Low-hanging perf improvements #10462
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- avoid loading shapeless for the sole purpose of having a compile-time type inequality - don't use `sys.env` to avoid some Scala conversions - lazy initialization of fields
hubertp
added
CI: No changelog needed
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| // https://stackoverflow.com/questions/6909053/enforce-type-difference | ||
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| sealed class =!=[A, B] |
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Not that copying this code into our repository would simplify the magic...
| @@ -2226,7 +2226,6 @@ lazy val `runtime-compiler` = | |||
| annotationProcSetting, | |||
| (Test / fork) := true, | |||
| libraryDependencies ++= Seq( | |||
| "com.chuusai" %% "shapeless" % shapelessVersion % "provided", | |||
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I don't see any other usages of shapelessVersion. I guess:
val shapelessVersion = "2.3.10"
should also be removed then.
| @@ -146,7 +145,7 @@ object IRPass { | |||
| */ | |||
| @throws[CompilerError] | |||
| def unsafeAs[T <: Metadata: ClassTag](implicit | |||
| @unused ev: T =:!= Metadata | |||
| @unused ev: T =!= Metadata | |||
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Is this a Scala way of doing Kotlin's reified classes?
Wouldn't it be simpler to just delete the method implicit magic altogether and just pass in the argument explicitly?
Btw. Why is the method called unsafeAs then? Reified classes can be checked during runtime in Kotlin and I see some runtime check here as well.
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The sole purpose of this logic is to ensure at compile time that neither type inferencer nor explicit type argument result in T being Metadata rather than its subclass.
I don't think providing explicit argument to every usage site is better, plus it doesn't prevent incorrect usage this implicit prevents from.
Pull Request Description
type inequality
sys.envto avoid some Scala conversionsImportant Notes
On a slow machine, so easier to spot.
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