diff mbox series

c++: Fix parsing of abstract-declarator starting with ... followed by [ or ( [PR115012]

Message ID Zj0SDsAyH4Tw7SGA@tucnak
State New
Headers show
Series c++: Fix parsing of abstract-declarator starting with ... followed by [ or ( [PR115012] | expand

Commit Message

Jakub Jelinek May 9, 2024, 6:12 p.m. UTC 
Hi!

The C++26 P2662R3 Pack indexing paper mentions that both GCC
and MSVC don't handle T...[10] parameter declaration when T
is a pack.  While that will change meaning in C++26, in C++11 .. C++23
this ought to be valid.  Also, T...(args) as well.

The following patch handles those in cp_parser_direct_declarator.

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

2024-05-09  Jakub Jelinek  <jakub@redhat.com>

	PR c++/115012
	* parser.cc (cp_parser_direct_declarator): Handle
	abstract declarator starting with ... followed by [
	or (.

	* g++.dg/cpp0x/variadic185.C: New test.
	* g++.dg/cpp0x/variadic186.C: New test.


	Jakub

Comments

Jakub Jelinek May 16, 2024, 1:13 p.m. UTC | #1 
Hi!

I'd like to ping the https://gcc.gnu.org/pipermail/gcc-patches/2024-May/651199.html
patch.

Thanks.

On Thu, May 09, 2024 at 08:12:30PM +0200, Jakub Jelinek wrote:
> The C++26 P2662R3 Pack indexing paper mentions that both GCC
> and MSVC don't handle T...[10] parameter declaration when T
> is a pack.  While that will change meaning in C++26, in C++11 .. C++23
> this ought to be valid.  Also, T...(args) as well.
> 
> The following patch handles those in cp_parser_direct_declarator.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> 2024-05-09  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c++/115012
> 	* parser.cc (cp_parser_direct_declarator): Handle
> 	abstract declarator starting with ... followed by [
> 	or (.
> 
> 	* g++.dg/cpp0x/variadic185.C: New test.
> 	* g++.dg/cpp0x/variadic186.C: New test.

	Jakub
diff mbox series

Patch

--- gcc/cp/parser.cc.jj	2024-05-09 10:30:58.000000000 +0200
+++ gcc/cp/parser.cc	2024-05-09 16:44:01.250777325 +0200
@@ -23916,7 +23916,12 @@  cp_parser_direct_declarator (cp_parser*
     {
       /* Peek at the next token.  */
       token = cp_lexer_peek_token (parser->lexer);
-      if (token->type == CPP_OPEN_PAREN)
+      if (token->type == CPP_OPEN_PAREN
+	  || (first
+	      && dcl_kind != CP_PARSER_DECLARATOR_NAMED
+	      && token->type == CPP_ELLIPSIS
+	      && cxx_dialect > cxx98
+	      && cp_lexer_nth_token_is (parser->lexer, 2, CPP_OPEN_PAREN)))
 	{
 	  /* This is either a parameter-declaration-clause, or a
 	     parenthesized declarator. When we know we are parsing a
@@ -23955,6 +23960,11 @@  cp_parser_direct_declarator (cp_parser*
 
 	     Thus again, we try a parameter-declaration-clause, and if
 	     that fails, we back out and return.  */
+	  bool pack_expansion_p = token->type == CPP_ELLIPSIS;
+
+	  if (pack_expansion_p)
+	    /* Consume the `...' */
+	    cp_lexer_consume_token (parser->lexer);
 
 	  if (!first || dcl_kind != CP_PARSER_DECLARATOR_NAMED)
 	    {
@@ -24098,6 +24108,7 @@  cp_parser_direct_declarator (cp_parser*
 						     attrs,
 						     parens_loc);
 		  declarator->attributes = gnu_attrs;
+		  declarator->parameter_pack_p |= pack_expansion_p;
 		  /* Any subsequent parameter lists are to do with
 		     return type, so are not those of the declared
 		     function.  */
@@ -24121,7 +24132,7 @@  cp_parser_direct_declarator (cp_parser*
 
 	  /* If this is the first, we can try a parenthesized
 	     declarator.  */
-	  if (first)
+	  if (first && !pack_expansion_p)
 	    {
 	      bool saved_in_type_id_in_expr_p;
 
