FIX: Check if simpleDispatcher() / cachedDispatcher() are already defined.

[sstruk]

Problem : PHP Fatal error: Cannot re-declare FastRoute\simpleDispatcher()

When developing a package ( e.g. in Laravel workbench ) that depends on FastRoute, issue occurs when both main project and package have a dependency on FastRoute.

Issue is that code in functions.php doesn't check if those two functions are already defined, and PHP dies when it tries to include the FastRoute from dev package vendor / FastRoute folder ( as it already is defined in main project vendor / FastRoute ).

[nikic]

Why would that file be included twice? If a project depends on FastRoute twice, composer should still include the bootstrap only once.

[sstruk]

If you check composer.json you'll see

    "autoload": {
    "psr-4": {
      "FastRoute\\": "src/"
    },
    "files": ["src/functions.php"]
  }

And that loads the file on every request, and since project is included on two different locations file gets loaded twice.