecl)
+	      && !TREE_THIS_VOLATILE (olddecl)
+	      /* This applies to [[noreturn]] only, not its GNU variants.  */
+	      && (a = lookup_attribute ("noreturn", DECL_ATTRIBUTES (newdecl)))
+	      && cxx11_attribute_p (a)
+	      && get_attribute_namespace (a) == NULL_TREE)
+	    {
+	      error_at (newdecl_loc, "function %qD declared %<[[noreturn]]%> "
+			"but its first declaration was not", newdecl);
+	      inform (olddecl_loc, "previous declaration of %qD", olddecl);
+	    }
+	}
 
       /* Now that functions must hold information normally held
 	 by field decls, there is extra work to do so that
diff --git gcc/cp/parser.c gcc/cp/parser.c
index 8f5ae84670a..996e54235fd 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -26121,11 +26121,11 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns)
       attr_id = canonicalize_attr_name (attr_id);
       attribute = build_tree_list (build_tree_list (NULL_TREE, attr_id),
 				   NULL_TREE);
-      /* C++11 noreturn attribute is equivalent to GNU's.  */
-      if (is_attribute_p ("noreturn", attr_id))
-	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
+      /* 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.  */
-      else if (is_attribute_p ("deprecated", attr_id))
+      if (is_attribute_p ("deprecated", attr_id))
 	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
       /* C++17 fallthrough attribute is equivalent to GNU's.  */
       else if (is_attribute_p ("fallthrough", attr_id))
diff --git gcc/cp/tree.c gcc/cp/tree.c
index cd021b7f594..bb695e14e73 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
     handle_likeliness_attribute, attr_cold_hot_exclusions },
   { "unlikely", 0, 0, false, false, false, false,
     handle_likeliness_attribute, attr_cold_hot_exclusions },
+  { "noreturn", 0, 0, true, false, false, false,
+    handle_noreturn_attribute, NULL },
   { NULL, 0, 0, false, false, false, false, NULL, NULL }
 };
 
diff --git gcc/testsuite/g++.dg/warn/noreturn-8.C gcc/testsuite/g++.dg/warn/noreturn-8.C
new file mode 100644
index 00000000000..d465468decb
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-8.C
@@ -0,0 +1,21 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wpedantic" }
+
+void f (); // { dg-message "previous declaration" }
+void f [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f2 ();
+void f2 [[gnu::noreturn]] ();
+
+void f3 ();
+__attribute__((noreturn)) void f3 ();
+
+void f4 () { __builtin_abort (); } // { dg-message "previous declaration" }
+void f4 [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f5 () { __builtin_abort (); }
+void f5 [[gnu::noreturn]] ();
+
+void f6 () { __builtin_abort (); }
+__attribute__((noreturn)) void f6 ();
diff --git gcc/tree-inline.c gcc/tree-inline.c
index 52f45a73b1d..2de5e22f10f 100644
--- gcc/tree-inline.c
+++ gcc/tree-inline.c
@@ -3899,7 +3899,7 @@ function_attribute_inlinable_p (const_tree fndecl)
 
       for (a = DECL_ATTRIBUTES (fndecl); a; a = TREE_CHAIN (a))
 	{
-	  const_tree name = TREE_PURPOSE (a);
+	  const_tree name = get_attribute_name (a);
 	  int i;
 
 	  for (i = 0; targetm.attribute_table[i].name != NULL; i++)

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Jakub Jelinek]

On Sun, Jun 16, 2019 at 12:10:37PM -0400, Marek Polacek wrote:
> > Guess I will really have to make the changes to treat [[noreturn]] similarly
> > to e.g. [[nodiscard]], so that cxx11_attribute_p works.
> 
> Thus.  Changes I've made:
> * don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
> * for that I had to adjust decl_attributes, it wasn't preserving the
>   C++11 form (a list in another list); fix shadowing while at it;
> * the above turned up two spots that were wrongly accessing TREE_PURPOSE
>   directly instead of using get_attribute_name;
> * give error only for [[noreturn]] but not for __attribute__((noreturn))
>   or [[gnu::noreturn]].
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

I'd prefer to defer review of this to Jason, just want to note that I don't
see any testsuite coverage on mixing declarations with different forms of
attributes ([[noreturn]] on one decl and __attribute__((noreturn)) or
[[gnu::noreturn]] on another one or vice versa.

	Jakub

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v3)

[Marek Polacek]

On Sun, Jun 16, 2019 at 06:18:56PM +0200, Jakub Jelinek wrote:
> On Sun, Jun 16, 2019 at 12:10:37PM -0400, Marek Polacek wrote:
> > > Guess I will really have to make the changes to treat [[noreturn]] similarly
> > > to e.g. [[nodiscard]], so that cxx11_attribute_p works.
> > 
> > Thus.  Changes I've made:
> > * don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
> > * for that I had to adjust decl_attributes, it wasn't preserving the
> >   C++11 form (a list in another list); fix shadowing while at it;
> > * the above turned up two spots that were wrongly accessing TREE_PURPOSE
> >   directly instead of using get_attribute_name;
> > * give error only for [[noreturn]] but not for __attribute__((noreturn))
> >   or [[gnu::noreturn]].
> > 
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> I'd prefer to defer review of this to Jason, just want to note that I don't
> see any testsuite coverage on mixing declarations with different forms of
> attributes ([[noreturn]] on one decl and __attribute__((noreturn)) or
> [[gnu::noreturn]] on another one or vice versa.

Added now.  I suppose it should compile fine, which it does.

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

2019-06-16  Marek Polacek  <polacek@redhat.com>

	PR c++/60364 - noreturn after first decl not diagnosed.
	* attribs.c (get_attribute_namespace): No longer static.
	(decl_attributes): Avoid shadowing.  Preserve the C++11 form for C++11
	attributes.
	* attribs.h (get_attribute_namespace): Declare.
	* tree-inline.c (function_attribute_inlinable_p): Use
	get_attribute_name.

	* c-attribs.c (handle_noreturn_attribute): No longer static.
	* c-common.h (handle_noreturn_attribute): Declare.
	* c-format.c (check_function_format): Use get_attribute_name.

	* decl.c (duplicate_decls): Give an error when a function is
	declared [[noreturn]] after its first declaration.
	* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
	attribute as equivalent to GNU's.
	* tree.c (std_attribute_table): Add noreturn.

	* g++.dg/warn/noreturn-8.C: New test.
	* g++.dg/warn/noreturn-9.C: New test.

diff --git gcc/attribs.c gcc/attribs.c
index 4441922543f..8e540165597 100644
--- gcc/attribs.c
+++ gcc/attribs.c
@@ -340,7 +340,7 @@ lookup_attribute_spec (const_tree name)
    Please read the comments of cxx11_attribute_p to understand the
    format of attributes.  */
 
-static tree
+tree
 get_attribute_namespace (const_tree attr)
 {
   if (cxx11_attribute_p (attr))
@@ -469,7 +469,6 @@ tree
 decl_attributes (tree *node, tree attributes, int flags,
 		 tree last_decl /* = NULL_TREE */)
 {
-  tree a;
   tree returned_attrs = NULL_TREE;
 
   if (TREE_TYPE (*node) == error_mark_node || attributes == error_mark_node)
@@ -548,22 +547,23 @@ decl_attributes (tree *node, tree attributes, int flags,
 
