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Bug #21820 [CRITICAL] "$arr['foo']" generates bogus E_NOTICE, bc break
Submitted: 2003-01-22 09:19 UTC Modified: 2003-04-25 05:15 UTC
Avg. Score:4.5 ± 0.5
Reproduced:1 of 1 (100.0%)
Same Version:1 (100.0%)
Same OS:0 (0.0%)
From: george at omniti dot com Assigned:
Status: Closed Package: Scripting Engine problem
PHP Version: 4.3.2-RC1 OS:
Private report: No CVE-ID: None
 [2003-01-22 09:19 UTC] george at omniti dot com
I don't think this is a bug, but someone sent it to me via 
email, so I'm proxy-submitting:

Hello George-

I stumbled upon a serious bug in the string parser and it
goes something like this:

  $arr = array('foo' => 'bar');
  print "$arr['foo']";

This used to provide a parse error but now instead we get
this one of level E_NOTICE:

Notice: Undefined index:  'foo' in /tmp/a.php on line 4
/tmp/a.php(4) : Notice - Undefined index:  'foo'

This is a serious problem as it moved an error from
parse to E_NOTICE, fails silently as most have error
reporting turned down, shows a misleading error as foo
is defined, and breaks BC.

Tested latest 4_3 HEAD (4.3.1-dev).  I would try php5
but I get segfault when trying to compile/use it :)

Have a nice day,
Philip Olson

cc: derick


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 [2003-01-22 13:25 UTC] george at omniti dot com
patch up at

patch allows for "$arr['foo']" to be parsed correctly (this 
seems better than disallowing it)
 [2003-01-22 13:43 UTC]
Allowing it would be nice but this topic has come up many times.  Not sure why it's not been implemented though, maybe there are reasons?  I forget them.

One feature request for this:

 [2003-01-22 13:45 UTC] george at omniti dot com
this patch fixes that feature request/bug as well
 [2003-01-22 13:56 UTC]
Point was, maybe there is a reason this was not implemented.

And btw, this is a bug as 'foo' is defined yet the error says it's not.

 [2003-01-22 19:53 UTC]
Anyone remember in what version of PHP this did work? :)
Correct (?) way to do this is:


 $arr = array('foo' => 'bar');
 print "{$arr['foo']}";


Or at least I've started to use that just because of this bug.

 [2003-01-22 20:28 UTC] george at omniti dot com
This bug appeared in 4.3.0 as a result of the lexer changes 
added to ZE1 and ZE2 in november to speed up 
variableinterpolation in strings.  

Previous to 4.3 this was valid:

echo "$a[b]";
echo "$a['b']"; generated a parse error.

The bug manifests itself by turning this parse error into a 
non-sensical E_NOTICE error.

The patch 'fixes' the bug by making 

echo "$a['b']";

work, which has been a pending feature request and seems 
nice (to me), or at least harmless.
 [2003-02-13 12:52 UTC]
Marking as critical.  This is a serious bug as it's subtle and confuses newbies, especially when they/we try to use autoglobals in strings.  This bug fix really needs to make it into 4.3.1
 [2003-02-13 13:04 UTC]
I still maintain that the patch I posted is the right way 
to solve the problem.

$a['b'] is the 'correct' way to access an associative array 
outside of a quoted section, it should at least be allowed 
inside double quotes.  This encourages consisitency within 
the language.
 [2003-02-25 04:50 UTC]
Stig's reply on the mailing list:

Take consistency further, and you wonder should "'a'" === "a"?
No, so why should "$foo['a']" === "$foo[a]"?
The index is already quoted, it's inside the string.
The syntax we're talking about here is supposed to be 
straightforward and simple, and for any kind of tricks we 
recommend the "{$foo['a']}" syntax. IMHO this would bloat the syntax beyond straightforward.


Thus we better keep it like it is now -> wont fix.

 [2003-03-13 14:05 UTC]
This still provides a bogus E_NOTICE, which is the bug.  The feature request of "$arr['foo']" working is #15677 not #21820

To simply fix the bug, 4.3.2 should provide a parse error just like 4.2.3 does.

A/the discussion took place on the zend2 mailing list, which can be seen around here:

Thread title: "[Zend Engine 2] fix for bug 21820"

 [2003-04-23 02:34 UTC]
It's been couple of weeks (almost :) since Andi promised
to fix this..maybe this will wake him up..

 [2003-04-25 01:14 UTC]
de-assign. :)

 [2003-04-25 05:15 UTC]
This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at
In case this was a documentation problem, the fix will show up soon at

In case this was a website problem, the change will show
up on the site and on the mirror sites in short time.
Thank you for the report, and for helping us make PHP better.

 [2003-07-08 19:39 UTC] coda at bobandgeorge dot com
Argh; I was relying on the way that worked before, and when my server admin upgraded to 4.3.2, all my scripts stopped working. >_<
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