Summary

When an object has an optional property (e.g., object{containers?: array<int>}) and the property is checked via is_array($obj->containers ?? null), the property should be narrowed from optional to required in the truthy branch. Previously, it stayed optional.

Changes

• Modified src/Analyser/TypeSpecifier.php in the createForExpr method: when a Coalesce expression is simplified to its left-side PropertyFetch (because the narrowed type excludes the right side), also emit a HasPropertyType constraint on the object variable — mirroring what isset() already does for property fetches.

Root cause

In createForExpr, when is_array($obj->prop ?? null) is true, the Coalesce $obj->prop ?? null is correctly simplified to $obj->prop (since null is not an array). The property expression itself was narrowed to array<int>, but the object was not told that the property definitely exists. The isset() handler already did this by adding HasPropertyType to the object, but the Coalesce simplification path in createForExpr did not.

Test

Added tests/PHPStan/Analyser/nsrt/bug-11610.php with two cases:

1. is_array($obj->prop ?? null) — the bug case, now correctly narrows to object{containers: array<int>}
2. isset($obj->prop) || is_array($obj->prop) — already working, included for completeness

Fixes phpstan/phpstan#11610