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| author | Jason Zaugg <jzaugg@gmail.com> | 2013-10-07 15:06:22 +0200 |
|---|---|---|
| committer | Jason Zaugg <jzaugg@gmail.com> | 2013-10-07 23:45:31 +0200 |
| commit | 8ed7099f7db6a1060a490a594c958ca9a8b41487 (patch) | |
| tree | 0ab90bf897c9d323a59465983f771ae931194f31 /src | |
| parent | 90a312669b37d6e3e3f08685953ded24759e6102 (diff) | |
| download | scala-8ed7099f7db6a1060a490a594c958ca9a8b41487.tar.gz scala-8ed7099f7db6a1060a490a594c958ca9a8b41487.tar.bz2 scala-8ed7099f7db6a1060a490a594c958ca9a8b41487.zip | |
SI-7899 Don't infer by-name types during, e.g. eta-expansion
Given:
def id[A](a: A): A = a
def foo(f: (=> Int) => Int) = ()
foo(id)
We eta-expanded `id` and inferred `A` to be `=> Int` to satisfy the
expected type set forth by the formal parameter `f`.
We really shouldn't go about inferring types that we can't *write*.
Our attempt to do so led promptly into a `ClassCastException` in the
enclosed test.
This commit:
- drops by-name-ness during `inferExprInstance`
- tests that this results in a type error for the reported bug
(neg/t7899)
- tests that a method with a by-name parameter can still be
eta expanded to match function with a corresponding by-name
parameter (run/t7899)
- discovers the same latent CCE in pos/t7584
- now that would be a type error
- so we compensate by using placeholder functions rather than
eta-expansion.
- and move that that test to `run` for good measure.
Diffstat (limited to 'src')
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Infer.scala | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala index 03f680525c..ccf4a5e46f 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala @@ -913,12 +913,13 @@ trait Infer extends Checkable { val targs = exprTypeArgs(tvars, tparams, treeTp, pt, useWeaklyCompatible) def infer_s = map3(tparams, tvars, targs)((tparam, tvar, targ) => s"$tparam=$tvar/$targ") mkString "," printTyping(tree, s"infer expr instance from pt=$pt, $infer_s") + def targsStrict = if (targs eq null) null else targs mapConserve dropByName if (keepNothings || (targs eq null)) { //@M: adjustTypeArgs fails if targs==null, neg/t0226 - substExpr(tree, tparams, targs, pt) + substExpr(tree, tparams, targsStrict, pt) List() } else { - val AdjustedTypeArgs.Undets(okParams, okArgs, leftUndet) = adjustTypeArgs(tparams, tvars, targs) + val AdjustedTypeArgs.Undets(okParams, okArgs, leftUndet) = adjustTypeArgs(tparams, tvars, targsStrict) def solved_s = map2(okParams, okArgs)((p, a) => s"$p=$a") mkString "," def undet_s = leftUndet match { case Nil => "" |