Fix phpstan/phpstan#13902: Chaining phpstan-assert fails to assert types

[phpstan-bot]

Summary

When calling methods with @phpstan-assert annotations in a chain (e.g., $o->setA()->setB() where both return $this), neither assertion was recognized. Calling them separately ($o->setA(); $o->setB();) worked correctly.

Changes

• src/Analyser/TypeSpecifier.php - specifyTypesInCondition(): Added recursion into inner method calls when processing a method chain in null context (expression statements). When the outermost method call's assertions are processed and $expr->var is itself a MethodCall, the inner call is also processed and both results are combined. The recursion is guarded to only apply when $expr->var instanceof MethodCall to avoid breaking ImpossibleCheckTypeHelper's rootExpr tracking.

• src/Analyser/TypeSpecifier.php - specifyTypesFromAsserts(): When building the $argsMap['this'] mapping, the code now walks back through the method chain, unwrapping through intermediate method calls whose return type equals the caller's type (indicating the method returns $this). This ensures that assertions like @phpstan-assert int $this->b on the outermost call resolve to the original variable (e.g., $o->b) rather than the intermediate expression (e.g., $o->setA()->b).

Root cause

Two issues combined:

1. Missing recursion: TypeSpecifier::specifyTypesInCondition() only processed the outermost method call's assertions. For $o->setA()->setB(), only setB()'s assertions were applied. The inner setA() call was never examined for its @phpstan-assert annotations.

2. Wrong $this resolution: When setB() was called on $o->setA(), the $this in setB()'s assertion mapped to $o->setA() (the intermediate expression). This created a type narrowing on the expression key $o->setA()->b instead of $o->b, so the narrowing was invisible when accessing $o->b.

Test

Added tests/PHPStan/Analyser/nsrt/bug-13902.php which tests both chained ($o->setA()->setB()) and separate ($o->setA(); $o->setB();) method calls with @phpstan-assert annotations, verifying that property types are correctly narrowed in both cases.

Fixes phpstan/phpstan#13902

[staabm]

I think we need something which does not only work on $context->null()

[ondrejmirtes]

The best solution would be if ExpressionResult (returned by processExprNode) would also contain SpecifiedTypes, effectively merging NodeScopeResolver and TypeSpecifier.

I think that half-measures like this are not worth it.