[Sema] Descriptor for argument of PreCheckFunctionBuilderRequest

[rintaro]

Follow-up to #32946 (comment)

[rintaro]

@hamishknight @CodaFi I thought this is effectively NFC. But it crashes test/Constraints/function_builder.swift with

Assertion failed: (!isRecording && "Probably not a good idea to allow nested recording"), function replay, file /Users/rintaro/Repositories/swift-oss/swift/lib/AST/Evaluator.cpp, line 451.

What am I doing wrong?

[rintaro]

@CodaFi I suppose the code you mentioned is in evaluator::DependencyRecorder::record, right? That doesn't resolve the crash. BTW, the assertion is in the one in evaluator::DependencyRecorder::replay https://github.com/apple/swift/blob/7b14c1dad735cbd357c739fae59a116b7d2249ce/lib/AST/Evaluator.cpp#L448-L452

[hamishknight]

It sounds like the call to getBody() is firing off a request in the equality and hashing functions while we're handling request dependencies. I'm not sure if we want to support this kind of re-entrant evaluation as it might cause iterator invalidation (not just for dependency tracking, but also things like the evaluator's internal cache).

Perhaps we should call getBody() when the descriptor is constructed and store it as a property? At least it's still encapsulated rather than being a direct input of the request.

[rintaro]

@swift-ci Please smoke test

[hamishknight]

LGTM!

[rintaro]

Windows: