Syntax error with array access in string interpolation

[mpesari]

I have only used this library through another library, but here's a reproducible code:

$ composer require opis/closure

<?php

require_once __DIR__ . '/vendor/autoload.php';

use Opis\Closure\SerializableClosure;

$object = new SerializableClosure(function (): string {
    $a = new \ArrayObject(['foo' => 'bar']);

    return "$a[foo]";
});

$function = unserialize(serialize($object));

var_dump($function());

Result (version 3.5.5):

PHP Parse error:  syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE), expecting '-' or identifier (T_STRING) or variable (T_VARIABLE) or number (T_NUM_STRING) in closure://function (): string {
    $a = new \ArrayObject(['foo' => 'bar']);

    return "$a[\foo]";
} on line 5

Result (commit 82cc21f):

string(3) "bar"

I think the problematic commit is c17ece0

Of course a workaround is to "fix" all interpolations like this with

return "{$a['foo']}";

[GrahamCampbell]

You actually need to always put those single quotes in. The other code you have will generate a warning saying constant 'foo' undefined, treated as string, in PHP 5 and 7, and in PHP 8 will be a hard error.

[GrahamCampbell]

So, this is actually not a bug, and it is doing the correct thing, to escape the constant to the global namespace with a slash.

[mpesari]

AFAIK string interpolation has different rules, e.g. theres two are different:

$a = ['foo' => 'bar'];

print $a[foo]; // references a  nonexistant constant, emits a warning
print "$a[foo]"; // "knows" the context, this does not emit a warning

See https://www.php.net/manual/en/language.types.string.php Example 10 which uses this syntax.

I tried it with a PHP 8 Docker image too:

$ docker run --rm -it keinos/php8-jit
Interactive shell

php > print phpversion();
8.0.0-dev
php > $a = ['foo' => 'bar'];
php > print "$a[foo]";
bar
php > print $a[foo];

Warning: Uncaught Error: Undefined constant 'foo' in php shell code:1
Stack trace:
#0 {main}
  thrown in php shell code on line 1

[GrahamCampbell]

Ah, yes. You are right! Hmmm. There is a bug here then. 👍

[n00dl3]

Hello there,
I have experienced troubles with string interpolations too, but that does not only occur with arrays. I created a repo with some tests :

https://github.com/n00dl3/opis-closure-tests

I also tried with @abdrzakoxa PR (branch abdrzakoxa-pr on the test repo), but it only fixes simple array syntax.

Maybe I should open a new issue ?

[sorinsarca]

Yes, please open a new issue.
Meanwhile I'll check to see where the problem is.

It would have been very helpful to put those tests directly inside opis/closure :)

[sorinsarca]

Ok, I've found the problem, a fix is coming in the next minutes.

[n00dl3]

It would have been very helpful to put those tests directly inside opis/closure :)

Yeah, sorry, I started with a single test case and it grew up very quickly...

[sorinsarca]

String interpolation error was solved in 85fec0b
A new version will be released soon.

This issue (with array access) is not solved yet.

[abdrzakoxa]

Hello @sorinsarca
How about my PR, it solves this issue!

[sorinsarca]

@abdrzakoxa I'm looking at that PR right now.