From 05382e2351e1ec6ebfbb50c4df12a2b1410a0b80 Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Sat, 6 Aug 2011 21:53:17 +0000 Subject: Improved structural type error messages, and ot... Improved structural type error messages, and other error message related boosts. Closes SI-4877, review by odersky. --- .../scala/tools/nsc/typechecker/TypeDiagnostics.scala | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) (limited to 'src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala') diff --git a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala index 2c424d17d7..6e0e78e8e2 100644 --- a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala +++ b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala @@ -212,6 +212,13 @@ trait TypeDiagnostics { else if (sym.variance == -1) "contravariant" else "invariant" + // I think this should definitely be on by default, but I need to + // play with it a bit longer. For now it's behind -Xlint. + def explainAlias(tp: Type) = ( + if (!settings.lint.value || (tp eq tp.normalize)) "" + else " (which expands to)\n " + tp.normalize + ) + /** Look through the base types of the found type for any which * might have been valid subtypes if given conformant type arguments. * Examine those for situations where the type error would have been @@ -286,12 +293,12 @@ trait TypeDiagnostics { "" // no elaborable variance situation found } - def foundReqMsg(found: Type, req: Type): String = { - (withDisambiguation(List(), found, req) { - ";\n found : " + found.toLongString + existentialContext(found) + - "\n required: " + req + existentialContext(req) - }) + explainVariance(found, req) - } + def foundReqMsg(found: Type, req: Type): String = ( + withDisambiguation(Nil, found, req)( + ";\n found : " + found.toLongString + existentialContext(found) + explainAlias(found) + + "\n required: " + req + existentialContext(req) + explainAlias(req) + ) + explainVariance(found, req) + ) case class TypeDiag(tp: Type, sym: Symbol) extends Ordered[TypeDiag] { // save the name because it will be mutated until it has been -- cgit v1.2.3