Chaining type pack breaks type inference and fails to compile

[stephencelis]

Description

When a type with a parameter pack returns a new type with a parameter pack, the type checking appears to fail to resolve the type when chained into another call.

Reproduction

struct S<T, each U> {
  func combine<V, each W>(_ other: S<V, repeat each W>) -> S<T, repeat each U, V, repeat each W> {
    fatalError()
  }

  func inspect(_: (T, repeat each U) -> Void) -> Self {
    self
  }
}

func f() {
  S<Int>().inspect { print($0) }

  let s1 = S<Int>()
  s1.inspect { print($0) }

  // ✅ This works
  let s2 = S<Int>().combine(S<Double>())
  s2.inspect { print($0, $1) }

  // 🛑 Could not infer pack element #0 from context
  // 🛑 Could not infer pack element #1 from context
  // 🛑 Could not infer pack element #2 from context
  S<Int>().combine(S<Double>()).inspect { print($0, $1) }
}

Expected behavior

I expect the line to compile since it's just combining the statements before it into a single expression

Environment

swift-driver version: 1.115.1 Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
Target: arm64-apple-macosx15.0

Additional information

No response