feature #20618 [DI] Make ContainerBuilder::resolveEnvPlaceholders() able to inline the values of referenced env vars. (nicolas-grekas)

This PR was merged into the 3.3-dev branch.

Discussion
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[DI] Make ContainerBuilder::resolveEnvPlaceholders() able to inline the values of referenced env vars.

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Being able to resolve environment variables at compile time as a replacement for `SYMFONY__` special env vars, unlocking their deprecation (see #20100).

Commits
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713b081 [DI] Make ContainerBuilder::resolveEnvPlaceholders() able to inline the values of referenced env vars.

Author: fabpot

DependencyInjection/FrameworkExtension.php

@@ -1248,6 +1248,10 @@ private function registerCacheConfiguration(array $config, ContainerBuilder $con
         if (isset($config['prefix_seed'])) {
             $container->setParameter('cache.prefix.seed', $config['prefix_seed']);
         }
+        if ($container->hasParameter('cache.prefix.seed')) {
+            // Inline any env vars referenced in the parameter
+            $container->setParameter('cache.prefix.seed', $container->resolveEnvPlaceholders($container->getParameter('cache.prefix.seed'), true));
+        }
         foreach (array('doctrine', 'psr6', 'redis') as $name) {
             if (isset($config[$name = 'default_'.$name.'_provider'])) {
                 $container->setAlias('cache.'.$name, new Alias(Compiler\CachePoolPass::getServiceProvider($container, $config[$name]), false));