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author | Jason Zaugg <jzaugg@gmail.com> | 2014-01-27 10:29:28 +0100 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2014-01-27 10:44:48 +0100 |
commit | 327eea839e97e1d7cac92aa9cd61e3338d12cb12 (patch) | |
tree | 27c96fc40658a947216b61fab6b6da4956c6cdbd /src/compiler | |
parent | a5b0fc49e517d1c63d22f9909ac9bed0552ed466 (diff) | |
download | scala-327eea839e97e1d7cac92aa9cd61e3338d12cb12.tar.gz scala-327eea839e97e1d7cac92aa9cd61e3338d12cb12.tar.bz2 scala-327eea839e97e1d7cac92aa9cd61e3338d12cb12.zip |
Prohibit views targeting AnyVal
Library changes in Scala 2.10 mean that we are left with the
unfortunate situation of admitting:
scala> "": AnyVal
res0: AnyVal =
We already have explicit checks in place to prevent views
targeting `AnyRef`. This commit balances this out by prohibiting
`AnyVal`, as well.
The enclosed test shows that this case is now prevented. If multiple
implicits views are applicable, the ambiguity error is still raised;
these check comes right at the end. Maybe that ought to be changed,
but I don't think it matters too much.
I've also disabled this prohibition under -Xsource:2.10.
Diffstat (limited to 'src/compiler')
-rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Implicits.scala | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala index 06a1e21e8b..9564d6a632 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala @@ -137,10 +137,6 @@ trait Implicits { private val improvesCache = perRunCaches.newMap[(ImplicitInfo, ImplicitInfo), Boolean]() private val implicitSearchId = { var id = 1 ; () => try id finally id += 1 } - private def isInvalidConversionTarget(tpe: Type): Boolean = tpe match { - case Function1(_, out) => AnyRefClass.tpe <:< out - case _ => false - } private def isInvalidConversionSource(tpe: Type): Boolean = tpe match { case Function1(in, _) => in <:< NullClass.tpe case _ => false @@ -629,7 +625,8 @@ trait Implicits { // for instance, if we have `class C[T]` and `implicit def conv[T: Numeric](c: C[T]) = ???` // then Scaladoc will give us something of type `C[T]`, and it would like to know // that `conv` is potentially available under such and such conditions - case tree if isImplicitMethodType(tree.tpe) && !isScalaDoc => applyImplicitArgs(tree) + case tree if isImplicitMethodType(tree.tpe) && !isScalaDoc => + applyImplicitArgs(tree) case tree => tree } case _ => fallback @@ -1361,11 +1358,17 @@ trait Implicits { if (context.ambiguousErrors) context.issueAmbiguousError(AmbiguousImplicitTypeError(tree, msg)) } - if (isInvalidConversionTarget(pt)) { - maybeInvalidConversionError("the result type of an implicit conversion must be more specific than AnyRef") - result = SearchFailure + pt match { + case Function1(_, out) => + def prohibit(sym: Symbol) = if (sym.tpe <:< out) { + maybeInvalidConversionError(s"the result type of an implicit conversion must be more specific than ${sym.name}") + result = SearchFailure + } + prohibit(AnyRefClass) + if (settings.isScala211) prohibit(AnyValClass) + case _ => false } - else if (settings.isScala211 && isInvalidConversionSource(pt)) { + if (settings.isScala211 && isInvalidConversionSource(pt)) { maybeInvalidConversionError("an expression of type Null is ineligible for implicit conversion") result = SearchFailure } |