Bug #69091 [Com]: assign by reference and math

Edit report at https://bugs.php.net/bug.php?id=69091&edit=1

 ID:                 69091
 Comment by:         cmbecker69 at gmx dot de
 Reported by:        rstoll at tutteli dot ch
 Summary:            assign by reference and math
 Status:             Open
 Type:               Bug
 Package:            PHP Language Specification
 PHP Version:        5.6.6
 Block user comment: N
 Private report:     N

 New Comment:

The language specification further states[1]:

| assignment-expression must be an lvalue, a call to a function
| that returns a value byRef, or a new-expression (see comment below
| regarding this).

However, $a+1 is neither of these, so $a =& ($a + 1) is invalid;
therefore ($a =& $a) + 1 is tried and successfully parsed.

This issue is closely related to #68804[2], BTW.

[1] <https://github.com/php/php-langspec/blob/master/spec/10-expressions.md#byref-assignment>
[2] <https://bugs.php.net/bug.php?id=68804>


Previous Comments:
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[2015-02-20 15:17:06] rstoll at tutteli dot ch

Description:
------------
assign by reference in conjunction with arithmetic does not result in a syntax error as expected. The test script shows two examples. The first one is correct according to the current implementation, but should result in a parser error IMO. The second results in a parser error (how it should be). 

It seems like the parser has a wrong precedence. I think the problem is this line in the grammar:
http://lxr.php.net/xref/PHP_TRUNK/Zend/zend_language_parser.y#777

The langspec does not mention operator precedence explicitly (which should be added IMO) but implicitly the =& operator can be found in the section "Assignment Operator" (https://github.com/php/php-langspec/blob/b1e7a65fb9c985a8114322330468b77fb955cfae/spec/19-grammar.md#assignment-operators)
which is further below than +

Test script:
---------------
$a = &$a + 1;
$a = 1 + &$a;

Expected result:
----------------
parser error in both cases or the precedence explanation needs to be changed. 
Reading the spec I would assume the first line in the code above is equivalent to:
$a = (&$a + 1);
and not
($a = &$a) + 1;





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Edit this bug report at https://bugs.php.net/bug.php?id=69091&edit=1