From 251c2b9313728bbac5e47ee096b65d1183624650 Mon Sep 17 00:00:00 2001 From: Jason Zaugg Date: Wed, 30 Oct 2013 18:42:56 +0100 Subject: SI-7944 FOUND: stray undetermined type params in vicinity of implicits Implicit search created a nested Context into which the results of its typechecking, namely, errors and undetermined type parameters (roughly: those inferred as Nothing) are stashed. The code the drives the process was checking for errors, but discarded those undetermined type parameters. This commit copies them from the child context to the parent, which lets `Typer#adapt` to get to: else if (hasUndetsInMonoMode) { // (9) assert(!context.inTypeConstructorAllowed, context) //@M instantiatePossiblyExpectingUnit(tree, mode, pt) } Our lost TypeVar has found its way home! The reward for which is being instantiated, based on another type inference session adapting the expression's type to the expected type. --- test/files/pos/t7944.scala | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 test/files/pos/t7944.scala (limited to 'test/files') diff --git a/test/files/pos/t7944.scala b/test/files/pos/t7944.scala new file mode 100644 index 0000000000..2fe2c5866d --- /dev/null +++ b/test/files/pos/t7944.scala @@ -0,0 +1,24 @@ +class M[+A, +B] + +object Test { + implicit class EitherOps[A, B](self: Either[A, B]) { + def disjunction: M[A, B] = null + } + + def foo = { + val l: Either[Int, Nothing] = Left[Int, Nothing](1) + + var ok = EitherOps(l).disjunction + + val runawayTypeVar = l.disjunction + + // reported bug: + // found : M[Int,B]; required: M[Int,Nothing] + val assign: M[Int, Nothing] = runawayTypeVar + + // variations on the theme, all failed before similarly. + val assign1: M[Int, Nothing] = {val temp = runawayTypeVar; temp} + val assign2: M[Int, String] = runawayTypeVar + val assign3: M[Int, Nothing] = {val temp = Left(1).disjunction; temp} + } +} -- cgit v1.2.3