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author | Jason Zaugg <jzaugg@gmail.com> | 2014-01-27 10:29:28 +0100 |
---|---|---|
committer | Jason Zaugg <jzaugg@gmail.com> | 2014-01-27 10:44:48 +0100 |
commit | 327eea839e97e1d7cac92aa9cd61e3338d12cb12 (patch) | |
tree | 27c96fc40658a947216b61fab6b6da4956c6cdbd | |
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.
-rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Implicits.scala | 21 | ||||
-rw-r--r-- | test/files/neg/no-implicit-to-anyref-any-val.check | 34 | ||||
-rw-r--r-- | test/files/neg/no-implicit-to-anyref-any-val.scala (renamed from test/files/neg/no-implicit-to-anyref.scala) | 4 | ||||
-rw-r--r-- | test/files/neg/no-implicit-to-anyref.check | 22 | ||||
-rw-r--r-- | test/files/pos/implicit-anyval-2.10.flags | 1 | ||||
-rw-r--r-- | test/files/pos/implicit-anyval-2.10.scala | 3 |
6 files changed, 54 insertions, 31 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 } diff --git a/test/files/neg/no-implicit-to-anyref-any-val.check b/test/files/neg/no-implicit-to-anyref-any-val.check new file mode 100644 index 0000000000..5953e1bd6d --- /dev/null +++ b/test/files/neg/no-implicit-to-anyref-any-val.check @@ -0,0 +1,34 @@ +no-implicit-to-anyref-any-val.scala:11: error: the result type of an implicit conversion must be more specific than AnyRef + 1: AnyRef + ^ +no-implicit-to-anyref-any-val.scala:17: error: type mismatch; + found : Any + required: AnyRef + (null: Any): AnyRef + ^ +no-implicit-to-anyref-any-val.scala:21: error: type mismatch; + found : AnyVal + required: AnyRef + (0: AnyVal): AnyRef + ^ +no-implicit-to-anyref-any-val.scala:27: error: type mismatch; + found : Test.AV + required: AnyRef +Note that AV extends Any, not AnyRef. +Such types can participate in value classes, but instances +cannot appear in singleton types or in reference comparisons. + new AV(0): AnyRef + ^ +no-implicit-to-anyref-any-val.scala:30: error: the result type of an implicit conversion must be more specific than AnyVal + "": AnyVal + ^ +no-implicit-to-anyref-any-val.scala:32: error: type mismatch; + found : Object + required: AnyVal +Note that implicit conversions are not applicable because they are ambiguous: + both method ArrowAssoc in object Predef of type [A](self: A)ArrowAssoc[A] + and method Ensuring in object Predef of type [A](self: A)Ensuring[A] + are possible conversion functions from Object to AnyVal + new Object() : AnyVal + ^ +6 errors found diff --git a/test/files/neg/no-implicit-to-anyref.scala b/test/files/neg/no-implicit-to-anyref-any-val.scala index 3e3d373e38..f5daf541af 100644 --- a/test/files/neg/no-implicit-to-anyref.scala +++ b/test/files/neg/no-implicit-to-anyref-any-val.scala @@ -26,4 +26,8 @@ object Test { locally { new AV(0): AnyRef } + + "": AnyVal + + new Object() : AnyVal } diff --git a/test/files/neg/no-implicit-to-anyref.check b/test/files/neg/no-implicit-to-anyref.check deleted file mode 100644 index fe417ad8b0..0000000000 --- a/test/files/neg/no-implicit-to-anyref.check +++ /dev/null @@ -1,22 +0,0 @@ -no-implicit-to-anyref.scala:11: error: the result type of an implicit conversion must be more specific than AnyRef - 1: AnyRef - ^ -no-implicit-to-anyref.scala:17: error: type mismatch; - found : Any - required: AnyRef - (null: Any): AnyRef - ^ -no-implicit-to-anyref.scala:21: error: type mismatch; - found : AnyVal - required: AnyRef - (0: AnyVal): AnyRef - ^ -no-implicit-to-anyref.scala:27: error: type mismatch; - found : Test.AV - required: AnyRef -Note that AV extends Any, not AnyRef. -Such types can participate in value classes, but instances -cannot appear in singleton types or in reference comparisons. - new AV(0): AnyRef - ^ -four errors found diff --git a/test/files/pos/implicit-anyval-2.10.flags b/test/files/pos/implicit-anyval-2.10.flags new file mode 100644 index 0000000000..94c8056747 --- /dev/null +++ b/test/files/pos/implicit-anyval-2.10.flags @@ -0,0 +1 @@ +-Xsource:2.10 diff --git a/test/files/pos/implicit-anyval-2.10.scala b/test/files/pos/implicit-anyval-2.10.scala new file mode 100644 index 0000000000..3082af73b8 --- /dev/null +++ b/test/files/pos/implicit-anyval-2.10.scala @@ -0,0 +1,3 @@ +object Test { + "": AnyVal // newly prohibited in 2.11, allowed under -Xsourse:2.10 +}
\ No newline at end of file |