c++, v2: Don't diagnose ignoring of attributes if all ignored attributes are attribute_ignored_p

Message ID ZXNX/AUfHDOf+57y@tucnak
State New
Headers
Series c++, v2: Don't diagnose ignoring of attributes if all ignored attributes are attribute_ignored_p |

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Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-arm fail Patch failed to apply
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Commit Message

Jakub Jelinek Dec. 8, 2023, 5:53 p.m. UTC
  On Fri, Dec 08, 2023 at 12:06:01PM -0500, Jason Merrill wrote:
> > @@ -21111,7 +21116,7 @@ cp_parser_elaborated_type_specifier (cp_
> >   	}
> >         else if (is_declaration && cp_parser_declares_only_class_p (parser))
> >   	cplus_decl_attributes (&type, attributes, (int) ATTR_FLAG_TYPE_IN_PLACE);
> > -      else
> > +      else if (any_nonignored_attribute_p (attributes))
> >   	warning (OPT_Wattributes,
> >   		 "attributes ignored on elaborated-type-specifier that is "
> >   		 "not a forward declaration");
> 
> I believe this is also prohibited by
> https://eel.is/c++draft/dcl.type.elab#3

You're right and there is also
https://eel.is/c++draft/temp.spec#temp.explicit-3
which prohibits it for explicit template instantiations.

> so I would leave all the warnings in this function alone.

Ok.

> >         location_t attr_loc = declspecs->locations[ds_std_attribute];
> > -      if (warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
> > +      if (any_nonignored_attribute_p (declspecs->std_attributes)
> > +	  && warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
> >   	inform (attr_loc, "an attribute that appertains to a type-specifier "
> >   		"is ignored");
> >       }
> 
> This seems untested, e.g.
> 
> int [[foo::bar]] i;

Thanks.

Here is an updated patch, so far tested with
GXX_TESTSUITE_STDS=98,11,14,17,20,23,26 make check-g++ RUNTESTFLAGS="dg.exp='Wno-attributes*' ubsan.exp=Wno-attributes*"
Ok for trunk if it passes full bootstrap/regtest?

2023-12-08  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* attribs.h (any_nonignored_attribute_p): Declare.
	* attribs.cc (any_nonignored_attribute_p): New function.
gcc/cp/
	* parser.cc (cp_parser_statement, cp_parser_expression_statement,
	cp_parser_declaration, cp_parser_asm_definition): Don't diagnose
	ignored attributes if !any_nonignored_attribute_p.
	* decl.cc (grokdeclarator): Likewise.
	* name-lookup.cc (handle_namespace_attrs, finish_using_directive):
	Don't diagnose ignoring of attr_ignored_p attributes.
gcc/testsuite/
	* g++.dg/warn/Wno-attributes-1.C: New test.



	Jakub
  

Comments

Jason Merrill Dec. 8, 2023, 7:48 p.m. UTC | #1
On 12/8/23 12:53, Jakub Jelinek wrote:
> On Fri, Dec 08, 2023 at 12:06:01PM -0500, Jason Merrill wrote:
>>> @@ -21111,7 +21116,7 @@ cp_parser_elaborated_type_specifier (cp_
>>>    	}
>>>          else if (is_declaration && cp_parser_declares_only_class_p (parser))
>>>    	cplus_decl_attributes (&type, attributes, (int) ATTR_FLAG_TYPE_IN_PLACE);
>>> -      else
>>> +      else if (any_nonignored_attribute_p (attributes))
>>>    	warning (OPT_Wattributes,
>>>    		 "attributes ignored on elaborated-type-specifier that is "
>>>    		 "not a forward declaration");
>>
>> I believe this is also prohibited by
>> https://eel.is/c++draft/dcl.type.elab#3
> 
> You're right and there is also
> https://eel.is/c++draft/temp.spec#temp.explicit-3
> which prohibits it for explicit template instantiations.
> 
>> so I would leave all the warnings in this function alone.
> 
> Ok.
> 
>>>          location_t attr_loc = declspecs->locations[ds_std_attribute];
>>> -      if (warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
>>> +      if (any_nonignored_attribute_p (declspecs->std_attributes)
>>> +	  && warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
>>>    	inform (attr_loc, "an attribute that appertains to a type-specifier "
>>>    		"is ignored");
>>>        }
>>
>> This seems untested, e.g.
>>
>> int [[foo::bar]] i;
> 
> Thanks.
> 
> Here is an updated patch, so far tested with
> GXX_TESTSUITE_STDS=98,11,14,17,20,23,26 make check-g++ RUNTESTFLAGS="dg.exp='Wno-attributes*' ubsan.exp=Wno-attributes*"
> Ok for trunk if it passes full bootstrap/regtest?

