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Fix #2512: Implicit keyword not allowed on return types #2523

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Merged
merged 3 commits into from
May 29, 2017
Merged

Fix #2512: Implicit keyword not allowed on return types #2523

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b63b3c2
Fix #2512: Implicit keyword not allowed on return types
biboudis May 24, 2017
43b6fe6
Restore signature of syntaxError
biboudis May 24, 2017
3db3f1b
Replace if with case and drop extra condition
biboudis May 24, 2017
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10 changes: 9 additions & 1 deletion compiler/src/dotty/tools/dotc/parsing/Parsers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -730,11 +730,16 @@ object Parsers {
def typ(): Tree = {
val start = in.offset
val isImplicit = in.token == IMPLICIT
var isImplicitFun = false
if (isImplicit) in.nextToken()
def functionRest(params: List[Tree]): Tree =
atPos(start, accept(ARROW)) {
val t = typ()
if (isImplicit) new ImplicitFunction(params, t) else Function(params, t)
if (isImplicit) {
isImplicitFun = true
new ImplicitFunction(params, t)
}
else Function(params, t)
}
val t =
if (in.token == LPAREN) {
Expand Down Expand Up @@ -771,6 +776,9 @@ object Parsers {
}
else infixType()

if (isImplicit && !isImplicitFun && in.token != ARROW)
syntaxError("Types with implicit keyword can only be function types", Position(start, start + nme.IMPLICITkw.asSimpleName.length))
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Why asSimpleName?

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@biboudis biboudis May 24, 2017 •
edited
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Just to get the length. Any alternative way?

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It is fine


in.token match {
case ARROW => functionRest(t :: Nil)
case FORSOME => syntaxError(ExistentialTypesNoLongerSupported()); t
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I think you can avoid the isImplicitFun logic and simply change the next line to:

 case _ => 
    if (isImplicit) syntaxError("Types with implicit keyword can only be function types", start)
    t

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Even if not, it will eliminate the in.token != ARROW

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10 changes: 10 additions & 0 deletions tests/neg/i2512.scala
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@@ -0,0 +1,10 @@

object Test {

def foo0(): implicit Int => Int = ???
val foo01: implicit (String, Int) => Int = ???

def foo1(f: Int => implicit Int): Int = ??? // error
def foo2(): implicit Int = ??? // error
def foo3(): Int => implicit Int = ??? // error
}