Can't branch on compiletime.testing.typeChecks

[bishabosha]

minimized code

import scala.compiletime.testing.typeChecks
import scala.compiletime.error

inline def assertDoesNotCompile(inline code: String): Unit = {
  if (typeChecks(code)) {
    error("Type-checking succeeded unexpectedly.")
  } else {
  }
}

val test1 = assertDoesNotCompile("1")
val test2 = assertDoesNotCompile("1.noSuchMethod")

test1 behaves correctly.

expectation

test2 should be unit, but it is a compiletime error.

To get the correct behaviour, this macro works:

def typeChecksOrErrImpl(code: String) given (qctx: QuoteContext): Expr[Unit] = {
  import qctx.tasty._
  if (typing.typeChecks(code)) {
    error("Type-checking succeeded unexpectedly.", rootPosition)
    '{}
  } else {
    '{}
  }
}

[nicolasstucki]

In general you should use inline if if you what to make sure the condition of the if is constant folded.

  inline if (typeChecks(code)) {
    error("Type-checking succeeded unexpectedly.")
  } else {
  }

[nicolasstucki]

But #7129 makes the original code work.