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Document the Twig conflict when an application loads its own Twig by Sharawey74 · Pull Request #2688 · simplesamlphp/simplesamlphp · GitHub
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Document the Twig conflict when an application loads its own Twig #2688

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Document the Twig conflict when an application loads its own Twig #2688

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7903a46
Remove deprecated Twig includes from the release autoloader
Sharawey74 Oct 2, 2026
5120624
Document the Twig conflict instead of patching the release autoloader
Sharawey74 Oct 8, 2026
63e75bf
Remove the PHP-FPM pool option from the Twig conflict note
Sharawey74 Oct 9, 2026
d1ca2d7
Correct the Twig conflict note and document the workaround
Sharawey74 Nov 10, 2026
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40 changes: 40 additions & 0 deletions docs/simplesamlphp-sp.md
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Expand Up @@ -277,6 +277,46 @@ session_set_save_handler($handler);
session_start();
```

### Applications that use Twig themselves

SimpleSAMLphp uses [Twig](https://twig.symfony.com/) for its templates. Twig 3
defines a few deprecated global functions in files that its Composer package
always loads. If your application loads Twig itself and SimpleSAMLphp loads its
own copy, those files can be included twice in the same PHP process, and PHP
stops with an error like this, even when both copies are the same version:

```text
PHP Fatal error: Cannot redeclare function twig_cycle()
```

Whether this happens depends on how your application loads Twig:

- **Twig from Composer:** this works, whether SimpleSAMLphp comes from a release
archive or is installed with Composer. Composer records which of these files
it has already included, and both installations of Twig get the same record,
so the files are only loaded once.
- **Twig from an operating system package** (for example
`/usr/share/php/Twig/autoload.php` on Debian): this fails however
SimpleSAMLphp is installed, because the package's autoloader does not share
Composer's record.

SimpleSAMLphp does not use these deprecated functions. If your application
cannot load Twig through Composer, mark the files as already included before
loading SimpleSAMLphp's autoloader. Composer then skips them:

```php
// Tell Composer that Twig's deprecated function files are already loaded.
$GLOBALS['__composer_autoload_files']['89efb1254ef2d1c5d80096acd12c4098'] = true; // twig/twig:src/Resources/core.php
$GLOBALS['__composer_autoload_files']['ffecb95d45175fd40f75be8a23b34f90'] = true; // twig/twig:src/Resources/debug.php
$GLOBALS['__composer_autoload_files']['c7baa00073ee9c61edf148c51917cfb4'] = true; // twig/twig:src/Resources/escaper.php
$GLOBALS['__composer_autoload_files']['f844ccf1d25df8663951193c3fc307c8'] = true; // twig/twig:src/Resources/string_loader.php

require_once('/path/to/simplesamlphp/src/_autoload.php');
```

Composer derives these keys from the package name and the file path, not the
file contents, so they stay the same across Twig 3 releases.

## Support

If you need help to make this work, or want to discuss SimpleSAMLphp with other
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