Backend backport2

[DarkDimius]

The most important bit is fix for erasure, that was emitting such code:

def tailRec(x: Int): Unit = {
  if scala.Int.unbox(x).<(0) then {
    x
    ()
  } else {
    println(scala.Int.box(x))
    C.tailRec(scala.Int.unbox(x).-(1))
  }
}

[DarkDimius]

@odersky lets get this merged, it fixes several issues that trigger failures in checker.

[DarkDimius]

@odersky @gzm0 please review

[gzm0]

LGTM

[odersky]

I'm OK with the rationale you have given for flags naming.

[DarkDimius]

ping @odersky
Please have a look. I've incorporated all comments.

[odersky]

t.resultType isRef dn.Unit

[DarkDimius]

Do I understand correctly that this is just shorter way to do same test?
Or are they actually different?

[odersky]

In this case it's just shorter, but in general isRef is more robust. I flagged it because it's important to be consistent everywhere. Otherwise the next person will choose one randomly depending on what idiom saw previously.

[odersky]

Otherwise, LGTM

[retronym]

Not sure if it matters in Dotty, but in scalac these should be def-s, not vals. Why? Subsequent runs of the compiler might recompile Array (this happens if you navigate to its sources in Scala IDE, for example), which would result in new symbols for its members.

That's why I split out RunDefinitions in scalac, so we could have correctness and speed.

[DarkDimius]

For Dotty definitions are part of context and I would say that in case discarding is required, the better approach would be to discard context itself.

[odersky]

Agreed we should do the same thing. (Keep them as lazyvals but break them
out into a new class) It's planned by has not been done yet. - Martin

On Tue, May 6, 2014 at 4:11 PM, Jason Zaugg [email protected]:

In src/dotty/tools/dotc/core/Definitions.scala:

@@ -168,6 +170,10 @@ class Definitions {
List(AnyClass.typeRef), EmptyScope)
lazy val SeqClass: ClassSymbol = ctx.requiredClass("scala.collection.Seq")
lazy val ArrayClass: ClassSymbol = ctx.requiredClass("scala.Array")

• lazy val Array_apply = ctx.requiredMethod(ArrayClass, nme.apply)
• lazy val Array_update = ctx.requiredMethod(ArrayClass, nme.update)
• lazy val Array_length = ctx.requiredMethod(ArrayClass, nme.length)
• lazy val Array_clone = ctx.requiredMethod(ArrayClass, nme.clone_)

Not sure if it matters in Dotty, but in scalac these should be def-s, not
vals. Why? Subsequent runs of the compiler might recompile Array (this
happens if you navigate to its sources in Scala IDE, for example), which
would result in new symbols for its members.

That's why I split out RunDefinitions in scalac, so we could have
correctness and speed.

—
Reply to this email directly or view it on GitHubhttps://github.com//pull/124/files#r12325734
.

Martin Odersky

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[DarkDimius]

Martin, why do you need a new class for this? Isn't Definitions itself a class that can be discarded with context holding it.