OK.

> 2023-12-08  Jakub Jelinek  <jakub@redhat.com>
> 
> gcc/
> 	* attribs.h (any_nonignored_attribute_p): Declare.
> 	* attribs.cc (any_nonignored_attribute_p): New function.
> gcc/cp/
> 	* parser.cc (cp_parser_statement, cp_parser_expression_statement,
> 	cp_parser_declaration, cp_parser_asm_definition): Don't diagnose
> 	ignored attributes if !any_nonignored_attribute_p.
> 	* decl.cc (grokdeclarator): Likewise.
> 	* name-lookup.cc (handle_namespace_attrs, finish_using_directive):
> 	Don't diagnose ignoring of attr_ignored_p attributes.
> gcc/testsuite/
> 	* g++.dg/warn/Wno-attributes-1.C: New test.
> 
> --- gcc/attribs.h.jj	2023-12-06 12:03:27.421176109 +0100
> +++ gcc/attribs.h	2023-12-06 12:36:55.704884514 +0100
> @@ -48,6 +48,7 @@ extern void apply_tm_attr (tree, tree);
>   extern tree make_attribute (const char *, const char *, tree);
>   extern bool attribute_ignored_p (tree);
>   extern bool attribute_ignored_p (const attribute_spec *const);
> +extern bool any_nonignored_attribute_p (tree);
>   
>   extern struct scoped_attributes *
>     register_scoped_attributes (const scoped_attribute_specs &, bool = false);
> --- gcc/attribs.cc.jj	2023-12-06 12:03:27.386176602 +0100
> +++ gcc/attribs.cc	2023-12-06 12:36:55.704884514 +0100
> @@ -584,6 +584,19 @@ attribute_ignored_p (const attribute_spe
>     return as->max_length == -2;
>   }
>   
> +/* Return true if the ATTRS chain contains at least one attribute which
> +   is not ignored.  */
> +
> +bool
> +any_nonignored_attribute_p (tree attrs)
> +{
> +  for (tree attr = attrs; attr; attr = TREE_CHAIN (attr))
> +    if (!attribute_ignored_p (attr))
> +      return true;
> +
> +  return false;
> +}
> +
>   /* See whether LIST contains at least one instance of attribute ATTR
>      (possibly with different arguments).  Return the first such attribute
>      if so, otherwise return null.  */
> --- gcc/cp/parser.cc.jj	2023-12-06 12:03:27.502174967 +0100
> +++ gcc/cp/parser.cc	2023-12-06 12:36:55.704884514 +0100
> @@ -12778,9 +12778,8 @@ cp_parser_statement (cp_parser* parser,
>       SET_EXPR_LOCATION (statement, statement_location);
>   
>     /* Allow "[[fallthrough]];" or "[[assume(cond)]];", but warn otherwise.  */
> -  if (std_attrs != NULL_TREE)
> -    warning_at (attrs_loc,
> -		OPT_Wattributes,
> +  if (std_attrs != NULL_TREE && any_nonignored_attribute_p (std_attrs))
> +    warning_at (attrs_loc, OPT_Wattributes,
>   		"attributes at the beginning of statement are ignored");
>   }
>   
> @@ -12986,7 +12985,7 @@ cp_parser_expression_statement (cp_parse
>       }
>   
>     /* Allow "[[fallthrough]];", but warn otherwise.  */
> -  if (attr != NULL_TREE)
> +  if (attr != NULL_TREE && any_nonignored_attribute_p (attr))
>       warning_at (loc, OPT_Wattributes,
