diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/typechecker')
3 files changed, 39 insertions, 4 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala index 7ecc2be9be..2472f63993 100644 --- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala +++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala @@ -408,11 +408,28 @@ trait ContextErrors { setError(tree) } - def MissingParameterTypeError(fun: Tree, vparam: ValDef, pt: Type) = + def MissingParameterTypeError(fun: Tree, vparam: ValDef, pt: Type, withTupleAddendum: Boolean) = { + def issue(what: String) = { + val addendum: String = fun match { + case Function(params, _) if withTupleAddendum => + val funArity = params.length + val example = analyzer.exampleTuplePattern(params map (_.name)) + (pt baseType FunctionClass(1)) match { + case TypeRef(_, _, arg :: _) if arg.typeSymbol == TupleClass(funArity) && funArity > 1 => + sm"""| + |Note: The expected type requires a one-argument function accepting a $funArity-Tuple. + | Consider a pattern matching anoynmous function, `{ case $example => ... }`""" + case _ => "" + } + case _ => "" + } + issueNormalTypeError(vparam, what + addendum) + } if (vparam.mods.isSynthetic) fun match { case Function(_, Match(_, _)) => MissingParameterTypeAnonMatchError(vparam, pt) - case _ => issueNormalTypeError(vparam, "missing parameter type for expanded function " + fun) - } else issueNormalTypeError(vparam, "missing parameter type") + case _ => issue("missing parameter type for expanded function " + fun) + } else issue("missing parameter type") + } def MissingParameterTypeAnonMatchError(vparam: Tree, pt: Type) = issueNormalTypeError(vparam, "missing parameter type for expanded function\n"+ diff --git a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala index 695a1e2e24..b801b644fb 100644 --- a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala +++ b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala @@ -109,6 +109,22 @@ trait TypeDiagnostics { case x => x.toString } + /** + * [a, b, c] => "(a, b, c)" + * [a, B] => "(param1, param2)" + * [a, B, c] => "(param1, ..., param2)" + */ + final def exampleTuplePattern(names: List[Name]): String = { + val arity = names.length + val varPatterNames: Option[List[String]] = sequence(names map { + case name if nme.isVariableName(name) => Some(name.decode) + case _ => None + }) + def parenthesize(a: String) = s"($a)" + def genericParams = (Seq("param1") ++ (if (arity > 2) Seq("...") else Nil) ++ Seq(s"param$arity")) + parenthesize(varPatterNames.getOrElse(genericParams).mkString(", ")) + } + def alternatives(tree: Tree): List[Type] = tree.tpe match { case OverloadedType(pre, alternatives) => alternatives map pre.memberType case _ => Nil diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 6d799b0098..4973346eff 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -2906,6 +2906,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper else if (argpts.lengthCompare(numVparams) != 0) WrongNumberOfParametersError(fun, argpts) else { + var issuedMissingParameterTypeError = false foreach2(fun.vparams, argpts) { (vparam, argpt) => if (vparam.tpt.isEmpty) { vparam.tpt.tpe = @@ -2923,7 +2924,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper } case _ => } - MissingParameterTypeError(fun, vparam, pt) + MissingParameterTypeError(fun, vparam, pt, withTupleAddendum = !issuedMissingParameterTypeError) + issuedMissingParameterTypeError = true ErrorType } if (!vparam.tpt.pos.isDefined) vparam.tpt setPos vparam.pos.focus |