`track` doesn't work anymore due to non-local returns

[anatoliykmetyuk]

If you set this flag to true and try to compile the compiler, you'll get a bunch of errors as follows:

[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Applications.scala:944:6
[error] 944 |      return errorTree(tree, "invalid pattern")
[error]     |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]     |(This would be an error under strict mode)

Context:

  def typedTypeApply(tree: untpd.TypeApply, pt: Type)(implicit ctx: Context): Tree = track("typedTypeApply") {
    if (ctx.mode.is(Mode.Pattern)) {
      return errorTree(tree, "invalid pattern")
    }
   /*...*/

track is defined as follows.

7 errors of this kind overall

[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Applications.scala:944:6
[error] 944 |      return errorTree(tree, "invalid pattern")
[error]     |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]     |(This would be an error under strict mode)
[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Typer.scala:374:8
[error] 374 |        return tree.withType(pt)
[error]     |        ^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]     |(This would be an error under strict mode)
[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Typer.scala:376:8
[error] 376 |        return typed(desugar.patternVar(tree), pt)
[error]     |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]     |(This would be an error under strict mode)
[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Typer.scala:382:6
[error] 382 |      return tree.withType(defn.RootPackage.termRef)
[error]     |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]     |(This would be an error under strict mode)
[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Typer.scala:412:8
[error] 412 |        return ref(defn.XMLTopScopeModule.termRef)
[error]     |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]     |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]     |(This would be an error under strict mode)
[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Typer.scala:1510:6
[error] 1510 |      return EmptyTree
[error]      |      ^^^^^^^^^^^^^^^^
[error]      |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]      |(This would be an error under strict mode)
[error] -- Error: /Users/anatolii/Projects/dotty/dotty/compiler/src/dotty/tools/dotc/typer/Typer.scala:1582:43
[error] 1582 |    if (!cls.info.isInstanceOf[ClassInfo]) return EmptyTree.assertingErrorsReported
[error]      |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]      |Non local returns are deprecated; use scala.util.control.NonLocalReturns instead
[error]      |(This would be an error under strict mode)
[error] 7 errors found

[nicolasstucki]

The error is at least correct. When track is disabled the inlining optimizes the closure away as intended. We should see how hard would it be to refactor the code to not have those returns.

[odersky]

I think track is no longer relevant and we should drop it. A simple counter (using Stats.record) is enough in all places where track is used.

track also keeps a runtime stack that can be inspected every second with -Yheart-beat, but this is so coarse-grained that nobody looks at it anymore.