diff options
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Implicits.scala | 2 | ||||
| -rw-r--r-- | src/library/scala/Predef.scala | 10 | ||||
| -rw-r--r-- | src/reflect/scala/reflect/internal/Definitions.scala | 3 | ||||
| -rw-r--r-- | src/reflect/scala/reflect/internal/StdNames.scala | 2 | ||||
| -rw-r--r-- | test/files/pos/t7788.scala | 8 |
5 files changed, 19 insertions, 6 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala index 8f5778862d..42687fa7b1 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala @@ -807,7 +807,7 @@ trait Implicits { private def isIneligible(info: ImplicitInfo) = ( info.isCyclicOrErroneous - || isView && (info.sym eq Predef_conforms) + || isView && (info.sym eq Predef_conforms) // as an implicit conversion, Predef.$conforms is a no-op, so exclude it || (!context.macrosEnabled && info.sym.isTermMacro) ) diff --git a/src/library/scala/Predef.scala b/src/library/scala/Predef.scala index 2bde6795e0..faeb1dcbe2 100644 --- a/src/library/scala/Predef.scala +++ b/src/library/scala/Predef.scala @@ -382,9 +382,13 @@ object Predef extends LowPriorityImplicits with DeprecatedPredef { @implicitNotFound(msg = "Cannot prove that ${From} <:< ${To}.") sealed abstract class <:<[-From, +To] extends (From => To) with Serializable private[this] final val singleton_<:< = new <:<[Any,Any] { def apply(x: Any): Any = x } - // not in the <:< companion object because it is also - // intended to subsume identity (which is no longer implicit) - implicit def conforms[A]: A <:< A = singleton_<:<.asInstanceOf[A <:< A] + // The dollar prefix is to dodge accidental shadowing of this method + // by a user-defined method of the same name (SI-7788). + // The collections rely on this method. + implicit def $conforms[A]: A <:< A = singleton_<:<.asInstanceOf[A <:< A] + + @deprecated("Use `implicitly[T <:< U]` or `identity` instead.", "2.11.0") + def conforms[A]: A <:< A = $conforms[A] /** An instance of `A =:= B` witnesses that the types `A` and `B` are equal. * diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala index 645d6aa4ff..73f344345b 100644 --- a/src/reflect/scala/reflect/internal/Definitions.scala +++ b/src/reflect/scala/reflect/internal/Definitions.scala @@ -1429,7 +1429,8 @@ trait Definitions extends api.StandardDefinitions { TypeTagClass -> materializeTypeTag ) lazy val TagSymbols = TagMaterializers.keySet - lazy val Predef_conforms = getMemberMethod(PredefModule, nme.conforms) + lazy val Predef_conforms = (getMemberIfDefined(PredefModule, nme.conforms) + orElse getMemberMethod(PredefModule, "conforms": TermName)) // TODO: predicate on -Xsource:2.10 (for now, needed for transition from M8 -> RC1) lazy val Predef_classOf = getMemberMethod(PredefModule, nme.classOf) lazy val Predef_implicitly = getMemberMethod(PredefModule, nme.implicitly) lazy val Predef_wrapRefArray = getMemberMethod(PredefModule, nme.wrapRefArray) diff --git a/src/reflect/scala/reflect/internal/StdNames.scala b/src/reflect/scala/reflect/internal/StdNames.scala index aad5f32b5f..92245790cf 100644 --- a/src/reflect/scala/reflect/internal/StdNames.scala +++ b/src/reflect/scala/reflect/internal/StdNames.scala @@ -661,7 +661,7 @@ trait StdNames { val classOf: NameType = "classOf" val clone_ : NameType = "clone" val collection: NameType = "collection" - val conforms: NameType = "conforms" + val conforms: NameType = "$conforms" // dollar prefix to avoid accidental shadowing val copy: NameType = "copy" val create: NameType = "create" val currentMirror: NameType = "currentMirror" diff --git a/test/files/pos/t7788.scala b/test/files/pos/t7788.scala new file mode 100644 index 0000000000..81eada962b --- /dev/null +++ b/test/files/pos/t7788.scala @@ -0,0 +1,8 @@ +class Test { + // Predef used to define a method `conforms` to produce the implicit evidence below + // all this does is ensure we don't rename Predef.$conforms back to conforms when $ goes out of fashion + // or that there is some other way of generating the implicit value that witnesses T => U for T <: U + def conforms(x: Int, y: Int) = x < y + def foo[A](implicit ev: Int => A) = ??? + foo[Int] +}
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