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Adopt scala's scheme for root import hiding #1901

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Merged
merged 1 commit into from
Jan 16, 2017
Merged

Adopt scala's scheme for root import hiding #1901

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1 change: 1 addition & 0 deletions compiler/src/dotty/tools/dotc/core/Definitions.scala
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Expand Up @@ -747,6 +747,7 @@ class Definitions {
else if (ctx.settings.YnoPredef.value) StaticRootImportFns
else StaticRootImportFns ++ PredefImportFns

lazy val ShadowableImportNames = Set("Predef", "DottyPredef").map(_.toTermName)
lazy val RootImportTypes = RootImportFns.map(_())

/** Modules whose members are in the default namespace and their module classes */
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23 changes: 13 additions & 10 deletions compiler/src/dotty/tools/dotc/typer/ImportInfo.scala
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Expand Up @@ -15,17 +15,20 @@ object ImportInfo {
val selectors = untpd.Ident(nme.WILDCARD) :: Nil
def expr = tpd.Ident(refFn())
def imp = tpd.Import(expr, selectors)
new ImportInfo(imp.symbol, selectors, isRootImport = true)
new ImportInfo(imp.symbol, selectors, None, isRootImport = true)
}
}

/** Info relating to an import clause
* @param sym The import symbol defined by the clause
* @param selectors The selector clauses
* @param rootImport true if this is one of the implicit imports of scala, java.lang
* or Predef in the start context, false otherwise.
* @param sym The import symbol defined by the clause
* @param selectors The selector clauses
* @param symNameOpt Optionally, the name of the import symbol. None for root imports.
* Defined for all explicit imports from ident or select nodes.
* @param isRootImport true if this is one of the implicit imports of scala, java.lang,
* scala.Predef or dotty.DottyPredef in the start context, false otherwise.
*/
class ImportInfo(symf: => Symbol, val selectors: List[untpd.Tree], val isRootImport: Boolean = false)(implicit ctx: Context) {
class ImportInfo(symf: => Symbol, val selectors: List[untpd.Tree],
symNameOpt: Option[TermName], val isRootImport: Boolean = false)(implicit ctx: Context) {

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You could put a if (isRootImport) assert(symNameOpt.isEmpty) here to enforce what the documentation says.

lazy val sym = symf

Expand Down Expand Up @@ -105,11 +108,11 @@ class ImportInfo(symf: => Symbol, val selectors: List[untpd.Tree], val isRootImp
*/
lazy val unimported: Symbol = {
lazy val sym = site.termSymbol
val hasMaskingSelector = selectors exists {
case Thicket(_ :: Ident(nme.WILDCARD) :: Nil) => true
case _ => false
def maybeShadowsRoot = symNameOpt match {
case Some(symName) => defn.ShadowableImportNames.contains(symName)
case None => false
}
if (hasMaskingSelector && defn.RootImportTypes.exists(_.symbol == sym)) sym
if (maybeShadowsRoot && defn.RootImportTypes.exists(_.symbol == sym)) sym
else NoSymbol
}

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11 changes: 8 additions & 3 deletions compiler/src/dotty/tools/dotc/typer/Namer.scala
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Expand Up @@ -373,8 +373,13 @@ class Namer { typer: Typer =>
}

/** A new context that summarizes an import statement */
def importContext(sym: Symbol, selectors: List[Tree])(implicit ctx: Context) =
ctx.fresh.setImportInfo(new ImportInfo(sym, selectors))
def importContext(imp: Import, sym: Symbol)(implicit ctx: Context) = {
val impNameOpt = imp.expr match {
case ref: RefTree => Some(ref.name.asTermName)
case _ => None
}
ctx.fresh.setImportInfo(new ImportInfo(sym, imp.selectors, impNameOpt))
}

/** A new context for the interior of a class */
def inClassContext(selfInfo: DotClass /* Should be Type | Symbol*/)(implicit ctx: Context): Context = {
Expand Down Expand Up @@ -423,7 +428,7 @@ class Namer { typer: Typer =>
setDocstring(pkg, stat)
ctx
case imp: Import =>
importContext(createSymbol(imp), imp.selectors)
importContext(imp, createSymbol(imp))
case mdef: DefTree =>
val sym = enterSymbol(createSymbol(mdef))
setDocstring(sym, origStat)
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/typer/Typer.scala
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Expand Up @@ -1588,7 +1588,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
case (imp: untpd.Import) :: rest =>
val imp1 = typed(imp)
buf += imp1
traverse(rest)(importContext(imp1.symbol, imp.selectors))
traverse(rest)(importContext(imp, imp1.symbol))
case (mdef: untpd.DefTree) :: rest =>
mdef.removeAttachment(ExpandedTree) match {
case Some(xtree) =>
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