Use argument types as parameter types for inline closures (#7798)

[leongersen]

Implements #7798. Thank you for your advise, it was very helpful.

The relevant code for this in NodeScopeResolver is this but you won't have to touch that for this feature request, it works in a general sense:

phpstan-src/src/Analyser/NodeScopeResolver.php

Lines 2964 to 2975 in 4b6d964

	if ($passedToType instanceof UnionType) {
	$passedToType = TypeCombinator::union(...array_filter(
	$passedToType->getTypes(),
	static fn (Type $type) => $type->isCallable()->yes(),
	));
	}
	$callableParameters = null;
	$acceptors = $passedToType->getCallableParametersAcceptors($scope);
	if (count($acceptors) === 1) {
	$callableParameters = $acceptors[0]->getParameters();
	}

This unfortunately is not used for this case; $passedToType is only passed to processClosureNode when handling a closure as a function argument:

phpstan-src/src/Analyser/NodeScopeResolver.php

Lines 3223 to 3226 in 4b6d964

	if ($arg->value instanceof Expr\Closure) {
	$this->callNodeCallbackWithExpression($nodeCallback, $arg->value, $scopeToPass, $context);
	$result = $this->processClosureNode($arg->value, $scopeToPass, $nodeCallback, $context, $parameterType ?? null);
	} elseif ($arg->value instanceof Expr\ArrowFunction) {

phpstan-src/src/Analyser/NodeScopeResolver.php

Lines 2220 to 2221 in 4b6d964

	return $this->processClosureNode($expr, $scope, $nodeCallback, $context, null);
	} elseif ($expr instanceof Expr\ClosureUse) {

Because the closure is never the argument (it is the name of the FuncCall), this case is slightly different than for array_map, as the Expr\Closure is never handled by ParametersAcceptorSelector::selectFromArgs (only its ClosureType is).

Please let me know if I misunderstood.

[ondrejmirtes]

This is really nicce and almost perfect! The only thing missing is that you should also test and make sure it works for arrow functions :) Please add another gathered file in NodeScopeResolverTest, but only for PHP_VERSION_ID >= 70400.

[leongersen]

Thanks for the feedback, much appreciated. I've now added support and tests for arrow functions as well.

I've duplicated the logic and added another NodeVisitor, as processArrowFunctionNode duplicates logic from processClosureNode. If you'd like it abstracted I can of course do that.

[ondrejmirtes]

Thank you!