I found a similar bug on bugzilla [1], apparently specification and
real-world implementation just doesn't match. Since our grammar for
do-while is broken anyway [2], it's now the perfect to time to decide
how to fix the grammar:
1) Be strict and make it compliant to the specification (Flex compiler
behaviour)
2) Be more loose and make it similar to the implementation in browsers
A bit more formal:
1) Semicolon with ASI
DoWhileStatement ::= "do" Statement() "while" "(" Expression ")" ";"
2) Optional semicolon without ASI
DoWhileStatement ::= "do" Statement() "while" "(" Expression ")" (";")?
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=238945
[2] http://jira.openlaszlo.org/jira/browse/LPP-9719
On 1/29/2011 9:00 PM, P T Withington wrote:
At least in our parser, it looks like StatementList and Statement cooperate to
allow you to put certain statements together without an intervening semicolon.
Surely an error in our grammar. The fact that other JS's allow it makes me
think that it might be a bug in the specification grammar.
On 2011-01-29, at 12:23, André Bargull wrote:
Can anyone shed some lights on automatic semicolon insertion (ASI) and the
do-while statement?
Consider this function declaration:
function foo () {do {} while(0)(0)}
I'd expect a syntax error, because ASI does not apply in this case (cf. 7.9
ECMAScript3/5), but all major browsers I've tested with (Firefox, Opera,
Safari, IE) accept that function. Compiling the function declaration with the
Flex compiler generated a syntax error just as expected. Note: I've used the
plain html- resp. as-file for testing. Our parser accepts the declaration, too,
but it will also generate non-ambiguous code, therefore I wanted to use plain
files to verify our parser works correctly.
Generated code from our compiler:
function foo () {
/* -*- file: #3 -*- */
do {
} while (0);
/* -*- file: #3 -*- */
0
}
<asi-dowhile.lzx><asi_dowhile.as><asi-dowhile.html>