   /* Note that attributes on the same declaration are not necessarily
      in the same order as in the source.  */
-  for (a = attributes; a; a = TREE_CHAIN (a))
+  for (tree attr = attributes; attr; attr = TREE_CHAIN (attr))
     {
-      tree ns = get_attribute_namespace (a);
-      tree name = get_attribute_name (a);
-      tree args = TREE_VALUE (a);
+      tree ns = get_attribute_namespace (attr);
+      tree name = get_attribute_name (attr);
+      tree args = TREE_VALUE (attr);
       tree *anode = node;
       const struct attribute_spec *spec
 	= lookup_scoped_attribute_spec (ns, name);
       int fn_ptr_quals = 0;
       tree fn_ptr_tmp = NULL_TREE;
+      const bool cxx11_attr_p = cxx11_attribute_p (attr);
 
       if (spec == NULL)
 	{
 	  if (!(flags & (int) ATTR_FLAG_BUILT_IN))
 	    {
-	      if (ns == NULL_TREE || !cxx11_attribute_p (a))
+	      if (ns == NULL_TREE || !cxx11_attr_p)
 		warning (OPT_Wattributes, "%qE attribute directive ignored",
 			 name);
 	      else
@@ -584,7 +584,7 @@ decl_attributes (tree *node, tree attributes, int flags,
       gcc_assert (is_attribute_p (spec->name, name));
 
       if (TYPE_P (*node)
-	  && cxx11_attribute_p (a)
+	  && cxx11_attr_p
 	  && !(flags & ATTR_FLAG_TYPE_IN_PLACE))
 	{
 	  /* This is a c++11 attribute that appertains to a
@@ -707,8 +707,7 @@ decl_attributes (tree *node, tree attributes, int flags,
 
       if (spec->handler != NULL)
 	{
-	  int cxx11_flag =
-	    cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
+	  int cxx11_flag = (cxx11_attr_p ? ATTR_FLAG_CXX11 : 0);
 
 	  /* Pass in an array of the current declaration followed
 	     by the last pushed/merged declaration if  one exists.
@@ -756,17 +755,23 @@ decl_attributes (tree *node, tree attributes, int flags,
 	  if (a == NULL_TREE)
 	    {
 	      /* This attribute isn't already in the list.  */
+	      tree r;
+	      /* Preserve the C++11 form.  */
+	      if (cxx11_attr_p)
+		r = tree_cons (build_tree_list (ns, name), args, old_attrs);
+	      else
+		r = tree_cons (name, args, old_attrs);
+
 	      if (DECL_P (*anode))
-		DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
+		DECL_ATTRIBUTES (*anode) = r;
 	      else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 		{
-		  TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
+		  TYPE_ATTRIBUTES (*anode) = r;
 		  /* If this is the main variant, also push the attributes
 		     out to the other variants.  */
 		  if (*anode == TYPE_MAIN_VARIANT (*anode))
 		    {
-		      tree variant;
-		      for (variant = *anode; variant;
+		      for (tree variant = *anode; variant;
 			   variant = TYPE_NEXT_VARIANT (variant))
 			{
 			  if (TYPE_ATTRIBUTES (variant) == old_attrs)
@@ -780,9 +785,7 @@ decl_attributes (tree *node, tree attributes, int flags,
 		    }
 		}
 	      else
-		*anode = build_type_attribute_variant (*anode,
-						       tree_cons (name, args,
-								  old_attrs));
+		*anode = build_type_attribute_variant (*anode, r);
 	    }
 	}
 
diff --git gcc/attribs.h gcc/attribs.h
index 83ecbbbeec9..23a7321e04a 100644
--- gcc/attribs.h
+++ gcc/attribs.h
@@ -35,6 +35,7 @@ extern tree decl_attributes (tree *, tree, int, tree = NULL_TREE);
 
 extern bool cxx11_attribute_p (const_tree);
 extern tree get_attribute_name (const_tree);
+extern tree get_attribute_namespace (const_tree);
 extern void apply_tm_attr (tree, tree);
 extern tree make_attribute (const char *, const char *, tree);
 
diff --git gcc/c-family/c-attribs.c gcc/c-family/c-attribs.c
index 7a8d3935d79..1cd95dc6665 100644
--- gcc/c-family/c-attribs.c
+++ gcc/c-family/c-attribs.c
@@ -49,7 +49,6 @@ along with GCC; see the file COPYING3.  If not see
 static tree handle_packed_attribute (tree *, tree, tree, int, bool *);
 static tree handle_nocommon_attribute (tree *, tree, tree, int, bool *);
 static tree handle_common_attribute (tree *, tree, tree, int, bool *);
-static tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 static tree handle_hot_attribute (tree *, tree, tree, int, bool *);
 static tree handle_cold_attribute (tree *, tree, tree, int, bool *);
 static tree handle_no_sanitize_attribute (tree *, tree, tree, int, bool *);
@@ -779,7 +778,7 @@ handle_common_attribute (tree *node, tree name, tree ARG_UNUSED (args),
 /* Handle a "noreturn" attribute; arguments as in
    struct attribute_spec.handler.  */
 
-static tree
+tree
 handle_noreturn_attribute (tree *node, tree name, tree ARG_UNUSED (args),
 			   int ARG_UNUSED (flags), bool *no_add_attrs)
 {
diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
index 1cf2cae6395..079225ca127 100644
--- gcc/c-family/c-common.h
+++ gcc/c-family/c-common.h
@@ -1344,6 +1344,7 @@ extern int tm_attr_to_mask (tree);
 extern tree tm_mask_to_attr (int);
 extern tree find_tm_attribute (tree);
 extern const struct attribute_spec::exclusions attr_cold_hot_exclusions[];
+extern tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 
 /* In c-format.c.  */
 extern bool valid_format_string_type_p (tree);
diff --git gcc/c-family/c-format.c gcc/c-family/c-format.c
index b10599f9982..bd9d5aeda4e 100644
--- gcc/c-family/c-format.c
+++ gcc/c-family/c-format.c
@@ -1110,7 +1110,7 @@ check_function_format (const_tree fntype, tree attrs, int nargs,
   /* See if this function has any format attributes.  */
   for (a = attrs; a; a = TREE_CHAIN (a))
     {
-      if (is_attribute_p ("format", TREE_PURPOSE (a)))
+      if (is_attribute_p ("format", get_attribute_name (a)))
 	{
 	  /* Yup; check it.  */
 	  function_format_info info;
diff --git gcc/cp/decl.c gcc/cp/decl.c
index 0a3ef452536..85f96f73739 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -1922,10 +1922,29 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
 
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
-      if (merge_attr && diagnose_mismatched_attributes (olddecl, newdecl))
-	inform (olddecl_loc, DECL_INITIAL (olddecl)
-		? G_("previous definition of %qD here")
-		: G_("previous declaration of %qD here"), olddecl);
+      if (merge_attr)
+	{
+	  if (diagnose_mismatched_attributes (olddecl, newdecl))
+	    inform (olddecl_loc, DECL_INITIAL (olddecl)
+		    ? G_("previous definition of %qD here")
+		    : G_("previous declaration of %qD here"), olddecl);
+
+	  /* [dcl.attr.noreturn]: The first declaration of a function shall
+	     specify the noreturn attribute if any declaration of that function
+	     specifies the noreturn attribute.  */
+	  tree a;
+	  if (TREE_THIS_VOLATILE (newdecl)
+	      && !TREE_THIS_VOLATILE (olddecl)
+	      /* This applies to [[noreturn]] only, not its GNU variants.  */
+	      && (a = lookup_attribute ("noreturn", DECL_ATTRIBUTES (newdecl)))
+	      && cxx11_attribute_p (a)
+	      && get_attribute_namespace (a) == NULL_TREE)
+	    {
+	      error_at (newdecl_loc, "function %qD declared %<[[noreturn]]%> "
+			"but its first declaration was not", newdecl);
+	      inform (olddecl_loc, "previous declaration of %qD", olddecl);
+	    }
+	}
 