@@ -24156,16 +24167,27 @@  cp_parser_direct_declarator (cp_parser*
 	  else
 	    break;
 	}
-      else if ((!first || dcl_kind != CP_PARSER_DECLARATOR_NAMED)
-	       && token->type == CPP_OPEN_SQUARE
-	       && !cp_next_tokens_can_be_attribute_p (parser))
+      else if (((!first || dcl_kind != CP_PARSER_DECLARATOR_NAMED)
+		&& token->type == CPP_OPEN_SQUARE
+		&& !cp_next_tokens_can_be_attribute_p (parser))
+	       || (first
+		   && dcl_kind != CP_PARSER_DECLARATOR_NAMED
+		   && token->type == CPP_ELLIPSIS
+		   && cp_lexer_nth_token_is (parser->lexer, 2, CPP_OPEN_SQUARE)
+		   && cxx_dialect > cxx98
+		   && !cp_nth_tokens_can_be_std_attribute_p (parser, 2)))
 	{
 	  /* Parse an array-declarator.  */
 	  tree bounds, attrs;
+	  bool pack_expansion_p = token->type == CPP_ELLIPSIS;
 
 	  if (ctor_dtor_or_conv_p)
 	    *ctor_dtor_or_conv_p = 0;
 
+	  if (pack_expansion_p)
+	    /* Consume the `...' */
+	    cp_lexer_consume_token (parser->lexer);
+
 	  open_paren = NULL;
 	  first = false;
 	  parser->default_arg_ok_p = false;
@@ -24220,6 +24242,7 @@  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->parameter_pack_p |= pack_expansion_p;
 	}
       else if (first && dcl_kind != CP_PARSER_DECLARATOR_ABSTRACT)
 	{
--- gcc/testsuite/g++.dg/cpp0x/variadic185.C.jj	2024-05-09 15:08:49.070651189 +0200
+++ gcc/testsuite/g++.dg/cpp0x/variadic185.C	2024-05-09 15:07:40.045583153 +0200
@@ -0,0 +1,39 @@ 
+// PR c++/115012
+// { dg-do compile { target { c++11 && c++23_down } } }
+// { dg-final { scan-assembler "_Z3fooILi10EJidEEvDpAT__T0_" } }
+// { dg-final { scan-assembler "_Z3barILi10EiEvPT0_" } }
+// { dg-final { scan-assembler "_Z3bazILi10EJidEEvDpAT__T0_" } }
+// { dg-final { scan-assembler "_Z3quxILi5EJifEEvDpAT__AT__T0_" } }
+
+template <int N, typename ...T>
+void
+foo (T... x[N])
+{
+}
+
+template <int N, typename T>
+void
+bar (T [N])
+{
+}
+
+template <int N, typename ...T>
+void
+baz (T... [N])
+{
+}
+
+template <int N, typename ...T>
+void
+qux (T... [N][N])
+{
+}
+
+void
+corge (int a[10], double b[10], int c[5][5], float d[5][5])
+{
+  foo <10, int, double> (a, b);
+  bar <10, int> (a);
+  baz <10, int, double> (a, b);
+  qux <5, int, float> (c, d);
+}
--- gcc/testsuite/g++.dg/cpp0x/variadic186.C.jj	2024-05-09 16:39:50.409153099 +0200
+++ gcc/testsuite/g++.dg/cpp0x/variadic186.C	2024-05-09 15:37:22.469569809 +0200
@@ -0,0 +1,43 @@ 
+// PR c++/115012
+// { dg-do compile { target { c++11 } } }
+// { dg-final { scan-assembler "_Z3fooIJidEEvDpFT_iE" } }
+// { dg-final { scan-assembler "_Z3barIiEvPFT_iE" } }
+// { dg-final { scan-assembler "_Z3bazIJidEEvDpFT_iE" } }
+
+template <typename ...T>
+void
+foo (T... x (int))
+{
+}
+
+template <typename T>
+void
+bar (T (int))
+{
+}
+
+template <typename ...T>
+void
+baz (T... (int))
+{
+}
+
+int
+f1 (int)
+{
+  return 0;
+}
+
+double
+f2 (int)
+{
+  return 0;
+}
+
+void
+corge ()
+{
+  foo <int, double> (f1, f2);
+  bar <int> (f1);
+  baz <int, double> (f1, f2);
+}