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.

This is the third issue I found.

https://eel.is/c++draft/class.derived#general-1 has attribute-specifier-seq
at the start of base-specifier.  The following patch parses it there and
warns about those.

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

OK.

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

        PR c++/110345
        * parser.cc (cp_parser_base_specifier): Parse standard attributes
        at the start and emit a warning if there are any non-ignored ones.

        * g++.dg/cpp0x/gen-attrs-83.C: New test.

--- gcc/cp/parser.cc.jj 2024-08-15 17:41:44.554159692 +0200
+++ gcc/cp/parser.cc    2024-08-15 18:00:33.202211372 +0200
@@ -28987,11 +28987,12 @@ cp_parser_base_clause (cp_parser* parser
  /* Parse a base-specifier.
base-specifier:
-     :: [opt] nested-name-specifier [opt] class-name
-     virtual access-specifier [opt] :: [opt] nested-name-specifier
-       [opt] class-name
-     access-specifier virtual [opt] :: [opt] nested-name-specifier
-       [opt] class-name
+     attribute-specifier-seq [opt] :: [opt] nested-name-specifier [opt]
+       class-name
+     attribute-specifier-seq [opt] virtual access-specifier [opt] :: [opt]
+       nested-name-specifier [opt] class-name
+     attribute-specifier-seq [opt] access-specifier virtual [opt] :: [opt]
+       nested-name-specifier [opt] class-name
Returns a TREE_LIST. The TREE_PURPOSE will be one of
     ACCESS_{DEFAULT,PUBLIC,PROTECTED,PRIVATE}_[VIRTUAL]_NODE to
@@ -29009,6 +29010,12 @@ cp_parser_base_specifier (cp_parser* par
    bool class_scope_p, template_p;
    tree access = access_default_node;
    tree type;
+  location_t attrs_loc = cp_lexer_peek_token (parser->lexer)->location;
+  tree std_attrs = cp_parser_std_attribute_spec_seq (parser);
+
+  if (std_attrs != NULL_TREE && any_nonignored_attribute_p (std_attrs))
+    warning_at (attrs_loc, OPT_Wattributes,
+                "attributes on base specifiers are ignored");
/* Process the optional `virtual' and `access-specifier'. */
    while (!done)
--- gcc/testsuite/g++.dg/cpp0x/gen-attrs-83.C.jj        2024-08-15 
17:58:52.093456428 +0200
+++ gcc/testsuite/g++.dg/cpp0x/gen-attrs-83.C   2024-08-15 18:27:23.864431390 
+0200
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++11 } }
+
+struct A {};
+struct B {};
+struct C {};
+struct D : [[]] [[]] A,
+          [[]] virtual public B, [[]] [[]] [[]] public virtual C {};
+struct E : [[gnu::deprecated]] A,                      // { dg-warning "attributes 
on base specifiers are ignored" }
+          [[gnu::deprecated]] virtual public B,        // { dg-warning "attributes 
on base specifiers are ignored" }
+          [[gnu::deprecated]] public virtual C {};     // { dg-warning "attributes 
on base specifiers are ignored" }

        Jakub


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