>   		"attributes at the beginning of statement are ignored");
>   
> @@ -15191,7 +15190,7 @@ cp_parser_declaration (cp_parser* parser
>   	    }
>   	}
>   
> -      if (std_attrs != NULL_TREE && !attribute_ignored_p (std_attrs))
> +      if (std_attrs != NULL_TREE && any_nonignored_attribute_p (std_attrs))
>   	warning_at (make_location (attrs_loc, attrs_loc, parser->lexer),
>   		    OPT_Wattributes, "attribute ignored");
>         if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
> @@ -22672,7 +22671,7 @@ cp_parser_asm_definition (cp_parser* par
>   	symtab->finalize_toplevel_asm (string);
>       }
>   
> -  if (std_attrs)
> +  if (std_attrs && any_nonignored_attribute_p (std_attrs))
>       warning_at (asm_loc, OPT_Wattributes,
>   		"attributes ignored on %<asm%> declaration");
>   }
> --- gcc/cp/decl.cc.jj	2023-12-06 12:03:27.483175235 +0100
> +++ gcc/cp/decl.cc	2023-12-06 12:36:55.698884598 +0100
> @@ -13058,7 +13058,8 @@ grokdeclarator (const cp_declarator *dec
>         && !diagnose_misapplied_contracts (declspecs->std_attributes))
>       {
>         location_t attr_loc = declspecs->locations[ds_std_attribute];
> -      if (warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
> +      if (any_nonignored_attribute_p (declspecs->std_attributes)
> +	  && warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
>   	inform (attr_loc, "an attribute that appertains to a type-specifier "
>   		"is ignored");
>       }
> --- gcc/cp/name-lookup.cc.jj	2023-12-06 12:03:27.495175066 +0100
> +++ gcc/cp/name-lookup.cc	2023-12-06 12:36:55.695884641 +0100
> @@ -6356,7 +6356,7 @@ handle_namespace_attrs (tree ns, tree at
>   	    DECL_ATTRIBUTES (ns) = tree_cons (name, args,
>   					      DECL_ATTRIBUTES (ns));
>   	}
> -      else
> +      else if (!attribute_ignored_p (d))
>   	{
>   	  warning (OPT_Wattributes, "%qD attribute directive ignored",
>   		   name);
> @@ -8703,7 +8703,7 @@ finish_using_directive (tree target, tre
>   		diagnosed = true;
>   	      }
>   	  }
> -	else
> +	else if (!attribute_ignored_p (a))
>   	  warning (OPT_Wattributes, "%qD attribute directive ignored", name);
>         }
>   }
> --- gcc/testsuite/g++.dg/warn/Wno-attributes-1.C.jj	2023-12-06 14:27:29.006249075 +0100
> +++ gcc/testsuite/g++.dg/warn/Wno-attributes-1.C	2023-12-08 18:50:36.077628959 +0100
> @@ -0,0 +1,52 @@
> +// { dg-do compile { target c++11 } }
> +// { dg-options "-Wno-attributes=bar:: -Wno-attributes=baz::qux" }
> +
> +[[foo::bar]];				// { dg-warning "attribute ignored" }
> +[[bar::foo, foo::bar, baz::qux]];	// { dg-warning "attribute ignored" }
> +[[bar::foo, bar::bar, baz::qux]];	// { dg-bogus "attribute ignored" }
> +
> +namespace [[foo::bar]] N {		// { dg-warning "'bar' attribute directive ignored" }
> +  int n;
