Michael created FLINK-12300:
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Summary: Unused Import warning with DataStream[Seq[...]]
Key: FLINK-12300
URL: https://issues.apache.org/jira/browse/FLINK-12300
Project: Flink
Issue Type: Bug
Components: API / Scala
Affects Versions: 1.8.0
Reporter: Michael
There is a regression in Flink 1.8.0 compared to 1.7.2 using Scala...
When enabling unused import warnings in *build.sbt*:
{code:java}
scalacOptions ++= Seq("-Xfatal-warnings", "-Ywarn-unused-import")
{code}
...and compiling a file with this content:
{code:java}
package com.example.unusedimportissue
import org.apache.flink.streaming.api.scala._
object ExampleSeqDataStream {
def doubleElement(numbers: DataStream[Int]): DataStream[Seq[Int]] = {
numbers.map(x => Seq(x, x))
}
}
{code}
Then with Flink 1.8.0 this compile issue happens (while with Flink 1.7.2
everything compiles fine):
{noformat}
[error] /path/to/com/example/unusedimportissue/example.scala:1:0: Unused import
[error] package com.example.unusedimportissue
[error] ^
{noformat}
If the result type {{DataStream[Seq[Int]]}} is replaced by {{DataStream[Int]}},
then this issue does not occur, so it is related to the {{Seq[...]}} type.
Maybe a Flink macro is generating an import that is not used, resulting in this
error?
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