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author | Adriaan Moors <adriaan.moors@typesafe.com> | 2013-04-04 16:51:41 -0700 |
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committer | Adriaan Moors <adriaan.moors@typesafe.com> | 2013-04-08 23:01:09 -0700 |
commit | e7aadd00392a512ddcf53396d489f0f17bfac231 (patch) | |
tree | ff62223bed6f9beafd97bd8bbb383adff5c54e8e /src/compiler | |
parent | 53e031f55386d131b1aaa5fb93ee1a3ac6bce646 (diff) | |
download | scala-e7aadd00392a512ddcf53396d489f0f17bfac231.tar.gz scala-e7aadd00392a512ddcf53396d489f0f17bfac231.tar.bz2 scala-e7aadd00392a512ddcf53396d489f0f17bfac231.zip |
SI-7330 better error when pattern isn't a value
Somehow an applied type managed to sneak past the type checker in pattern mode.
Patterns must be values, though.
`case C[_] =>` was probably meant to be `case _: C[_] =>`
Advice is dispensed accordingly. (Generalizing the existing advice machinery.)
Diffstat (limited to 'src/compiler')
3 files changed, 30 insertions, 28 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala index 4bf7f78167..49049f110d 100644 --- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala +++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala @@ -589,6 +589,10 @@ trait ContextErrors { setError(tree) } + // typedPattern + def PatternMustBeValue(pat: Tree, pt: Type) = + issueNormalTypeError(pat, s"pattern must be a value: $pat"+ typePatternAdvice(pat.tpe.typeSymbol, pt.typeSymbol)) + // SelectFromTypeTree def TypeSelectionFromVolatileTypeError(tree: Tree, qual: Tree) = { val hiBound = qual.tpe.bounds.hi @@ -920,33 +924,10 @@ trait ContextErrors { def IncompatibleScrutineeTypeError(tree: Tree, pattp: Type, pt: Type) = issueNormalTypeError(tree, "scrutinee is incompatible with pattern type" + foundReqMsg(pattp, pt)) - def PatternTypeIncompatibleWithPtError2(pat: Tree, pt1: Type, pt: Type) = { - def errMsg = { - val sym = pat.tpe.typeSymbol - val clazz = sym.companionClass - val addendum = ( - if (sym.isModuleClass && clazz.isCaseClass && (clazz isSubClass pt1.typeSymbol)) { - // TODO: move these somewhere reusable. - val typeString = clazz.typeParams match { - case Nil => "" + clazz.name - case xs => xs map (_ => "_") mkString (clazz.name + "[", ",", "]") - } - val caseString = ( - clazz.caseFieldAccessors - map (_ => "_") // could use the actual param names here - mkString (clazz.name + "(", ",", ")") - ) - ( - "\nNote: if you intended to match against the class, try `case _: " + - typeString + "` or `case " + caseString + "`" - ) - } - else "" - ) - "pattern type is incompatible with expected type"+foundReqMsg(pat.tpe, pt) + addendum - } - issueNormalTypeError(pat, errMsg) - } + def PatternTypeIncompatibleWithPtError2(pat: Tree, pt1: Type, pt: Type) = + issueNormalTypeError(pat, + "pattern type is incompatible with expected type"+ foundReqMsg(pat.tpe, pt) + + typePatternAdvice(pat.tpe.typeSymbol, pt1.typeSymbol)) def PolyAlternativeError(tree: Tree, argtypes: List[Type], sym: Symbol, err: PolyAlternativeErrorKind.ErrorType) = { import PolyAlternativeErrorKind._ diff --git a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala index 9376cb5237..4950a7efef 100644 --- a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala +++ b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala @@ -286,6 +286,24 @@ trait TypeDiagnostics { ) } + def typePatternAdvice(sym: Symbol, ptSym: Symbol) = { + val clazz = if (sym.isModuleClass) sym.companionClass else sym + val caseString = + if (clazz.isCaseClass && (clazz isSubClass ptSym)) + ( clazz.caseFieldAccessors + map (_ => "_") // could use the actual param names here + mkString (s"`case ${clazz.name}(", ",", ")`") + ) + else + "`case _: " + (clazz.typeParams match { + case Nil => "" + clazz.name + case xs => xs map (_ => "_") mkString (clazz.name + "[", ",", "]") + })+ "`" + + "\nNote: if you intended to match against the class, try "+ caseString + + } + case class TypeDiag(tp: Type, sym: Symbol) extends Ordered[TypeDiag] { // save the name because it will be mutated until it has been // distinguished from the other types in the same error message diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 34ba8b46f9..7169f93f2b 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -5697,7 +5697,10 @@ trait Typers extends Modes with Adaptations with Tags { // as a compromise, context.enrichmentEnabled tells adaptToMember to go ahead and enrich, // but arbitrary conversions (in adapt) are disabled // TODO: can we achieve the pattern matching bit of the string interpolation SIP without this? - typingInPattern(context.withImplicitsDisabledAllowEnrichment(typed(tree, PATTERNmode, pt))) + typingInPattern(context.withImplicitsDisabledAllowEnrichment(typed(tree, PATTERNmode, pt))) match { + case tpt if tpt.isType => PatternMustBeValue(tpt, pt); tpt + case pat => pat + } } /** Types a (fully parameterized) type tree */ |