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Fabien Potencier
dd0bd0ffbc
This PR was merged into the 3.x branch.
Discussion
----------
Release destructuring temporaries after assignment
The compiled destructuring code kept the right-hand side alive in a hidden local until the end of rendering, wasting memory on large arrays and iterators. The temporary is now cleared as part of the compiled expression.
The way it works:
For this Twig expression:
```twig
{% do {name, email: address} = user %}
```
The previous generated expression was conceptually:
```php
[$context["name"], $context["address"]] = [
getAttribute($_v0 = $context["user"], "name"),
getAttribute($_v0, "email"),
];
```
The branch now generates:
```php
[
[$context["name"], $context["address"]] = [
getAttribute($_v0 = $context["user"], "name"),
getAttribute($_v0, "email"),
],
$_v0 = null,
][0]
```
The important wrapper is:
```php
[$originalExpression, $_v0 = null][0]
```
PHP evaluates array elements from left to right:
1. The original destructuring assignment runs.
2. The temporary variable is set to `null`, releasing its reference.
3. `[0]` returns the result of the original expression.
This preserves Twig’s rule that a destructuring expression returns its right-hand value.
Commits
-------
c459ef0bdd Release destructuring temporaries after assignment
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