       /* Now that functions must hold information normally held
 	 by field decls, there is extra work to do so that
diff --git gcc/cp/parser.c gcc/cp/parser.c
index 8f5ae84670a..996e54235fd 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -26121,11 +26121,11 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns)
       attr_id = canonicalize_attr_name (attr_id);
       attribute = build_tree_list (build_tree_list (NULL_TREE, attr_id),
 				   NULL_TREE);
-      /* C++11 noreturn attribute is equivalent to GNU's.  */
-      if (is_attribute_p ("noreturn", attr_id))
-	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
+      /* 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.  */
-      else if (is_attribute_p ("deprecated", attr_id))
+      if (is_attribute_p ("deprecated", attr_id))
 	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
       /* C++17 fallthrough attribute is equivalent to GNU's.  */
       else if (is_attribute_p ("fallthrough", attr_id))
diff --git gcc/cp/tree.c gcc/cp/tree.c
index cd021b7f594..bb695e14e73 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
     handle_likeliness_attribute, attr_cold_hot_exclusions },
   { "unlikely", 0, 0, false, false, false, false,
     handle_likeliness_attribute, attr_cold_hot_exclusions },
+  { "noreturn", 0, 0, true, false, false, false,
+    handle_noreturn_attribute, NULL },
   { NULL, 0, 0, false, false, false, false, NULL, NULL }
 };
 
diff --git gcc/testsuite/g++.dg/warn/noreturn-8.C gcc/testsuite/g++.dg/warn/noreturn-8.C
new file mode 100644
index 00000000000..d465468decb
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-8.C
@@ -0,0 +1,21 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wpedantic" }
+
+void f (); // { dg-message "previous declaration" }
+void f [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f2 ();
+void f2 [[gnu::noreturn]] ();
+
+void f3 ();
+__attribute__((noreturn)) void f3 ();
+
+void f4 () { __builtin_abort (); } // { dg-message "previous declaration" }
+void f4 [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f5 () { __builtin_abort (); }
+void f5 [[gnu::noreturn]] ();
+
+void f6 () { __builtin_abort (); }
+__attribute__((noreturn)) void f6 ();
diff --git gcc/testsuite/g++.dg/warn/noreturn-9.C gcc/testsuite/g++.dg/warn/noreturn-9.C
new file mode 100644
index 00000000000..f7ede57aab0
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-9.C
@@ -0,0 +1,21 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wpedantic" }
+
+void f1 [[gnu::noreturn]] ();
+void f1 [[noreturn]] ();
+
+void f2 [[noreturn]] ();
+void f2 [[gnu::noreturn]] ();
+
+__attribute__((noreturn)) void f3 ();
+void f3 [[noreturn]] ();
+
+void f4 [[noreturn]] ();
+__attribute__((noreturn)) void f4 ();
+
+__attribute__((noreturn)) void f5 ();
+void f5 [[gnu::noreturn]] ();
+
+void f6 [[gnu::noreturn]] ();
+__attribute__((noreturn)) void f6 ();
diff --git gcc/tree-inline.c gcc/tree-inline.c
index 52f45a73b1d..2de5e22f10f 100644
--- gcc/tree-inline.c
+++ gcc/tree-inline.c
@@ -3899,7 +3899,7 @@ function_attribute_inlinable_p (const_tree fndecl)
 
       for (a = DECL_ATTRIBUTES (fndecl); a; a = TREE_CHAIN (a))
 	{
-	  const_tree name = TREE_PURPOSE (a);
+	  const_tree name = get_attribute_name (a);
 	  int i;
 
 	  for (i = 0; targetm.attribute_table[i].name != NULL; i++)

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Martin Sebor]

On 6/16/19 10:10 AM, Marek Polacek wrote:
> On Sat, Jun 15, 2019 at 10:39:13AM -0400, Marek Polacek wrote:
>> On Sat, Jun 15, 2019 at 04:33:26PM +0200, Jakub Jelinek wrote:
>>> On Sat, Jun 15, 2019 at 10:29:17AM -0400, Marek Polacek wrote:
>>>> [dcl.attr.noreturn] says "The first declaration of a function shall specify the
>>>> noreturn attribute if any declaration of that function specifies the noreturn
>>>> attribute" meaning that we should diagnose
>>>>
>>>>    void func ();
>>>>    void func [[noreturn]] ();
>>>>
>>>> but we do not.  I'd been meaning to issue a hard error for [[noreturn]] and
>>>> only a warning for __attribute__((noreturn)) but then I found out that we
>>>> treat [[noreturn]] exactly as the GNU attribute, and so cxx11_attribute_p
>>>> returns false for it, so I decided to make it a pedwarn for all the cases.
>>>> A pedwarn counts as a diagnostic, so we'd be conforming still.
>>>>
>>>> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>>>
>>> IMHO we should treat __attribute__((noreturn)) as before without any
>>> warnings, just [[noreturn]] that way.  There is nothing wrong on declaring
>>> it just on second or following declaration, it is an optimization attribute.
>>
>> That's a complication then; currently [[noreturn]], [[gnu::noreturn]], and
>> __attribute__((noreturn)) are not distinguishable.  :(
>>
>> Guess I will really have to make the changes to treat [[noreturn]] similarly
>> to e.g. [[nodiscard]], so that cxx11_attribute_p works.
> 
> Thus.  Changes I've made:
> * don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
> * for that I had to adjust decl_attributes, it wasn't preserving the
>    C++11 form (a list in another list); fix shadowing while at it;
> * the above turned up two spots that were wrongly accessing TREE_PURPOSE
>    directly instead of using get_attribute_name;
> * give error only for [[noreturn]] but not for __attribute__((noreturn))
>    or [[gnu::noreturn]].
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> 2019-06-16  Marek Polacek  <polacek@redhat.com>
> 
> 	PR c++/60364 - noreturn after first decl not diagnosed.
> 	* attribs.c (get_attribute_namespace): No longer static.
> 	(decl_attributes): Avoid shadowing.  Preserve the C++11 form for C++11
> 	attributes.
> 	* attribs.h (get_attribute_namespace): Declare.
> 	* tree-inline.c (function_attribute_inlinable_p): Use
> 	get_attribute_name.
> 
> 	* c-attribs.c (handle_noreturn_attribute): No longer static.
> 	* c-common.h (handle_noreturn_attribute): Declare.
> 	* c-format.c (check_function_format): Use get_attribute_name.
> 
> 	* decl.c (duplicate_decls): Give an error when a function is
> 	declared [[noreturn]] after its first declaration.
> 	* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
> 	attribute as equivalent to GNU's.
> 	* tree.c (std_attribute_table): Add noreturn.
> 
> 	* g++.dg/warn/noreturn-8.C: New test.
...
> diff --git gcc/cp/tree.c gcc/cp/tree.c
> index cd021b7f594..bb695e14e73 100644
> --- gcc/cp/tree.c
> +++ gcc/cp/tree.c
> @@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
>       handle_likeliness_attribute, attr_cold_hot_exclusions },
>     { "unlikely", 0, 0, false, false, false, false,
>       handle_likeliness_attribute, attr_cold_hot_exclusions },
> +  { "noreturn", 0, 0, true, false, false, false,
> +    handle_noreturn_attribute, NULL },
                                   ^^^^

The GNU attribute is made mutually exclusive with a bunch of other
attributes (e.g., malloc or warn_unused_result) by setting the last
member to the array of exclusive attribute.  Does the change preserve
this relationship some other way?

Martin

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v3)

[Jakub Jelinek]

On Sun, Jun 16, 2019 at 12:36:58PM -0400, Marek Polacek wrote:
> On Sun, Jun 16, 2019 at 06:18:56PM +0200, Jakub Jelinek wrote:
> > On Sun, Jun 16, 2019 at 12:10:37PM -0400, Marek Polacek wrote:
> > > > Guess I will really have to make the changes to treat [[noreturn]] similarly
> > > > to e.g. [[nodiscard]], so that cxx11_attribute_p works.
> > > 
> > > Thus.  Changes I've made:
> > > * don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
> > > * for that I had to adjust decl_attributes, it wasn't preserving the
> > >   C++11 form (a list in another list); fix shadowing while at it;
> > > * the above turned up two spots that were wrongly accessing TREE_PURPOSE
> > >   directly instead of using get_attribute_name;
> > > * give error only for [[noreturn]] but not for __attribute__((noreturn))
> > >   or [[gnu::noreturn]].
> > > 
> > > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> > 
> > I'd prefer to defer review of this to Jason, just want to note that I don't
> > see any testsuite coverage on mixing declarations with different forms of
> > attributes ([[noreturn]] on one decl and __attribute__((noreturn)) or
> > [[gnu::noreturn]] on another one or vice versa.
> 
> Added now.  I suppose it should compile fine, which it does.

I meant also the tests of the new diagnostics, say if you have
a decl without any of those attributes, then gnu:: one (or __attribute__
one; that merge decls should be ok) and on third decl [[noreturn]] (shall
that diagnose anything or not?  As there is no way to differentiate it from
the gnu:: attribute on the very first one, I'd say it shouldn't, with the
use of the gnu:: or __attribute__ we are already outside of the standard.

