Re: [PATCH] c++: Allow standard attributes after closing square bracket in new-type-id [PR110345]

Jason Merrill Mon, 19 Aug 2024 14:18:37 -0700

On 8/15/24 4:53 PM, Jakub Jelinek wrote:

Hi!


For C++ 26 P2552R3 I went through all the spots (except modules) where
attribute-specifier-seq appears in the grammar and tried to construct
a testcase in all those spots, for now for [[deprecated]] attribute.

The first thing I found is that we aren't parsing standard attributes in
noptr-new-declarator - https://eel.is/c++draft/expr.new#1

The following patch parses it there, for the non-outermost arrays
applies normally the attributes to the array type, for the outermost
where we just set *nelts and don't really build an array type just
warns that we ignore those attributes (or, do you think we should
just build an array type in that case and just take its element type?).

It seems cleaner to just build an array type, and build_new_1 appears toalready handle that. But I don't think there are currently anyattributes that would be useful in this position, so this patch is finewith a FIXME if you don't want to mess with it.

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

2024-08-15  Jakub Jelinek  <ja...@redhat.com>

        PR c++/110345
        * parser.cc (make_array_declarator): Add STD_ATTRS argument, set
        declarator->std_attributes to it.
        (cp_parser_new_type_id): Warn on non-ignored std_attributes on the
        array declarator which is being omitted.
        (cp_parser_direct_new_declarator): Parse standard attributes after
        closing square bracket, pass it to make_array_declarator.
        (cp_parser_direct_declarator): Pass std_attrs to make_array_declarator
        instead of setting declarator->std_attributes manually.

        * g++.dg/cpp0x/gen-attrs-80.C: New test.
        * g++.dg/cpp0x/gen-attrs-81.C: New test.

--- gcc/cp/parser.cc.jj 2024-08-15 14:56:29.007757215 +0200
+++ gcc/cp/parser.cc    2024-08-15 16:28:18.607692746 +0200
@@ -1689,7 +1689,7 @@ static cp_declarator *make_call_declarat
    (cp_declarator *, tree, cp_cv_quals, cp_virt_specifiers, cp_ref_qualifier,
     tree, tree, tree, tree, tree, location_t);
  static cp_declarator *make_array_declarator
-  (cp_declarator *, tree);
+  (cp_declarator *, tree, tree);
  static cp_declarator *make_pointer_declarator
    (cp_cv_quals, cp_declarator *, tree);
  static cp_declarator *make_reference_declarator
@@ -1904,10 +1904,11 @@ make_call_declarator (cp_declarator *tar
  }

/* Make a declarator for an array of BOUNDS elements, each of which is

-   defined by ELEMENT.  */
+   defined by ELEMENT.  STD_ATTRS contains attributes that appertain to
+   the array type.  */

cp_declarator *

-make_array_declarator (cp_declarator *element, tree bounds)
+make_array_declarator (cp_declarator *element, tree bounds, tree std_attrs)
  {
    cp_declarator *declarator;

@@ -1923,6 +1924,8 @@ make_array_declarator (cp_declarator *el

    else
      declarator->parameter_pack_p = false;

+ declarator->std_attributes = std_attrs;

+
    return declarator;
  }

@@ -9784,6 +9787,12 @@ cp_parser_new_type_id (cp_parser* parser

        if (*nelts == error_mark_node)
        *nelts = integer_one_node;

+ if (*nelts

+         && declarator->std_attributes
+         && any_nonignored_attribute_p (declarator->std_attributes))
+       warning (OPT_Wattributes, "attributes ignored on outermost array "
+                                 "type in new expression");
+
        if (*nelts == NULL_TREE)
        /* Leave [] in the declarator.  */;
        else if (outer_declarator)
@@ -9838,8 +9847,8 @@ cp_parser_new_declarator_opt (cp_parser*
  /* Parse a direct-new-declarator.

direct-new-declarator:

-     [ expression ]
-     direct-new-declarator [constant-expression]
+     [ expression ] attribute-specifier-seq [opt]
+     direct-new-declarator [constant-expression] attribute-specifier-seq [opt]

*/@@ -9886,8 +9895,9 @@ cp_parser_direct_new_declarator (cp_pars

        /* Look for the closing `]'.  */
        cp_parser_require (parser, CPP_CLOSE_SQUARE, RT_CLOSE_SQUARE);

+ tree attrs = cp_parser_std_attribute_spec_seq (parser);

        /* Add this bound to the declarator.  */
-      declarator = make_array_declarator (declarator, expression);
+      declarator = make_array_declarator (declarator, expression, attrs);

/* If the next token is not a `[', then there are no more

         bounds.  */
@@ -24330,8 +24340,7 @@ cp_parser_direct_declarator (cp_parser*
            }

attrs = cp_parser_std_attribute_spec_seq (parser);

-         declarator = make_array_declarator (declarator, bounds);
-         declarator->std_attributes = attrs;
+         declarator = make_array_declarator (declarator, bounds, attrs);
        }
        else if (first && dcl_kind != CP_PARSER_DECLARATOR_ABSTRACT)
        {
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-80.C.jj        2024-08-15 
15:27:00.297061501 +0200
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-80.C   2024-08-15 15:27:19.610822213 
+0200
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++11 } }
+
+void
+foo (int n)
+{
+  auto a = new int [n] [[]];
+  auto b = new int [n] [[]] [42] [[]] [1] [[]];
+  delete[] b;
+  delete[] a;
+}
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-81.C.jj        2024-08-15 
17:14:43.912228130 +0200
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-81.C   2024-08-15 17:19:01.738038053 
+0200
@@ -0,0 +1,11 @@
+// { dg-do compile { target c++11 } }
+
+void
+foo (int n)
+{
+  auto a = new int [n] [[gnu::deprecated]];                            // { dg-warning 
"attributes ignored on outermost array type in new expression" }
+  auto b = new int [n] [[gnu::deprecated]] [42] [[]] [1] [[]];         // { dg-warning 
"attributes ignored on outermost array type in new expression" }
+  auto c = new int [n] [[]] [42] [[gnu::deprecated]] [1] [[gnu::deprecated]];
+  delete[] b;
+  delete[] a;
+}

        Jakub

Re: [PATCH] c++: Allow standard attributes after closing square bracket in new-type-id [PR110345]

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