diff options
Diffstat (limited to 'tests/pos/t1957.scala')
| -rw-r--r-- | tests/pos/t1957.scala | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/tests/pos/t1957.scala b/tests/pos/t1957.scala index 711ce17de..2ac7f0414 100644 --- a/tests/pos/t1957.scala +++ b/tests/pos/t1957.scala @@ -1,3 +1,4 @@ +// See comment at end of file. object Test { abstract class Settings {} @@ -30,8 +31,32 @@ object Test { protected def f: List[commonModuleType] = { - val inputGrists = tools.flatMap(_.inputGrist) // val inputGrists: List[gristType] = - inputGrists.map(_.module) + val inputGrists = tools.flatMap(_.inputGrist) + // This produces an unhygienic closure for _.inputGrist. + // Pickling will log: + // + // [...] pickling reference to as yet undefined value _$1 in method $anonfun + // + // More info can be produced by uncommenting these two lines in + // Namer#valOrDefDefSig: + // + //println(i"lifting $rhsType over $paramss -> $hygienicType = ${tpt.tpe}") + //println(TypeComparer.explained { implicit ctx => hygienicType <:< tpt.tpe }) + // + // Tracing the subtype statement (over 1600+ lines!) shows that the TypeComparer thinks that the + // following subtype judgement is true: + // + // Test.Grist{ + // moduleType <: Test.Module{settingsType = Module.this.settingsType}; + // settingsType <: Module.this.settingsType + // } <:< Test.Grist{moduleType <: _$1.moduleType; settingsType <: _$1.settingsType} + // + // Therefore, a type variable which has the second type as lower bound does not get + // the (hygienic) first type as new lower bound. Clearly something is wrong in the subtype + // derivation here. It would be important to figure out what. + + ??? +// inputGrists.map(_.module) } } |