	Jakub

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Marek Polacek]

On Mon, Jun 17, 2019 at 09:02:17AM -0600, Martin Sebor wrote:
> > diff --git gcc/cp/tree.c gcc/cp/tree.c
> > index cd021b7f594..bb695e14e73 100644
> > --- gcc/cp/tree.c
> > +++ gcc/cp/tree.c
> > @@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
> >       handle_likeliness_attribute, attr_cold_hot_exclusions },
> >     { "unlikely", 0, 0, false, false, false, false,
> >       handle_likeliness_attribute, attr_cold_hot_exclusions },
> > +  { "noreturn", 0, 0, true, false, false, false,
> > +    handle_noreturn_attribute, NULL },
>                                   ^^^^
> 
> The GNU attribute is made mutually exclusive with a bunch of other
> attributes (e.g., malloc or warn_unused_result) by setting the last
> member to the array of exclusive attribute.  Does the change preserve
> this relationship some other way?

Oop, no, that is a bug.  I meant to go back to that, but I'd forgotten to add
an XXX comment as I'm wont to, and the testsuite doesn't test that, so it
slipped.  Fixed & new test added.  Thanks for catching it.

Also added a test for the scenario Jakub pointed out in the other mail.

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

2019-06-17  Marek Polacek  <polacek@redhat.com>

	PR c++/60364 - noreturn after first decl not diagnosed.
	* attribs.c (get_attribute_namespace): No longer static.
	(decl_attributes): Avoid shadowing.  Preserve the C++11 form for C++11
	attributes.
	(attr_noreturn_exclusions): Make it extern.
	* attribs.h (get_attribute_namespace): Declare.
	* tree-inline.c (function_attribute_inlinable_p): Use
	get_attribute_name.

	* c-attribs.c (handle_noreturn_attribute): No longer static.
	* c-common.h (handle_noreturn_attribute, attr_noreturn_exclusions):
	Declare.
	* c-format.c (check_function_format): Use get_attribute_name.

	* decl.c (duplicate_decls): Give an error when a function is
	declared [[noreturn]] after its first declaration.
	* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
	attribute as equivalent to GNU's.
	* tree.c (std_attribute_table): Add noreturn.

	* g++.dg/warn/noreturn-8.C: New test.
	* g++.dg/warn/noreturn-9.C: New test.
	* g++.dg/warn/noreturn-10.C: New test.
	* g++.dg/warn/noreturn-11.C: New test.

diff --git gcc/attribs.c gcc/attribs.c
index 4441922543f..8e540165597 100644
--- gcc/attribs.c
+++ gcc/attribs.c
@@ -340,7 +340,7 @@ lookup_attribute_spec (const_tree name)
    Please read the comments of cxx11_attribute_p to understand the
    format of attributes.  */
 
-static tree
+tree
 get_attribute_namespace (const_tree attr)
 {
   if (cxx11_attribute_p (attr))
@@ -469,7 +469,6 @@ tree
 decl_attributes (tree *node, tree attributes, int flags,
 		 tree last_decl /* = NULL_TREE */)
 {
-  tree a;
   tree returned_attrs = NULL_TREE;
 
   if (TREE_TYPE (*node) == error_mark_node || attributes == error_mark_node)
@@ -548,22 +547,23 @@ decl_attributes (tree *node, tree attributes, int flags,
 
   /* Note that attributes on the same declaration are not necessarily
      in the same order as in the source.  */
-  for (a = attributes; a; a = TREE_CHAIN (a))
+  for (tree attr = attributes; attr; attr = TREE_CHAIN (attr))
     {
-      tree ns = get_attribute_namespace (a);
-      tree name = get_attribute_name (a);
-      tree args = TREE_VALUE (a);
+      tree ns = get_attribute_namespace (attr);
+      tree name = get_attribute_name (attr);
+      tree args = TREE_VALUE (attr);
       tree *anode = node;
       const struct attribute_spec *spec
 	= lookup_scoped_attribute_spec (ns, name);
       int fn_ptr_quals = 0;
       tree fn_ptr_tmp = NULL_TREE;
+      const bool cxx11_attr_p = cxx11_attribute_p (attr);
 
       if (spec == NULL)
 	{
 	  if (!(flags & (int) ATTR_FLAG_BUILT_IN))
 	    {
-	      if (ns == NULL_TREE || !cxx11_attribute_p (a))
+	      if (ns == NULL_TREE || !cxx11_attr_p)
 		warning (OPT_Wattributes, "%qE attribute directive ignored",
 			 name);
 	      else
@@ -584,7 +584,7 @@ decl_attributes (tree *node, tree attributes, int flags,
       gcc_assert (is_attribute_p (spec->name, name));
 
       if (TYPE_P (*node)
-	  && cxx11_attribute_p (a)
+	  && cxx11_attr_p
 	  && !(flags & ATTR_FLAG_TYPE_IN_PLACE))
 	{
 	  /* This is a c++11 attribute that appertains to a
@@ -707,8 +707,7 @@ decl_attributes (tree *node, tree attributes, int flags,
 
       if (spec->handler != NULL)
 	{
-	  int cxx11_flag =
-	    cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
+	  int cxx11_flag = (cxx11_attr_p ? ATTR_FLAG_CXX11 : 0);
 
 	  /* Pass in an array of the current declaration followed
 	     by the last pushed/merged declaration if  one exists.
@@ -756,17 +755,23 @@ decl_attributes (tree *node, tree attributes, int flags,
 	  if (a == NULL_TREE)
 	    {
 	      /* This attribute isn't already in the list.  */
+	      tree r;
+	      /* Preserve the C++11 form.  */
+	      if (cxx11_attr_p)
+		r = tree_cons (build_tree_list (ns, name), args, old_attrs);
+	      else
+		r = tree_cons (name, args, old_attrs);
+
 	      if (DECL_P (*anode))
-		DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
+		DECL_ATTRIBUTES (*anode) = r;
 	      else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 		{
-		  TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
+		  TYPE_ATTRIBUTES (*anode) = r;
 		  /* If this is the main variant, also push the attributes
 		     out to the other variants.  */
 		  if (*anode == TYPE_MAIN_VARIANT (*anode))
 		    {
-		      tree variant;
-		      for (variant = *anode; variant;
+		      for (tree variant = *anode; variant;
 			   variant = TYPE_NEXT_VARIANT (variant))
 			{
 			  if (TYPE_ATTRIBUTES (variant) == old_attrs)
@@ -780,9 +785,7 @@ decl_attributes (tree *node, tree attributes, int flags,
 		    }
 		}
 	      else
-		*anode = build_type_attribute_variant (*anode,
-						       tree_cons (name, args,
-								  old_attrs));
+		*anode = build_type_attribute_variant (*anode, r);
 	    }
 	}
 
diff --git gcc/attribs.h gcc/attribs.h
index 83ecbbbeec9..23a7321e04a 100644
--- gcc/attribs.h
+++ gcc/attribs.h
@@ -35,6 +35,7 @@ extern tree decl_attributes (tree *, tree, int, tree = NULL_TREE);
 
 extern bool cxx11_attribute_p (const_tree);
 extern tree get_attribute_name (const_tree);
+extern tree get_attribute_namespace (const_tree);
 extern void apply_tm_attr (tree, tree);
 extern tree make_attribute (const char *, const char *, tree);
 
diff --git gcc/c-family/c-attribs.c gcc/c-family/c-attribs.c
index 7a8d3935d79..48819e74e5b 100644
--- gcc/c-family/c-attribs.c
+++ gcc/c-family/c-attribs.c
@@ -49,7 +49,6 @@ along with GCC; see the file COPYING3.  If not see
 static tree handle_packed_attribute (tree *, tree, tree, int, bool *);
 static tree handle_nocommon_attribute (tree *, tree, tree, int, bool *);
 static tree handle_common_attribute (tree *, tree, tree, int, bool *);
-static tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 static tree handle_hot_attribute (tree *, tree, tree, int, bool *);
 static tree handle_cold_attribute (tree *, tree, tree, int, bool *);
 static tree handle_no_sanitize_attribute (tree *, tree, tree, int, bool *);
@@ -190,7 +189,7 @@ static const struct attribute_spec::exclusions attr_noinline_exclusions[] =
   ATTR_EXCL (NULL, false, false, false),
 };
 
