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Fix #6725: Parsing of poly function with parenthesized body #6726

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Merged
merged 1 commit into from
Jun 22, 2019
Merged

Fix #6725: Parsing of poly function with parenthesized body #6726

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4 changes: 3 additions & 1 deletion compiler/src/dotty/tools/dotc/ast/Desugar.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1410,7 +1410,9 @@ object desugar {
}

def makePolyFunction(targs: List[Tree], body: Tree): Tree = body match {
case Function(vargs, res) =>
case Parens(body1) =>
makePolyFunction(targs, body1)
case Function(vargs, res) =>
// TODO: Figure out if we need a `PolyFunctionWithMods` instead.
val mods = body match {
case body: FunctionWithMods => body.mods
Expand Down
26 changes: 16 additions & 10 deletions compiler/src/dotty/tools/dotc/parsing/Parsers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -864,6 +864,12 @@ object Parsers {
*/
def toplevelTyp(): Tree = rejectWildcardType(typ())

private def isFunction(tree: Tree): Boolean = tree match {
case Parens(tree1) => isFunction(tree1)
case _: Function => true
case _ => false
}

/** Type ::= FunType
* | HkTypeParamClause ‘=>>’ Type
* | MatchType
Expand Down Expand Up @@ -946,11 +952,11 @@ object Parsers {
val arrowOffset = in.skipToken()
val body = toplevelTyp()
atSpan(start, arrowOffset) {
body match {
case _: Function => PolyFunction(tparams, body)
case _ =>
syntaxError("Implementation restriction: polymorphic function types must have a value parameter", arrowOffset)
Ident(nme.ERROR.toTypeName)
if (isFunction(body))
PolyFunction(tparams, body)
else {
syntaxError("Implementation restriction: polymorphic function types must have a value parameter", arrowOffset)
Ident(nme.ERROR.toTypeName)
}
}
} else { accept(TLARROW); typ() }
Expand Down Expand Up @@ -1381,11 +1387,11 @@ object Parsers {
val arrowOffset = accept(ARROW)
val body = expr()
atSpan(start, arrowOffset) {
body match {
case _: Function => PolyFunction(tparams, body)
case _ =>
syntaxError("Implementation restriction: polymorphic function literals must have a value parameter", arrowOffset)
errorTermTree
if (isFunction(body))
PolyFunction(tparams, body)
else {
syntaxError("Implementation restriction: polymorphic function literals must have a value parameter", arrowOffset)
errorTermTree
}
}
case _ =>
Expand Down
4 changes: 4 additions & 0 deletions tests/run/polymorphic-functions.scala
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Expand Up @@ -90,4 +90,8 @@ object Test extends App {
}
val s = [T] => (t: T) => given (st: Show[T]) => st.show(t)
assert(s(23) == "23")

// Parens handling
val tt1: [T] => (T => T) = [T] => (x: T) => x
val tt2: [T] => T => T = [T] => ((x: T) => x)
}