This is the expected and correct output:

Created foo, foo->thing['stuff'] = 1234
Creating Bar, foo->thing['stuff'] = 1234
Created bar, bar->thing2['stuff'] = ABC
Created bar, foo->thing['stuff'] = ABC

Hint: References are not pointers.

So, how do you explain the difference in behaviour when the (should-
be-inert) line in Foo::__construct() is removed?

Also, while I'm perfectly well aware that references are not pointers, 
even calling (for example): $this->thing = array_merge($foo->thing, 
array()); in Bar::__construct() causes $bar->thing to become a 
reference.

If this report _is_ bogus, then:

a) Creating a deep reference (i.e., $this->thing2 =& $this-
>thing['stuff']: in Foo::__construct()) should have no bearing on 
anything; $foo->thing2 is not used beyond that initial assignment.

b) How is one supposed to duplicate the contents of an array given a 
reference to it? Last I heard, the use of ?clone? was only supported 
for objects.

Whilst this report may be, on the face of it, bogus, there is a bug 
here in either case.

My apologies, in my previous follow-up, I meant to write ?$foo->stuff? 
where I wrote ?$foo->thing2?. In my testcase, there's no such property 
as $foo->thing2!

If this bug has been marked as bogus, does it mean it's going to get 
summarily ignored from here on in?

It would be nice if somebody could actually try _running_ the test-case 
instead of dismissing it out of hand; aspects of the behaviour are 
clearly incorrect (notably the inconsistency), even if it's the case 
that my summary of it is wrong.

FYI: I did run your (bogus) testcase.

Okay, let me rephrase, because I'm obviously not being clear about 
something or other.

Line 12 of the testcase is the following:

$this->stuff =& $this->thing['stuff'];

If this line is commented out, the output changes (to my ?expected 
result?). If this line is uncommented, the output is as per your 
?expected result?.

Foo::$stuff is not referenced anywhere (beyond its initial 
declaration) except for this line.

Your statement ?references are not pointers? to me, as an experienced 
C programmer, suggests that under no circumstances, except for the 
assignment of object instances, should the following result in $b 
being a reference to $a:

$b = $a;

In the testcase (tested on PHP 5.2.5 with debugging enabled, and PHP 
5.1.6 with debugging enabled, both command-line and Apache 2 Handler 
SAPIs), line 24 behaves as though it were written:

$this->thing2 =& $foo->thing;

?if, and only if, line 12 is uncommented. Otherwise, it behaves as it 
is written:

$this->thing2 = $foo->thing;

There is NO documented reason why this behaviour should occur.

Now, if you _still_ think this is bogus, I'd really appreciate an 
explanation, with appropriate references to the documentation, as to 
why it's bogus, because if it is I'm evidently a simpleton who can't 
read and I'm now becoming slightly frustrated by both this issue and 
the unhelpfully terse responses to it.

colder@jack /var/cvs/php.net/php5.3-dev $ sapi/cli/php -r '$v = 2; $a = array("k" => &$v); $b = $a; $b["k"]++; echo $v;'
3

When arrays get copied, the elements that are references are kept as references.

Thank you!

That makes perfect sense, and explains what jani meant by ?references 
are not pointers?.