[ChrisAbner]

Closes #510

ParameterBag::keys() and all() return the parameters with their own keys, and PHP turns numeric array keys into integers, so ?0=x gives the key 0 as an int on every released symfony/http-foundation version. Symfony 7.4+ documents keys() as list<string>, all() as array<string, mixed> and the iterator as <string, mixed>, and StubFilesExtensionLoader stopped loading ParameterBag.stub from 7.4 on. So a correct is_string($key) guard over those keys is reported as always true, and removing it lets an int reach a string parameter. This PR loads ParameterBag.stub below 8.2.0.0, and the stub now covers all() too (array<mixed>).

Why 8.2: symfony/symfony#66127, merged into 8.2, makes keys() and the iterator cast the keys to string and documents all() as array<mixed>, so from 8.2 on the upstream types match what the code returns and should win, as #481 intends. 8.2 is not released yet (the latest is 8.1.10). Raising the existing < 7.4.0.0 block would also bring back the InputBag and Request stubs, so ParameterBag.stub gets its own condition and the other two keep theirs. The issue suggests < 8.3.0.0, but 8.2 is where the runtime behaviour changes. The all() entry uses the same type as 8.2 upstream.

Verification. An external project (phpstan/phpstan 2.3.4, this extension through a path repository, level 8), with the issue's snippet, the same guard over array_keys($bag->all()), the key type of foreach ($request->query as $key => $value), and the actual keys of Request::create('/search?0=x&78=y&q=z')->query->keys():

symfony/http-foundation	Keys at runtime	keys() before → after	$bag->all() before → after	is_string($key) reported (keys(), all()) before → after
6.4.49	0, 78 are int	list<int|string> → same	array → array<mixed>	no → no
7.4.22	int	list<string> → list<int|string>	array<string, mixed> → array<mixed>	yes → no
8.0.x-dev	int	list<string> → list<int|string>	array<string, mixed> → array<mixed>	yes → no
8.1.10	int	list<string> → list<int|string>	array<string, mixed> → array<mixed>	yes → no
8.2.x-dev	'0', '78' are string	list<string> → same	array<mixed> → same	yes → yes (the guard is redundant there)

On 7.4–8.1 the foreach key goes from string to int|string; on 8.2 it stays string. InputBag::get(), $request->request->get('a', 'x') and $bag->all('foo') give the same types before and after on every version.

tests/Type/Symfony/data/parameter_bag.php asserts the types of keys(), all(), all('foo') and the foreach key. With the suite's symfony/http-foundation 6.4 the stub was already loaded, so only the all() assertions fail without this change; they pass with it, on the highest dependencies (6.4.49) and with --prefer-lowest (5.4.54, PHPStan 2.3.0). phpunit (448 tests), parallel-lint, PHPStan level 8 and phpcs (build-cs) pass.

Not covered: the suite never installs symfony/http-foundation 7.4 or later (dev constraint ^5.4 || ^6.1), so no test reaches the new version condition itself; once #483 widens that constraint, parameter_bag.php covers it as is. InputBag::all() without arguments still has string keys on every Symfony version, because InputBagDynamicReturnTypeExtension builds that type itself; that is older than the 7.4 gate and changing it would affect all versions, so I left it out.