> +}
> +namespace [[bar::foo, foo::bar, baz::qux]] O { // { dg-warning "'bar' attribute directive ignored" }
> +  int o;
> +}
> +namespace [[bar::foo, bar::bar, baz::qux]] P { // { dg-bogus "attribute directive ignored" }
> +  int p;
> +}
> +
> +void
> +foo ()
> +{
> +  int i = 0;
> +  [[foo::bar]];				// { dg-warning "attributes at the beginning of statement are ignored" }
> +  [[bar::foo, foo::bar, baz::qux]];	// { dg-warning "attributes at the beginning of statement are ignored" }
> +  [[bar::foo, bar::bar, baz::qux]];	// { dg-bogus "attributes at the beginning of statement are ignored" }
> +  [[foo::bar]] ++i;			// { dg-warning "attributes at the beginning of statement are ignored" }
> +  [[bar::foo, foo::bar, baz::qux]] ++i;	// { dg-warning "attributes at the beginning of statement are ignored" }
> +  [[bar::foo, bar::bar, baz::qux]] ++i;	// { dg-bogus "attributes at the beginning of statement are ignored" }
> +  [[foo::bar]] asm ("");		// { dg-warning "attributes ignored on 'asm' declaration" }
> +  [[bar::foo, foo::bar, baz::qux]] asm (""); // { dg-warning "attributes ignored on 'asm' declaration" }
> +  [[bar::foo, bar::bar, baz::qux]] asm (""); // { dg-bogus "attributes ignored on 'asm' declaration" }
> +  [[foo::bar]] using namespace N;	// { dg-warning "'bar' attribute directive ignored" }
> +  [[bar::foo, foo::bar, baz::qux]] using namespace O; // { dg-warning "'bar' attribute directive ignored" }
> +  [[bar::foo, bar::bar, baz::qux]] using namespace P; // { dg-bogus "attribute directive ignored" }
> +}
> +
> +class S
> +{
> +  [[foo::bar]] friend int bar (S &);	// { dg-warning "attribute ignored" }
> +					// { dsg-message "an attribute that appertains to a friend declaration that is not a definition is ignored" "" { target *-*-* } .-1 }
> +  [[bar::foo, foo::bar, baz::qux]] friend int baz (S &); // { dg-warning "attribute ignored" }
> +					// { dsg-message "an attribute that appertains to a friend declaration that is not a definition is ignored" "" { target *-*-* } .-1 }
> +  [[bar::foo, bar::bar, baz::qux]] friend int qux (S &); // { dg-warning "attribute ignored" }
> +					// { dsg-message "an attribute that appertains to a friend declaration that is not a definition is ignored" "" { target *-*-* } .-1 }
> +public:
> +  int s;
> +};
> +
> +int [[foo::bar]] i;			// { dg-warning "attribute ignored" }
> +					// { dg-message "an attribute that appertains to a type-specifier is ignored" "" { target *-*-* } .-1 }
> +int [[bar::foo, foo::bar, baz::qux]] j;	// { dg-warning "attribute ignored" }
> +					// { dg-message "an attribute that appertains to a type-specifier is ignored" "" { target *-*-* } .-1 }
> +int [[bar::foo, bar::bar, baz::qux]] k;	// { dg-bogus "attribute ignored" }
> 
> 
> 	Jakub
>
  

