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re PR c++/54891 ([C++11] lambda-expression and explicit type conversion (cast notation))

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/cp
2014-06-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/54891
	* parser.c (cp_parser_tokens_start_cast_expression): In C++11
	a '[' can also start a primary-expression.
	(cp_parser_cast_expression): Parse a cast-expression only tentatively
	when cp_parser_tokens_start_cast_expression returns -1.

/testsuite
2014-06-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/54891
	* g++.dg/cpp0x/lambda/lambda-cast1.C: New.

From-SVN: r212162
This commit is contained in:
Paolo Carlini 2014-06-30 18:30:50 +00:00 committed by Paolo Carlini
parent 6e7ceb171d
commit 17adeaa773
4 changed files with 71 additions and 29 deletions
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8
gcc/cp/ChangeLog
View File

@ -1,3 +1,11 @@
2014-06-30 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/54891
* parser.c (cp_parser_tokens_start_cast_expression): In C++11
a '[' can also start a primary-expression.
(cp_parser_cast_expression): Parse a cast-expression only tentatively
when cp_parser_tokens_start_cast_expression returns -1.
2014-06-30 Jason Merrill <jason@redhat.com>
PR c++/61539

80
gcc/cp/parser.c
View File

@ -4109,6 +4109,7 @@ complain_flags (bool decltype_p)
this
( expression )
id-expression
lambda-expression (C++11)
GNU Extensions:
@ -7621,10 +7622,10 @@ cp_parser_delete_expression (cp_parser* parser)
tf_warning_or_error);
}
/* Returns true if TOKEN may start a cast-expression and false
otherwise. */
/* Returns 1 if TOKEN may start a cast-expression and, in C++11,
isn't '[', -1 if TOKEN is '[' in C++11, 0 otherwise. */
static bool
static int
cp_parser_tokens_start_cast_expression (cp_parser *parser)
{
cp_token *token = cp_lexer_peek_token (parser->lexer);
@ -7667,7 +7668,7 @@ cp_parser_tokens_start_cast_expression (cp_parser *parser)
case CPP_OR:
case CPP_OR_OR:
case CPP_EOF:
return false;
return 0;
case CPP_OPEN_PAREN:
/* In ((type ()) () the last () isn't a valid cast-expression,
@ -7675,12 +7676,15 @@ cp_parser_tokens_start_cast_expression (cp_parser *parser)
return cp_lexer_peek_nth_token (parser->lexer, 2)->type
!= CPP_CLOSE_PAREN;
/* '[' may start a primary-expression in obj-c++. */
/* '[' may start a primary-expression in obj-c++ and in C++11,
as a lambda-expression, eg, '(void)[]{}'. */
case CPP_OPEN_SQUARE:
if (cxx_dialect >= cxx11)
return -1;
return c_dialect_objc ();
default:
return true;
return 1;
}
}
@ -7705,7 +7709,7 @@ cp_parser_cast_expression (cp_parser *parser, bool address_p, bool cast_p,
{
tree type = NULL_TREE;
tree expr = NULL_TREE;
bool cast_expression_p;
int cast_expression = 0;
const char *saved_message;
/* There's no way to know yet whether or not this is a cast.
@ -7728,6 +7732,7 @@ cp_parser_cast_expression (cp_parser *parser, bool address_p, bool cast_p,
will commit to the parse at that point, because we cannot
undo the action that is done when creating a new class. So,
then we cannot back up and do a postfix-expression.
Another tricky case is the following (c++/29234):
struct S { void operator () (); };
@ -7746,20 +7751,30 @@ cp_parser_cast_expression (cp_parser *parser, bool address_p, bool cast_p,
we are dealing with an unary-expression, a postfix-expression
or something else.
Yet another tricky case, in C++11, is the following (c++/54891):
(void)[]{};
The issue is that usually, besides the case of lambda-expressions,
the parenthesized type-id cannot be followed by '[', and, eg, we
want to parse '(C ())[2];' in parse/pr26997.C as unary-expression.
Thus, if cp_parser_tokens_start_cast_expression returns -1, below
we don't commit, we try a cast-expression, then an unary-expression.
Save tokens so that we can put them back. */
cp_lexer_save_tokens (parser->lexer);
/* We may be looking at a cast-expression. */
cast_expression_p
= (cp_parser_skip_to_closing_parenthesis (parser, false, false,
/*consume_paren=*/true)
&& cp_parser_tokens_start_cast_expression (parser));
if (cp_parser_skip_to_closing_parenthesis (parser, false, false,
/*consume_paren=*/true))
cast_expression
= cp_parser_tokens_start_cast_expression (parser);
/* Roll back the tokens we skipped. */
cp_lexer_rollback_tokens (parser->lexer);
/* If we aren't looking at a cast-expression, simulate an error so
that the call to cp_parser_parse_definitely below will fail. */
if (!cast_expression_p)
that the call to cp_parser_error_occurred below returns true. */
if (!cast_expression)
cp_parser_simulate_error (parser);
else
{
@ -7780,30 +7795,37 @@ cp_parser_cast_expression (cp_parser *parser, bool address_p, bool cast_p,
function returning T. */
if (!cp_parser_error_occurred (parser))
{
cp_parser_parse_definitely (parser);
/* Only commit if the cast-expression doesn't start with '[' in
C++11, which may or may not start a lambda-expression. */
if (cast_expression > 0)
cp_parser_commit_to_topmost_tentative_parse (parser);
expr = cp_parser_cast_expression (parser,
/*address_p=*/false,
/*cast_p=*/true,
/*decltype_p=*/false,
pidk);
/* Warn about old-style casts, if so requested. */
if (warn_old_style_cast
&& !in_system_header_at (input_location)
&& !VOID_TYPE_P (type)
&& current_lang_name != lang_name_c)
warning (OPT_Wold_style_cast, "use of old-style cast");
if (cp_parser_parse_definitely (parser))
{
/* Warn about old-style casts, if so requested. */
if (warn_old_style_cast
&& !in_system_header_at (input_location)
&& !VOID_TYPE_P (type)
&& current_lang_name != lang_name_c)
warning (OPT_Wold_style_cast, "use of old-style cast");
/* Only type conversions to integral or enumeration types
can be used in constant-expressions. */
if (!cast_valid_in_integral_constant_expression_p (type)
&& cp_parser_non_integral_constant_expression (parser,
NIC_CAST))
return error_mark_node;
/* Only type conversions to integral or enumeration types
can be used in constant-expressions. */
if (!cast_valid_in_integral_constant_expression_p (type)
&& cp_parser_non_integral_constant_expression (parser,
NIC_CAST))
return error_mark_node;
/* Perform the cast. */
expr = build_c_cast (input_location, type, expr);
return expr;
/* Perform the cast. */
expr = build_c_cast (input_location, type, expr);
return expr;
}
}
else
cp_parser_abort_tentative_parse (parser);

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2014-06-30 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/54891
* g++.dg/cpp0x/lambda/lambda-cast1.C: New.
2014-06-30 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/51400

7
gcc/testsuite/g++.dg/cpp0x/lambda/lambda-cast1.C Normal file
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@ -0,0 +1,7 @@
// PR c++/54891
// { dg-do compile { target c++11 } }
int main()
{
(void)[]{};
}