re PR c++/26997 (g++ reports misleading error message when the identifier with error occurs earlier on the same line)

2008-10-29  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c++/26997
cp/
	* parser.c (cp_parser_token_starts_cast_expression): New.
	(cp_parser_cast_expression): Peek the next token to decide whether
	this could be a parenthesized constructor or is definitely an
	actual cast.
testsuite/
	* g++.dg/parse/pr26997.C: New.

From-SVN: r141429

1 files changed, 67 insertions, 10 deletions

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 7596048..40f2a3a 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -5910,6 +5910,60 @@ cp_parser_delete_expression (cp_parser* parser)
   return delete_sanity (expression, NULL_TREE, array_p, global_scope_p);
 }
 
+/* Returns true if TOKEN may start a cast-expression and false
+   otherwise.  */
+
+static bool
+cp_parser_token_starts_cast_expression (cp_token *token)
+{
+  switch (token->type)
+    {
+    case CPP_COMMA:
+    case CPP_SEMICOLON:
+    case CPP_QUERY:
+    case CPP_COLON:
+    case CPP_CLOSE_SQUARE:
+    case CPP_CLOSE_PAREN:
+    case CPP_CLOSE_BRACE:
+    case CPP_DOT:
+    case CPP_DOT_STAR:
+    case CPP_DEREF:
+    case CPP_DEREF_STAR:
+    case CPP_DIV:
+    case CPP_MOD:
+    case CPP_LSHIFT:
+    case CPP_RSHIFT:
+    case CPP_LESS:
+    case CPP_GREATER:
+    case CPP_LESS_EQ:
+    case CPP_GREATER_EQ:
+    case CPP_EQ_EQ:
+    case CPP_NOT_EQ:
+    case CPP_EQ:
+    case CPP_MULT_EQ:
+    case CPP_DIV_EQ:
+    case CPP_MOD_EQ:
+    case CPP_PLUS_EQ:
+    case CPP_MINUS_EQ:
+    case CPP_RSHIFT_EQ:
+    case CPP_LSHIFT_EQ:
+    case CPP_AND_EQ:
+    case CPP_XOR_EQ:
+    case CPP_OR_EQ:
+    case CPP_XOR:
+    case CPP_OR:
+    case CPP_OR_OR:
+      return false;
+
+      /* '[' may start a primary-expression in obj-c++.  */
+    case CPP_OPEN_SQUARE:
+      return c_dialect_objc ();
+
+    default:
+      return true;
+    }
+}
+
 /* Parse a cast-expression.
 
    cast-expression:
@@ -5988,17 +6042,18 @@ cp_parser_cast_expression (cp_parser *parser, bool address_p, bool cast_p)
       /* Restore the saved message.  */
       parser->type_definition_forbidden_message = saved_message;
 
-      /* If ok so far, parse the dependent expression. We cannot be
-	 sure it is a cast. Consider `(T ())'.  It is a parenthesized
-	 ctor of T, but looks like a cast to function returning T
-	 without a dependent expression.  */
-      if (!cp_parser_error_occurred (parser))
-	expr = cp_parser_cast_expression (parser,
-					  /*address_p=*/false,
-					  /*cast_p=*/true);
-
-      if (cp_parser_parse_definitely (parser))
+      /* At this point this can only be either a cast or a
+	 parenthesized ctor such as `(T ())' that looks like a cast to
+	 function returning T.  */
+      if (!cp_parser_error_occurred (parser)
+	  && cp_parser_token_starts_cast_expression (cp_lexer_peek_token
+						     (parser->lexer)))
 	{
+	  cp_parser_parse_definitely (parser);
+	  expr = cp_parser_cast_expression (parser,
+					    /*address_p=*/false,
+					    /*cast_p=*/true);
+
 	  /* Warn about old-style casts, if so requested.  */
 	  if (warn_old_style_cast
 	      && !in_system_header
@@ -6019,6 +6074,8 @@ cp_parser_cast_expression (cp_parser *parser, bool address_p, bool cast_p)
 	  expr = build_c_cast (type, expr);
 	  return expr;
 	}
+      else 
+        cp_parser_abort_tentative_parse (parser);
     }
 
   /* If we get here, then it's not a cast, so it must be a