Fix false positive comparing identical generic types below level 8 - #6392
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Fix false positive comparing identical generic types below level 8#6392calebdw wants to merge 1 commit into
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RuleLevelHelper relaxes the nullability of the accepted type but not of the accepting one, which is what lets a nullable value be passed where a non-nullable one is expected below level 8. TypeTraverser applied that relaxation to generic type arguments as well, so the argument of an accepted Collection<string, int|null> became int while the accepting side kept int|null. Compared invariantly, two identical types then stopped matching and the reported message printed the same type on both sides. Skip the mapper on GenericObjectType and map its children via Type::traverse() instead, which also preserves subclasses through recreate().
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| private function traverseWithoutMapping(Type $type, callable $traverse): Type | ||
| { | ||
| if ($type instanceof GenericObjectType) { | ||
| return $type->traverse($traverse); |
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This looks promising but I don't think it's that easy.
Currently when you have @template-covariant and you're trying to pass Foo<int|null> into Foo<int> below level 8, it doesn't report an error.
But on the other hand, what we're trying to fix is passing @template (invariant) Foo<int|null> into Foo<int|null> below level 8, it SHOULD NOT report an error.
And also, passing Foo<int> into Foo<int|null> should not be allowed for @template below level 8.
Please verify my statements, I'm not sure all of that is still true. And on which levels these start or stop being reported.
That's why in our experiments we were trying to solve it with this #4210
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Hello!
Closes phpstan/phpstan#13876
Closes phpstan/phpstan#12984
Closes phpstan/phpstan#11041
Closes phpstan/phpstan#10698
Closes phpstan/phpstan#9096
RuleLevelHelper relaxes the nullability of the accepted type but not of the accepting one, which is what lets a nullable value be passed where a non-nullable one is expected below level 8. TypeTraverser applied that relaxation to generic type arguments as well, so the argument of an accepted Collection<string, int|null> became int while the accepting side kept int|null. Compared invariantly, two identical types then stopped matching and the reported message printed the same type on both sides.
Map the arguments of a concrete generic type instead of feeding them through the relaxation. A template type keeps going through the regular traversal, as rebuilding it as a plain generic would lose its bound.
Thanks!