-static const struct attribute_spec::exclusions attr_noreturn_exclusions[] =
+extern const struct attribute_spec::exclusions attr_noreturn_exclusions[] =
 {
   ATTR_EXCL ("alloc_align", true, true, true),
   ATTR_EXCL ("alloc_size", true, true, true),
@@ -779,7 +778,7 @@ handle_common_attribute (tree *node, tree name, tree ARG_UNUSED (args),
 /* Handle a "noreturn" attribute; arguments as in
    struct attribute_spec.handler.  */
 
-static tree
+tree
 handle_noreturn_attribute (tree *node, tree name, tree ARG_UNUSED (args),
 			   int ARG_UNUSED (flags), bool *no_add_attrs)
 {
diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
index 1cf2cae6395..5ac6e5eacf9 100644
--- gcc/c-family/c-common.h
+++ gcc/c-family/c-common.h
@@ -1344,6 +1344,8 @@ extern int tm_attr_to_mask (tree);
 extern tree tm_mask_to_attr (int);
 extern tree find_tm_attribute (tree);
 extern const struct attribute_spec::exclusions attr_cold_hot_exclusions[];
+extern const struct attribute_spec::exclusions attr_noreturn_exclusions[];
+extern tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 
 /* In c-format.c.  */
 extern bool valid_format_string_type_p (tree);
diff --git gcc/c-family/c-format.c gcc/c-family/c-format.c
index b10599f9982..bd9d5aeda4e 100644
--- gcc/c-family/c-format.c
+++ gcc/c-family/c-format.c
@@ -1110,7 +1110,7 @@ check_function_format (const_tree fntype, tree attrs, int nargs,
   /* See if this function has any format attributes.  */
   for (a = attrs; a; a = TREE_CHAIN (a))
     {
-      if (is_attribute_p ("format", TREE_PURPOSE (a)))
+      if (is_attribute_p ("format", get_attribute_name (a)))
 	{
 	  /* Yup; check it.  */
 	  function_format_info info;
diff --git gcc/cp/decl.c gcc/cp/decl.c
index 0a3ef452536..85f96f73739 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -1922,10 +1922,29 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
 
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
-      if (merge_attr && diagnose_mismatched_attributes (olddecl, newdecl))
-	inform (olddecl_loc, DECL_INITIAL (olddecl)
-		? G_("previous definition of %qD here")
-		: G_("previous declaration of %qD here"), olddecl);
+      if (merge_attr)
+	{
+	  if (diagnose_mismatched_attributes (olddecl, newdecl))
+	    inform (olddecl_loc, DECL_INITIAL (olddecl)
+		    ? G_("previous definition of %qD here")
+		    : G_("previous declaration of %qD here"), olddecl);
+
+	  /* [dcl.attr.noreturn]: The first declaration of a function shall
+	     specify the noreturn attribute if any declaration of that function
+	     specifies the noreturn attribute.  */
+	  tree a;
+	  if (TREE_THIS_VOLATILE (newdecl)
+	      && !TREE_THIS_VOLATILE (olddecl)
+	      /* This applies to [[noreturn]] only, not its GNU variants.  */
+	      && (a = lookup_attribute ("noreturn", DECL_ATTRIBUTES (newdecl)))
+	      && cxx11_attribute_p (a)
+	      && get_attribute_namespace (a) == NULL_TREE)
+	    {
+	      error_at (newdecl_loc, "function %qD declared %<[[noreturn]]%> "
+			"but its first declaration was not", newdecl);
+	      inform (olddecl_loc, "previous declaration of %qD", olddecl);
+	    }
+	}
 
       /* Now that functions must hold information normally held
 	 by field decls, there is extra work to do so that
diff --git gcc/cp/parser.c gcc/cp/parser.c
index 8f5ae84670a..996e54235fd 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -26121,11 +26121,11 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns)
       attr_id = canonicalize_attr_name (attr_id);
       attribute = build_tree_list (build_tree_list (NULL_TREE, attr_id),
 				   NULL_TREE);
-      /* C++11 noreturn attribute is equivalent to GNU's.  */
-      if (is_attribute_p ("noreturn", attr_id))
-	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
+      /* 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.  */
-      else if (is_attribute_p ("deprecated", attr_id))
+      if (is_attribute_p ("deprecated", attr_id))
 	TREE_PURPOSE (TREE_PURPOSE (attribute)) = gnu_identifier;
       /* C++17 fallthrough attribute is equivalent to GNU's.  */
       else if (is_attribute_p ("fallthrough", attr_id))
diff --git gcc/cp/tree.c gcc/cp/tree.c
index cd021b7f594..978aea56193 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
     handle_likeliness_attribute, attr_cold_hot_exclusions },
   { "unlikely", 0, 0, false, false, false, false,
     handle_likeliness_attribute, attr_cold_hot_exclusions },
+  { "noreturn", 0, 0, true, false, false, false,
+    handle_noreturn_attribute, attr_noreturn_exclusions },
   { NULL, 0, 0, false, false, false, false, NULL, NULL }
 };
 
diff --git gcc/testsuite/g++.dg/warn/noreturn-10.C gcc/testsuite/g++.dg/warn/noreturn-10.C
new file mode 100644
index 00000000000..6f7df48bf18
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-10.C
@@ -0,0 +1,10 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+
+void* fn1 [[gnu::returns_twice, noreturn]] (); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'returns_twice'" }
+void* fn2 [[gnu::alloc_align(1), noreturn]] (int); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'alloc_align'" }
+void* fn3 [[gnu::alloc_size(1), noreturn]] (int); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'alloc_size'" }
+void* fn4 [[gnu::const, noreturn]] (); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'const'" }
+void* fn5 [[gnu::malloc, noreturn]] (int); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'malloc'" }
+void* fn6 [[gnu::pure, noreturn]] (); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'pure'" }
+void* fn7 [[gnu::warn_unused_result, noreturn]] (); // { dg-warning "ignoring attribute 'noreturn' because it conflicts with attribute 'warn_unused_result'" }
diff --git gcc/testsuite/g++.dg/warn/noreturn-11.C gcc/testsuite/g++.dg/warn/noreturn-11.C
new file mode 100644
index 00000000000..e0265eba701
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-11.C
@@ -0,0 +1,25 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+
+void f1 ();
+void f1 [[gnu::noreturn]] ();
+void f1 [[noreturn]] ();
+
+void f2 ();
+__attribute__((noreturn)) void f2 ();
+void f2 [[noreturn]] ();
+
+void f3 ();
+void f3 [[gnu::noreturn]] ();
+void f3 ();
+void f3 [[noreturn]] ();
+
+void f4 ();
+void f4 ();
+void f4 ();
+void f4 [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f5 [[noreturn]] ();
+void f5 ();
+void f5 ();
+void f5 [[noreturn]] ();
diff --git gcc/testsuite/g++.dg/warn/noreturn-8.C gcc/testsuite/g++.dg/warn/noreturn-8.C
new file mode 100644
index 00000000000..d465468decb
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-8.C
@@ -0,0 +1,21 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wpedantic" }
+
+void f (); // { dg-message "previous declaration" }
+void f [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f2 ();
+void f2 [[gnu::noreturn]] ();
+
+void f3 ();
+__attribute__((noreturn)) void f3 ();
+
+void f4 () { __builtin_abort (); } // { dg-message "previous declaration" }
+void f4 [[noreturn]] (); // { dg-error "declared '\\\[\\\[noreturn\\\]\\\]' but its first declaration was not" }
+
+void f5 () { __builtin_abort (); }
+void f5 [[gnu::noreturn]] ();
+
+void f6 () { __builtin_abort (); }
+__attribute__((noreturn)) void f6 ();
diff --git gcc/testsuite/g++.dg/warn/noreturn-9.C gcc/testsuite/g++.dg/warn/noreturn-9.C
new file mode 100644
index 00000000000..f7ede57aab0
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/noreturn-9.C
@@ -0,0 +1,21 @@
+// PR c++/60364
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wpedantic" }
+
+void f1 [[gnu::noreturn]] ();
+void f1 [[noreturn]] ();
+
+void f2 [[noreturn]] ();
+void f2 [[gnu::noreturn]] ();
+
+__attribute__((noreturn)) void f3 ();
+void f3 [[noreturn]] ();
+
+void f4 [[noreturn]] ();
+__attribute__((noreturn)) void f4 ();
+
+__attribute__((noreturn)) void f5 ();
+void f5 [[gnu::noreturn]] ();
+
+void f6 [[gnu::noreturn]] ();
+__attribute__((noreturn)) void f6 ();
diff --git gcc/tree-inline.c gcc/tree-inline.c
index 52f45a73b1d..2de5e22f10f 100644
--- gcc/tree-inline.c
+++ gcc/tree-inline.c
@@ -3899,7 +3899,7 @@ function_attribute_inlinable_p (const_tree fndecl)
 