Patch

--- gcc/attribs.h.jj	2023-12-06 12:03:27.421176109 +0100
+++ gcc/attribs.h	2023-12-06 12:36:55.704884514 +0100
@@ -48,6 +48,7 @@  extern void apply_tm_attr (tree, tree);
 extern tree make_attribute (const char *, const char *, tree);
 extern bool attribute_ignored_p (tree);
 extern bool attribute_ignored_p (const attribute_spec *const);
+extern bool any_nonignored_attribute_p (tree);
 
 extern struct scoped_attributes *
   register_scoped_attributes (const scoped_attribute_specs &, bool = false);
--- gcc/attribs.cc.jj	2023-12-06 12:03:27.386176602 +0100
+++ gcc/attribs.cc	2023-12-06 12:36:55.704884514 +0100
@@ -584,6 +584,19 @@  attribute_ignored_p (const attribute_spe
   return as->max_length == -2;
 }
 
+/* Return true if the ATTRS chain contains at least one attribute which
+   is not ignored.  */
+
+bool
+any_nonignored_attribute_p (tree attrs)
+{
+  for (tree attr = attrs; attr; attr = TREE_CHAIN (attr))
+    if (!attribute_ignored_p (attr))
+      return true;
+
+  return false;
+}
+
 /* See whether LIST contains at least one instance of attribute ATTR
    (possibly with different arguments).  Return the first such attribute
    if so, otherwise return null.  */
--- gcc/cp/parser.cc.jj	2023-12-06 12:03:27.502174967 +0100
+++ gcc/cp/parser.cc	2023-12-06 12:36:55.704884514 +0100
@@ -12778,9 +12778,8 @@  cp_parser_statement (cp_parser* parser,
     SET_EXPR_LOCATION (statement, statement_location);
 
   /* Allow "[[fallthrough]];" or "[[assume(cond)]];", but warn otherwise.  */
-  if (std_attrs != NULL_TREE)
-    warning_at (attrs_loc,
-		OPT_Wattributes,
+  if (std_attrs != NULL_TREE && any_nonignored_attribute_p (std_attrs))
+    warning_at (attrs_loc, OPT_Wattributes,
 		"attributes at the beginning of statement are ignored");
 }
 
@@ -12986,7 +12985,7 @@  cp_parser_expression_statement (cp_parse
     }
 
   /* Allow "[[fallthrough]];", but warn otherwise.  */
-  if (attr != NULL_TREE)
+  if (attr != NULL_TREE && any_nonignored_attribute_p (attr))
     warning_at (loc, OPT_Wattributes,
 		"attributes at the beginning of statement are ignored");
 
@@ -15191,7 +15190,7 @@  cp_parser_declaration (cp_parser* parser
 	    }
 	}
 
-      if (std_attrs != NULL_TREE && !attribute_ignored_p (std_attrs))
+      if (std_attrs != NULL_TREE && any_nonignored_attribute_p (std_attrs))
 	warning_at (make_location (attrs_loc, attrs_loc, parser->lexer),
 		    OPT_Wattributes, "attribute ignored");
       if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
@@ -22672,7 +22671,7 @@  cp_parser_asm_definition (cp_parser* par
 	symtab->finalize_toplevel_asm (string);
     }
 
