Function php_class_output_dir 

pub fn php_class_output_dir(config: &ResolvedCrateConfig) -> String

The directory alef generate writes the PHP userland classes into, relative to the repository root.

[crates.php.stubs] output wins, then the resolved [crates.output] php path, then the split-layout default — the same precedence generate_public_api and generate_bindings apply when they place the emitted files.