       for (a = DECL_ATTRIBUTES (fndecl); a; a = TREE_CHAIN (a))
 	{
-	  const_tree name = TREE_PURPOSE (a);
+	  const_tree name = get_attribute_name (a);
 	  int i;
 
 	  for (i = 0; targetm.attribute_table[i].name != NULL; i++)

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v3)

[Marek Polacek]

On Mon, Jun 17, 2019 at 05:48:23PM +0200, Jakub Jelinek wrote:
> On Sun, Jun 16, 2019 at 12:36:58PM -0400, Marek Polacek wrote:
> > On Sun, Jun 16, 2019 at 06:18:56PM +0200, Jakub Jelinek wrote:
> > > On Sun, Jun 16, 2019 at 12:10:37PM -0400, Marek Polacek wrote:
> > > > > Guess I will really have to make the changes to treat [[noreturn]] similarly
> > > > > to e.g. [[nodiscard]], so that cxx11_attribute_p works.
> > > > 
> > > > Thus.  Changes I've made:
> > > > * don't treat [[noreturn]] as an equivalent to __attribute__((noreturn));
> > > > * for that I had to adjust decl_attributes, it wasn't preserving the
> > > >   C++11 form (a list in another list); fix shadowing while at it;
> > > > * the above turned up two spots that were wrongly accessing TREE_PURPOSE
> > > >   directly instead of using get_attribute_name;
> > > > * give error only for [[noreturn]] but not for __attribute__((noreturn))
> > > >   or [[gnu::noreturn]].
> > > > 
> > > > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> > > 
> > > I'd prefer to defer review of this to Jason, just want to note that I don't
> > > see any testsuite coverage on mixing declarations with different forms of
> > > attributes ([[noreturn]] on one decl and __attribute__((noreturn)) or
> > > [[gnu::noreturn]] on another one or vice versa.
> > 
> > Added now.  I suppose it should compile fine, which it does.
> 
> I meant also the tests of the new diagnostics, say if you have
> a decl without any of those attributes, then gnu:: one (or __attribute__
> one; that merge decls should be ok) and on third decl [[noreturn]] (shall
> that diagnose anything or not?  As there is no way to differentiate it from
> the gnu:: attribute on the very first one, I'd say it shouldn't, with the
> use of the gnu:: or __attribute__ we are already outside of the standard.

I've added noreturn-11.C for that.  With my patch we don't diagnose

void f1 ();
void f1 [[gnu::noreturn]] ();
void f1 [[noreturn]] ();

but that seems fine to me, too.  Of course there's the problem that we only
check the previous decl, not the first one, but I guess we'll have to live
with it; it will detect the bogus cases anyway.

--
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Jeff Law]

On 6/17/19 12:10 PM, Marek Polacek wrote:
> On Mon, Jun 17, 2019 at 09:02:17AM -0600, Martin Sebor wrote:
>>> diff --git gcc/cp/tree.c gcc/cp/tree.c
>>> index cd021b7f594..bb695e14e73 100644
>>> --- gcc/cp/tree.c
>>> +++ gcc/cp/tree.c
>>> @@ -4453,6 +4453,8 @@ const struct attribute_spec std_attribute_table[] =
>>>       handle_likeliness_attribute, attr_cold_hot_exclusions },
>>>     { "unlikely", 0, 0, false, false, false, false,
>>>       handle_likeliness_attribute, attr_cold_hot_exclusions },
>>> +  { "noreturn", 0, 0, true, false, false, false,
>>> +    handle_noreturn_attribute, NULL },
>>                                   ^^^^
>>
>> The GNU attribute is made mutually exclusive with a bunch of other
>> attributes (e.g., malloc or warn_unused_result) by setting the last
>> member to the array of exclusive attribute.  Does the change preserve
>> this relationship some other way?
> Oop, no, that is a bug.  I meant to go back to that, but I'd forgotten to add
> an XXX comment as I'm wont to, and the testsuite doesn't test that, so it
> slipped.  Fixed & new test added.  Thanks for catching it.
> 
> Also added a test for the scenario Jakub pointed out in the other mail.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> 2019-06-17  Marek Polacek  <polacek@redhat.com>
> 
> 	PR c++/60364 - noreturn after first decl not diagnosed.
> 	* attribs.c (get_attribute_namespace): No longer static.
> 	(decl_attributes): Avoid shadowing.  Preserve the C++11 form for C++11
> 	attributes.
> 	(attr_noreturn_exclusions): Make it extern.
> 	* attribs.h (get_attribute_namespace): Declare.
> 	* tree-inline.c (function_attribute_inlinable_p): Use
> 	get_attribute_name.
> 
> 	* c-attribs.c (handle_noreturn_attribute): No longer static.
> 	* c-common.h (handle_noreturn_attribute, attr_noreturn_exclusions):
> 	Declare.
> 	* c-format.c (check_function_format): Use get_attribute_name.
> 
> 	* decl.c (duplicate_decls): Give an error when a function is
> 	declared [[noreturn]] after its first declaration.
> 	* parser.c (cp_parser_std_attribute): Don't treat C++11 noreturn
> 	attribute as equivalent to GNU's.
> 	* tree.c (std_attribute_table): Add noreturn.
> 
> 	* g++.dg/warn/noreturn-8.C: New test.
> 	* g++.dg/warn/noreturn-9.C: New test.
> 	* g++.dg/warn/noreturn-10.C: New test.
> 	* g++.dg/warn/noreturn-11.C: New test.
> 
Turns out there was more generic stuff than C++ specific stuff here. So
I went ahead and walked through it.

OK for the trunk.

jeff

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Joseph Myers]

This (commit r272486) introduces an ICE building libstdc++-v3 for 
sh4-linux-gnu.

libtool: compile:  
/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/./gcc/xgcc 
-shared-libgcc 
-B/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/./gcc 
-nostdinc++ 
-L/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/src 
-L/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/src/.libs 
-L/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/libsupc++/.libs 
-B/scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/bin/ 
-B/scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/lib/ 
-isystem 
/scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/include 
-isystem 
/scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/sys-include 
-I/scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/../libgcc 
-I/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/include/sh4-glibc-linux-gnu 
-I/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/include 
-I/scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++ 
-D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra -Wwrite-strings 
-Wcast-qual -Wabi=2 -fdiagnostics-show-location=once -ffunction-sections 
-fdata-sections -frandom-seed=new_opa.lo -g -O2 -D_GNU_SOURCE -std=gnu++1z 
-c /scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++/new_opa.cc  
-fPIC -DPIC -D_GLIBCXX_SHARED -o new_opa.o
during RTL pass: final
/scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++/new_opa.cc: In function 'void* operator new(std::size_t, std::align_val_t)':
/scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++/new_opa.cc:132:1: internal compiler error: tree check: expected identifier_node, have tree_list in is_attribute_p, at attribs.h:155
  132 | }
      | ^
0x5b320d tree_check_failed(tree_node const*, char const*, int, char const*, ...)
        /scratch/jmyers/glibc-bot/src/gcc/gcc/tree.c:9899
0x5b3f0d tree_check(tree_node const*, char const*, int, char const*, 
tree_code)
        /scratch/jmyers/glibc-bot/src/gcc/gcc/tree.h:3453
0x5b3f0d is_attribute_p
        /scratch/jmyers/glibc-bot/src/gcc/gcc/attribs.h:155
0x11884c3 is_attribute_p
        /scratch/jmyers/glibc-bot/src/gcc/gcc/tree.h:3197
0x11884c3 sh2a_function_vector_p
        /scratch/jmyers/glibc-bot/src/gcc/gcc/config/sh/sh.c:8649
0x1188527 sh_encode_section_info
        /scratch/jmyers/glibc-bot/src/gcc/gcc/config/sh/sh.c:1570
0x1153ba8 make_decl_rtl(tree_node*)
        /scratch/jmyers/glibc-bot/src/gcc/gcc/varasm.c:1524
0x115460c get_fnname_from_decl(tree_node*)
        /scratch/jmyers/glibc-bot/src/gcc/gcc/varasm.c:1720
0xab2aa9 rest_of_handle_final
        /scratch/jmyers/glibc-bot/src/gcc/gcc/final.c:4648
0xab2aa9 execute
        /scratch/jmyers/glibc-bot/src/gcc/gcc/final.c:4737
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Makefile:960: recipe for target 'new_opa.lo' failed
make[5]: *** [new_opa.lo] Error 1

