Fix phpstan/phpstan#11978: Ordering of Intersections matters for method calls, first matching wins

[phpstan-bot]

Summary

When calling a method on an intersection type like ViewA&ViewB, PHPStan always used the first type's method signature for parameter validation. This meant that ViewA&ViewB and ViewB&ViewA could produce different errors, violating PHP's guarantee that intersection type ordering is irrelevant.

Changes

• Modified src/Reflection/Type/IntersectionTypeMethodReflection.php: In getVariants(), instead of always using $this->methods[0] for parameters, find the method with the most parameters across all intersection members and use that
• Added regression test tests/PHPStan/Rules/Methods/data/bug-11978.php and test method in CallMethodsRuleTest.php

Root cause

IntersectionTypeMethodReflection::getVariants() mapped over $this->methods[0]->getVariants() to build the combined variant, taking the parameters from the first method in the intersection. For an intersection ViewA&ViewB where ViewA::render() has 0 parameters and ViewB::render(string $foo = '') has 1 optional parameter, the first-wins approach used ViewA's 0-parameter signature, causing a false positive when calling render($foo).

The fix selects the method with the most parameters, since any concrete implementation of the intersection must satisfy all interface contracts, meaning the widest parameter list is always valid to call.

Test

Added tests/PHPStan/Rules/Methods/data/bug-11978.php with two intersection types (ViewA&ViewB and ViewB&ViewA) where both call render() with one argument. Neither should produce an error.

Fixes phpstan/phpstan#11978

[VincentLanglet]

There is multiple occurence of

$this->methods[0]

in this class.

Extract this in a private method to use it.

Also add a cache on the selected method.

[phpstan-bot]

Background make tests also completed successfully. All tests pass, static analysis is clean, and the commit has been pushed.

[VincentLanglet]

Add a SHORT phpdoc to comment getMethodWithMostParameters

[phpstan-bot]

Tests passed as well. All done — the PHPDoc has been added, verified with both make phpstan and make tests, and pushed.

[staabm]

append these line to the test:

$c = $this->view1->render($foo, $foo);
$d = $this->view2->render($foo, $foo);
$e = $this->view1->render();
$f = $this->view2->render();

and adjust expected errors in tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

[phpstan-bot]

Background make tests also completed successfully. All done — the review changes are committed and pushed.

[staabm]

needs conflict resolution and rebase. otherwise LGTM.