[Bug c++/18126] New: sizeof compound-literal not parsed correctly

["jsm28 at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

The C++ parser fails to parse sizeof compound-literal correctly.  For example,

int x = sizeof (int) { 1 };

receives the error

t.C:1: error: expected %<,%> or %<;%> before '{' token

As shown in the grammar for GNU extensions in comments in cp/parser.c,
compound literals are considered postfix-expressions as they are in C99,
so they are valid arguments to sizeof.  Just as the parser deals with
cast-expressions beginning with a parenthesised type name being either
casts or compound literals, so it needs to avoid committing too early
to a particular parse in the case of sizeof.  My new C parser handles
this case correctly, as has the old one since

2001-01-24  Joseph S. Myers  <jsm28@cam.ac.uk>

        * c-parse.in (cast_expr): Move compound literals from here ...
        (primary): ... to here.  Use standard terminology "compound
        literal" instead of "constructor expression".

The same issue applies to alignof as applies to sizeof.  Since the C++
parser - unlike the C parser and the pre-3.4 C++ parser - accepts
general unary expressions as typeof operands (despite the ambiguity)
rather than just parenthesised expressions, it also applies to typeof.

-- 
           Summary: sizeof compound-literal not parsed correctly
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jsm28 at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18126