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author | Jason Zaugg <jzaugg@gmail.com> | 2013-10-07 15:06:22 +0200 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2013-10-07 23:45:31 +0200 |
commit | 8ed7099f7db6a1060a490a594c958ca9a8b41487 (patch) | |
tree | 0ab90bf897c9d323a59465983f771ae931194f31 /test/files/neg | |
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 'test/files/neg')
-rw-r--r-- | test/files/neg/t7899.check | 6 | ||||
-rw-r--r-- | test/files/neg/t7899.scala | 7 |
2 files changed, 13 insertions, 0 deletions
diff --git a/test/files/neg/t7899.check b/test/files/neg/t7899.check new file mode 100644 index 0000000000..febfe76b8a --- /dev/null +++ b/test/files/neg/t7899.check @@ -0,0 +1,6 @@ +t7899.scala:5: error: type mismatch; + found : Int => Int + required: (=> Int) => ? + foo(identity)() + ^ +one error found diff --git a/test/files/neg/t7899.scala b/test/files/neg/t7899.scala new file mode 100644 index 0000000000..f2dea3ab1f --- /dev/null +++ b/test/files/neg/t7899.scala @@ -0,0 +1,7 @@ +object Test { + def foo[B](f: (=> Int) => B): () => B = () => f(0) + + def main(args: Array[String]) { + foo(identity)() + } +} |