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Marek Polacek]

On Thu, Jun 20, 2019 at 04:43:58PM +0000, Joseph Myers wrote:
> This (commit r272486) introduces an ICE building libstdc++-v3 for 
> sh4-linux-gnu.
> 
> libtool: compile:  
> /scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/./gcc/xgcc 
> -shared-libgcc 
> -B/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/./gcc 
> -nostdinc++ 
> -L/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/src 
> -L/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/src/.libs 
> -L/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/libsupc++/.libs 
> -B/scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/bin/ 
> -B/scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/lib/ 
> -isystem 
> /scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/include 
> -isystem 
> /scratch/jmyers/glibc-bot/install/compilers/sh4-linux-gnu/sh4-glibc-linux-gnu/sys-include 
> -I/scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/../libgcc 
> -I/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/include/sh4-glibc-linux-gnu 
> -I/scratch/jmyers/glibc-bot/build/compilers/sh4-linux-gnu/gcc/sh4-glibc-linux-gnu/libstdc++-v3/include 
> -I/scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++ 
> -D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra -Wwrite-strings 
> -Wcast-qual -Wabi=2 -fdiagnostics-show-location=once -ffunction-sections 
> -fdata-sections -frandom-seed=new_opa.lo -g -O2 -D_GNU_SOURCE -std=gnu++1z 
> -c /scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++/new_opa.cc  
> -fPIC -DPIC -D_GLIBCXX_SHARED -o new_opa.o
> during RTL pass: final
> /scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++/new_opa.cc: In function 'void* operator new(std::size_t, std::align_val_t)':
> /scratch/jmyers/glibc-bot/src/gcc/libstdc++-v3/libsupc++/new_opa.cc:132:1: internal compiler error: tree check: expected identifier_node, have tree_list in is_attribute_p, at attribs.h:155
>   132 | }
>       | ^
> 0x5b320d tree_check_failed(tree_node const*, char const*, int, char const*, ...)
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/tree.c:9899
> 0x5b3f0d tree_check(tree_node const*, char const*, int, char const*, 
> tree_code)
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/tree.h:3453
> 0x5b3f0d is_attribute_p
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/attribs.h:155
> 0x11884c3 is_attribute_p
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/tree.h:3197
> 0x11884c3 sh2a_function_vector_p
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/config/sh/sh.c:8649
> 0x1188527 sh_encode_section_info
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/config/sh/sh.c:1570
> 0x1153ba8 make_decl_rtl(tree_node*)
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/varasm.c:1524
> 0x115460c get_fnname_from_decl(tree_node*)
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/varasm.c:1720
> 0xab2aa9 rest_of_handle_final
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/final.c:4648
> 0xab2aa9 execute
>         /scratch/jmyers/glibc-bot/src/gcc/gcc/final.c:4737
> Please submit a full bug report,
> with preprocessed source if appropriate.
> Please include the complete backtrace with any bug report.
> See <https://gcc.gnu.org/bugs/> for instructions.
> Makefile:960: recipe for target 'new_opa.lo' failed
> make[5]: *** [new_opa.lo] Error 1

Sorry about that.  Does this patch work?

2019-06-20  Marek Polacek  <polacek@redhat.com>

	* config/sh/sh.c (sh2a_function_vector_p): Use get_attribute_name.

diff --git gcc/config/sh/sh.c gcc/config/sh/sh.c
index 07d5b3c1df5..dfaeab55142 100644
--- gcc/config/sh/sh.c
+++ gcc/config/sh/sh.c
@@ -8646,7 +8646,7 @@ sh2a_function_vector_p (tree func)
     return false;
 
   for (tree list = SH_ATTRIBUTES (func); list; list = TREE_CHAIN (list))
-    if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
+    if (is_attribute_p ("function_vector", get_attribute_name (list)))
       return true;
 
   return false;

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Joseph Myers]

On Thu, 20 Jun 2019, Marek Polacek wrote:

> Sorry about that.  Does this patch work?

Yes, that fixes it, thanks.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Marek Polacek]

On Thu, Jun 20, 2019 at 05:08:37PM +0000, Joseph Myers wrote:
> On Thu, 20 Jun 2019, Marek Polacek wrote:
> 
> > Sorry about that.  Does this patch work?
> 
> Yes, that fixes it, thanks.

Great, I've applied the patch.

Marek

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Jakub Jelinek]

On Thu, Jun 20, 2019 at 12:49:13PM -0400, Marek Polacek wrote:
> Sorry about that.  Does this patch work?
> 
> 2019-06-20  Marek Polacek  <polacek@redhat.com>
> 
> 	* config/sh/sh.c (sh2a_function_vector_p): Use get_attribute_name.

Just that?
grep is_attribute_p.*TREE_PURPOSE config/*/*
config/m32c/m32c.c:      if (is_attribute_p ("interrupt", TREE_PURPOSE (list)))
config/m32c/m32c.c:      if (is_attribute_p ("bank_switch", TREE_PURPOSE (list)))
config/m32c/m32c.c:      if (is_attribute_p ("fast_interrupt", TREE_PURPOSE (list)))
config/m32c/m32c.c:      if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
config/m32c/m32c.c:          if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
config/rl78/rl78.c:      if (is_attribute_p ("saddr", TREE_PURPOSE (list)))
config/sh/sh.c:	      if (is_attribute_p ("sp_switch", TREE_PURPOSE (attrs))
config/sh/sh.c:		  || is_attribute_p ("trap_exit", TREE_PURPOSE (attrs))
config/sh/sh.c:		  || is_attribute_p ("nosave_low_regs", TREE_PURPOSE (attrs))
config/sh/sh.c:		  || is_attribute_p ("resbank", TREE_PURPOSE (attrs)))
config/sh/sh.c:	if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
config/sh/sh.c:    if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))

> diff --git gcc/config/sh/sh.c gcc/config/sh/sh.c
> index 07d5b3c1df5..dfaeab55142 100644
> --- gcc/config/sh/sh.c
> +++ gcc/config/sh/sh.c
> @@ -8646,7 +8646,7 @@ sh2a_function_vector_p (tree func)
>      return false;
>  
>    for (tree list = SH_ATTRIBUTES (func); list; list = TREE_CHAIN (list))
> -    if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
> +    if (is_attribute_p ("function_vector", get_attribute_name (list)))
>        return true;
>  
>    return false;

	Jakub

Re: C++ PATCH for c++/60364 - noreturn after first decl not diagnosed (v2)

[Marek Polacek]

