`static(Class<NarrowedTemplateValue>)` does not apply the NarrowedTemplateValue in conditional on instance var

[EmielM]

Bug report

See playground, where I'm trying to typecheck our little ORM abstraction to see if records are backed, meaning we know the ->id is int when IsBackedT is true.

Code snippet that reproduces the problem

https://phpstan.org/r/bfaf491b-c44f-47ce-b6c5-e34c42f7b124

Expected output

A few issues I'm struggling to understand. Could be me, or otherwise some bugs or (ideas for) possible improvements:

• Method DBRecord::newInstance() should return static(DBRecord<IsBackedT of bool>) but returns static(DBRecord<bool>); are these different types?
• It looks like @phpstan-self-out static<true> does narrow the type to static(DBRecord<true>), but then accessing ->id does not use the conditional. Probably because of the static(...) thing, but I don't want to narrow to self<true>. I also tried @phpstan-self-out (static & DBRecord<true>) (which I thought would be the same as static(DBRecord<true>)), no luck
• For assertBacked, using phpstan-self-out is a weird hack, would be better to somehow support the generic narrowing through @phpstan-assert, couldn't get that to work
• It is weird that there is no construct to disallow functions conditionally based on a template type. If it would accept parameters, you could condition those to never. For this case I have @return MyCondition ? void : never, but violations are catched on the next line only. Analog to @phpstan-self-out, perhaps a @phpstan-self-in could be an idea?

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