-  if (std_attrs)
+  if (std_attrs && any_nonignored_attribute_p (std_attrs))
     warning_at (asm_loc, OPT_Wattributes,
 		"attributes ignored on %<asm%> declaration");
 }
--- gcc/cp/decl.cc.jj	2023-12-06 12:03:27.483175235 +0100
+++ gcc/cp/decl.cc	2023-12-06 12:36:55.698884598 +0100
@@ -13058,7 +13058,8 @@  grokdeclarator (const cp_declarator *dec
       && !diagnose_misapplied_contracts (declspecs->std_attributes))
     {
       location_t attr_loc = declspecs->locations[ds_std_attribute];
-      if (warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
+      if (any_nonignored_attribute_p (declspecs->std_attributes)
+	  && warning_at (attr_loc, OPT_Wattributes, "attribute ignored"))
 	inform (attr_loc, "an attribute that appertains to a type-specifier "
 		"is ignored");
     }
--- gcc/cp/name-lookup.cc.jj	2023-12-06 12:03:27.495175066 +0100
+++ gcc/cp/name-lookup.cc	2023-12-06 12:36:55.695884641 +0100
@@ -6356,7 +6356,7 @@  handle_namespace_attrs (tree ns, tree at
 	    DECL_ATTRIBUTES (ns) = tree_cons (name, args,
 					      DECL_ATTRIBUTES (ns));
 	}
-      else
+      else if (!attribute_ignored_p (d))
 	{
 	  warning (OPT_Wattributes, "%qD attribute directive ignored",
 		   name);
@@ -8703,7 +8703,7 @@  finish_using_directive (tree target, tre
 		diagnosed = true;
 	      }
 	  }
-	else
+	else if (!attribute_ignored_p (a))
 	  warning (OPT_Wattributes, "%qD attribute directive ignored", name);
       }
 }
--- gcc/testsuite/g++.dg/warn/Wno-attributes-1.C.jj	2023-12-06 14:27:29.006249075 +0100
+++ gcc/testsuite/g++.dg/warn/Wno-attributes-1.C	2023-12-08 18:50:36.077628959 +0100
@@ -0,0 +1,52 @@ 
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wno-attributes=bar:: -Wno-attributes=baz::qux" }
+
+[[foo::bar]];				// { dg-warning "attribute ignored" }
+[[bar::foo, foo::bar, baz::qux]];	// { dg-warning "attribute ignored" }
+[[bar::foo, bar::bar, baz::qux]];	// { dg-bogus "attribute ignored" }
+
+namespace [[foo::bar]] N {		// { dg-warning "'bar' attribute directive ignored" }
+  int n;
+}
+namespace [[bar::foo, foo::bar, baz::qux]] O { // { dg-warning "'bar' attribute directive ignored" }
+  int o;
+}
+namespace [[bar::foo, bar::bar, baz::qux]] P { // { dg-bogus "attribute directive ignored" }
+  int p;
+}
+
+void
+foo ()
+{
+  int i = 0;
+  [[foo::bar]];				// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[bar::foo, foo::bar, baz::qux]];	// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[bar::foo, bar::bar, baz::qux]];	// { dg-bogus "attributes at the beginning of statement are ignored" }
+  [[foo::bar]] ++i;			// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[bar::foo, foo::bar, baz::qux]] ++i;	// { dg-warning "attributes at the beginning of statement are ignored" }
+  [[bar::foo, bar::bar, baz::qux]] ++i;	// { dg-bogus "attributes at the beginning of statement are ignored" }
+  [[foo::bar]] asm ("");		// { dg-warning "attributes ignored on 'asm' declaration" }
+  [[bar::foo, foo::bar, baz::qux]] asm (""); // { dg-warning "attributes ignored on 'asm' declaration" }
+  [[bar::foo, bar::bar, baz::qux]] asm (""); // { dg-bogus "attributes ignored on 'asm' declaration" }
+  [[foo::bar]] using namespace N;	// { dg-warning "'bar' attribute directive ignored" }
+  [[bar::foo, foo::bar, baz::qux]] using namespace O; // { dg-warning "'bar' attribute directive ignored" }
+  [[bar::foo, bar::bar, baz::qux]] using namespace P; // { dg-bogus "attribute directive ignored" }
+}
+
+class S
+{
+  [[foo::bar]] friend int bar (S &);	// { dg-warning "attribute ignored" }
+					// { dsg-message "an attribute that appertains to a friend declaration that is not a definition is ignored" "" { target *-*-* } .-1 }
+  [[bar::foo, foo::bar, baz::qux]] friend int baz (S &); // { dg-warning "attribute ignored" }
+					// { dsg-message "an attribute that appertains to a friend declaration that is not a definition is ignored" "" { target *-*-* } .-1 }
+  [[bar::foo, bar::bar, baz::qux]] friend int qux (S &); // { dg-warning "attribute ignored" }
+					// { dsg-message "an attribute that appertains to a friend declaration that is not a definition is ignored" "" { target *-*-* } .-1 }
+public:
+  int s;
+};
+
+int [[foo::bar]] i;			// { dg-warning "attribute ignored" }
+					// { dg-message "an attribute that appertains to a type-specifier is ignored" "" { target *-*-* } .-1 }
+int [[bar::foo, foo::bar, baz::qux]] j;	// { dg-warning "attribute ignored" }
+					// { dg-message "an attribute that appertains to a type-specifier is ignored" "" { target *-*-* } .-1 }
+int [[bar::foo, bar::bar, baz::qux]] k;	// { dg-bogus "attribute ignored" }