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package magnolia
import scala.reflect.macros.{runtime, whitebox}
import scala.tools.nsc.Global
/** Workarounds that needs to use `nsc.Global`. */
private[magnolia] object GlobalUtil {
// From Shapeless: https://github.com/milessabin/shapeless/blob/master/core/src/main/scala/shapeless/generic.scala#L698
// Cut-n-pasted (with most original comments) and slightly adapted from
// https://github.com/scalamacros/paradise/blob/c14c634923313dd03f4f483be3d7782a9b56de0e/plugin/src/main/scala/org/scalamacros/paradise/typechecker/Namers.scala#L568-L613
def patchedCompanionRef(c: whitebox.Context)(tpe: c.Type): c.Tree = {
// see https://github.com/scalamacros/paradise/issues/7
// also see https://github.com/scalamacros/paradise/issues/64
val global = c.universe.asInstanceOf[Global]
val typer = c.asInstanceOf[runtime.Context].callsiteTyper.asInstanceOf[global.analyzer.Typer]
val ctx = typer.context
val globalType = tpe.asInstanceOf[global.Type]
val original = globalType.typeSymbol
val owner = original.owner
val companion = original.companion.orElse {
import global.{ abort => aabort, _ }
implicit class PatchedContext(ctx: global.analyzer.Context) {
trait PatchedLookupResult { def suchThat(criterion: Symbol => Boolean): Symbol }
def patchedLookup(name: Name, expectedOwner: Symbol) = new PatchedLookupResult {
override def suchThat(criterion: Symbol => Boolean): Symbol = {
var res: Symbol = NoSymbol
var ctx = PatchedContext.this.ctx
while (res == NoSymbol && ctx.outer != ctx) {
// NOTE: original implementation says `val s = ctx.scope lookup name`
// but we can't use it, because Scope.lookup returns wrong results when the lookup is ambiguous
// and that triggers https://github.com/scalamacros/paradise/issues/64
val s = {
val lookupResult = ctx.scope.lookupAll(name).filter(criterion).toList
lookupResult match {
case Nil => NoSymbol
case List(unique) => unique
case _ => aabort(s"unexpected multiple results for a companion symbol lookup for $original#{$original.id}")
}
}
if (s != NoSymbol && s.owner == expectedOwner)
res = s
else
ctx = ctx.outer
}
res
}
}
}
ctx.patchedLookup(original.name.companionName, owner) suchThat { sym =>
(original.isTerm || sym.hasModuleFlag) && (sym isCoDefinedWith original)
}
}
global.gen.mkAttributedRef(globalType.prefix, companion).asInstanceOf[c.Tree]
}
}
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