Type inference for ContainerInterface::getParameter()

[mglaman]

Problem

ContainerDynamicReturnTypeExtension handles get() and has() but not getParameter(). Calling $container->getParameter('app.root') currently returns mixed (or whatever the native PHPStan type is) instead of the known parameter type.

For example, app.root is defined as a string parameter in core.services.yml:

parameters:
  app.root: ''

But $container->getParameter('app.root') cannot be inferred as string.

Proposed solution

Build a parameter map from the parameters: sections of service YAMLs in DrupalAutoloader (currently only the services: section is processed), then add a getParameter branch to ContainerDynamicReturnTypeExtension that resolves known parameter names to their types.

Related

• Discovered while cleaning up dead code in Move phpstan_fixtures test data to tests/src/Rules/data #974 — DrupalServiceDefinition::getType() had a SplString workaround that was unreachable because app.root is a parameter, not a service.