On Thu, Jun 20, 2019 at 07:57:08PM +0200, Jakub Jelinek wrote:
> On Thu, Jun 20, 2019 at 12:49:13PM -0400, Marek Polacek wrote:
> > Sorry about that.  Does this patch work?
> > 
> > 2019-06-20  Marek Polacek  <polacek@redhat.com>
> > 
> > 	* config/sh/sh.c (sh2a_function_vector_p): Use get_attribute_name.
> 
> Just that?
> grep is_attribute_p.*TREE_PURPOSE config/*/*
> config/m32c/m32c.c:      if (is_attribute_p ("interrupt", TREE_PURPOSE (list)))
> config/m32c/m32c.c:      if (is_attribute_p ("bank_switch", TREE_PURPOSE (list)))
> config/m32c/m32c.c:      if (is_attribute_p ("fast_interrupt", TREE_PURPOSE (list)))
> config/m32c/m32c.c:      if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
> config/m32c/m32c.c:          if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
> config/rl78/rl78.c:      if (is_attribute_p ("saddr", TREE_PURPOSE (list)))
> config/sh/sh.c:	      if (is_attribute_p ("sp_switch", TREE_PURPOSE (attrs))
> config/sh/sh.c:		  || is_attribute_p ("trap_exit", TREE_PURPOSE (attrs))
> config/sh/sh.c:		  || is_attribute_p ("nosave_low_regs", TREE_PURPOSE (attrs))
> config/sh/sh.c:		  || is_attribute_p ("resbank", TREE_PURPOSE (attrs)))
> config/sh/sh.c:	if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
> config/sh/sh.c:    if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))

Here's a bunch of more; I've audited the uses of TREE_PURPOSE in config/*/*.

I haven't tested it or anything, but... ok for trunk?

2019-06-20  Marek Polacek  <polacek@redhat.com>

	* config/epiphany/epiphany.c (epiphany_compute_function_type): Use
	get_attribute_name.
	* config/m32c/m32c.c (interrupt_p): Likewise.
	(bank_switch_p): Likewise.
	(fast_interrupt_p): Likewise.
	(m32c_special_page_vector_p): Likewise.
	(current_function_special_page_vector): Likewise.
	* config/nds32/nds32.c (nds32_asm_function_prologue): Likewise.
	* config/rl78/rl78.c (rl78_attrlist_to_encoding): Likewise.
	* config/sh/sh.c (sh_insert_attributes): Likewise.
	(sh2a_get_function_vector_number): Likewise.

diff --git gcc/config/epiphany/epiphany.c gcc/config/epiphany/epiphany.c
index 657a8886ac7..2cc6c59eae3 100644
--- gcc/config/epiphany/epiphany.c
+++ gcc/config/epiphany/epiphany.c
@@ -1044,7 +1044,7 @@ epiphany_compute_function_type (tree decl)
        a;
        a = TREE_CHAIN (a))
     {
-      tree name = TREE_PURPOSE (a);
+      tree name = get_attribute_name (a);
 
       if (name == get_identifier ("interrupt"))
 	fn_type = EPIPHANY_FUNCTION_INTERRUPT;
diff --git gcc/config/m32c/m32c.c gcc/config/m32c/m32c.c
index 1a0d0c681b4..bda56e3beee 100644
--- gcc/config/m32c/m32c.c
+++ gcc/config/m32c/m32c.c
@@ -2858,7 +2858,7 @@ interrupt_p (tree node ATTRIBUTE_UNUSED)
   tree list = M32C_ATTRIBUTES (node);
   while (list)
     {
-      if (is_attribute_p ("interrupt", TREE_PURPOSE (list)))
+      if (is_attribute_p ("interrupt", get_attribute_name (list)))
 	return 1;
       list = TREE_CHAIN (list);
     }
@@ -2872,7 +2872,7 @@ bank_switch_p (tree node ATTRIBUTE_UNUSED)
   tree list = M32C_ATTRIBUTES (node);
   while (list)
     {
-      if (is_attribute_p ("bank_switch", TREE_PURPOSE (list)))
+      if (is_attribute_p ("bank_switch", get_attribute_name (list)))
 	return 1;
       list = TREE_CHAIN (list);
     }
@@ -2886,7 +2886,7 @@ fast_interrupt_p (tree node ATTRIBUTE_UNUSED)
   tree list = M32C_ATTRIBUTES (node);
   while (list)
     {
-      if (is_attribute_p ("fast_interrupt", TREE_PURPOSE (list)))
+      if (is_attribute_p ("fast_interrupt", get_attribute_name (list)))
 	return 1;
       list = TREE_CHAIN (list);
     }
@@ -2915,7 +2915,7 @@ m32c_special_page_vector_p (tree func)
   list = M32C_ATTRIBUTES (func);
   while (list)
     {
-      if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
+      if (is_attribute_p ("function_vector", get_attribute_name (list)))
         return 1;
       list = TREE_CHAIN (list);
     }
@@ -2984,7 +2984,7 @@ current_function_special_page_vector (rtx x)
       list = M32C_ATTRIBUTES (t);
       while (list)
         {
-          if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
+          if (is_attribute_p ("function_vector", get_attribute_name (list)))
             {
               num = TREE_INT_CST_LOW (TREE_VALUE (TREE_VALUE (list)));
               return num;
diff --git gcc/config/nds32/nds32.c gcc/config/nds32/nds32.c
index eba98126705..ea532ce1eb3 100644
--- gcc/config/nds32/nds32.c
+++ gcc/config/nds32/nds32.c
@@ -2190,7 +2190,7 @@ nds32_asm_function_prologue (FILE *file)
   /* Display all attributes of this function.  */
   while (attrs)
     {
-      name = TREE_PURPOSE (attrs);
+      name = get_attribute_name (attrs);
       fprintf (file, "%s ", IDENTIFIER_POINTER (name));
 
       /* Pick up the next attribute.  */
diff --git gcc/config/rl78/rl78.c gcc/config/rl78/rl78.c
index d2caa118281..067b966b48d 100644
--- gcc/config/rl78/rl78.c
+++ gcc/config/rl78/rl78.c
@@ -4532,7 +4532,7 @@ rl78_attrlist_to_encoding (tree list, tree decl ATTRIBUTE_UNUSED)
 {
   while (list)
     {
-      if (is_attribute_p ("saddr", TREE_PURPOSE (list)))
+      if (is_attribute_p ("saddr", get_attribute_name (list)))
 	return 's';
       list = TREE_CHAIN (list);
     }
diff --git gcc/config/sh/sh.c gcc/config/sh/sh.c
index dfaeab55142..5354d7960b0 100644
--- gcc/config/sh/sh.c
+++ gcc/config/sh/sh.c
@@ -8360,16 +8360,17 @@ sh_insert_attributes (tree node, tree *attributes)
 
 	  for (tail = attributes; attrs; attrs = TREE_CHAIN (attrs))
 	    {
-	      if (is_attribute_p ("sp_switch", TREE_PURPOSE (attrs))
-		  || is_attribute_p ("trap_exit", TREE_PURPOSE (attrs))
-		  || is_attribute_p ("nosave_low_regs", TREE_PURPOSE (attrs))
-		  || is_attribute_p ("resbank", TREE_PURPOSE (attrs)))
+	      if (is_attribute_p ("sp_switch", get_attribute_name (attrs))
+		  || is_attribute_p ("trap_exit", get_attribute_name (attrs))
+		  || is_attribute_p ("nosave_low_regs",
+				     get_attribute_name (attrs))
+		  || is_attribute_p ("resbank", get_attribute_name (attrs)))
 		warning (OPT_Wattributes,
 			 "%qE attribute only applies to interrupt functions",
-			 TREE_PURPOSE (attrs));
+			 get_attribute_name (attrs));
 	      else
 		{
-		  *tail = tree_cons (TREE_PURPOSE (attrs), NULL_TREE,
+		  *tail = tree_cons (get_attribute_name (attrs), NULL_TREE,
 				     NULL_TREE);
 		  tail = &TREE_CHAIN (*tail);
 		}
@@ -8537,7 +8538,7 @@ sh2a_get_function_vector_number (rtx x)
 	return 0;
 
       for (tree list = SH_ATTRIBUTES (t); list; list = TREE_CHAIN (list))
-	if (is_attribute_p ("function_vector", TREE_PURPOSE (list)))
+	if (is_attribute_p ("function_vector", get_attribute_name (list)))
 	  return TREE_INT_CST_LOW (TREE_VALUE (TREE_VALUE (list)));
 
       return 0;