Merge pull request #3605 from gkossakowski/issue/SI-8372

SI-8372: unspliceable type printed in error message

5 files changed, 233 insertions, 3 deletions

diff --git a/bincompat-backward.whitelist.conf b/bincompat-backward.whitelist.conf
index 9e93c32c70..10c1da59b8 100644
--- a/bincompat-backward.whitelist.conf
+++ b/bincompat-backward.whitelist.conf
@@ -4,4 +4,103 @@ filter {
     # "scala.concurrent.impl"
     # "scala.reflect.runtime"
   ]
+  // see SI-8372
+  problems=[
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofChar.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofChar.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofByte.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofByte.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofShort.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofShort.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofLong.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofLong.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofInt.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofInt.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip3"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip3"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofFloat.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofFloat.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofBoolean.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofBoolean.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofRef.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofRef.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofUnit.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofUnit.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofDouble.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofDouble.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    }
+  ]
 }
\ No newline at end of file
diff --git a/bincompat-forward.whitelist.conf b/bincompat-forward.whitelist.conf
index 9e93c32c70..96994f8969 100644
--- a/bincompat-forward.whitelist.conf
+++ b/bincompat-forward.whitelist.conf
@@ -4,4 +4,103 @@ filter {
     # "scala.concurrent.impl"
     # "scala.reflect.runtime"
   ]
-}
\ No newline at end of file
+  // see SI-8372
+  problems=[
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofChar.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofChar.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofByte.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofByte.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofShort.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofShort.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofLong.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofLong.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofInt.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofInt.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip3"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps.unzip3"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofFloat.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofFloat.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofBoolean.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofBoolean.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofRef.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofRef.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofUnit.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofUnit.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofDouble.unzip"
+        problemName=IncompatibleMethTypeProblem
+    },
+    {
+        matchName="scala.collection.mutable.ArrayOps#ofDouble.unzip3"
+        problemName=IncompatibleMethTypeProblem
+    }
+  ]
+}
diff --git a/src/library/scala/collection/mutable/ArrayOps.scala b/src/library/scala/collection/mutable/ArrayOps.scala
index e342e134b4..00491ef20e 100644
--- a/src/library/scala/collection/mutable/ArrayOps.scala
+++ b/src/library/scala/collection/mutable/ArrayOps.scala
@@ -114,10 +114,16 @@ trait ArrayOps[T] extends Any with ArrayLike[T, Array[T]] with CustomParalleliza
    *  @tparam T2    the type of the second half of the element pairs
    *  @param asPair an implicit conversion which asserts that the element type
    *                of this Array is a pair.
+   *  @param ct1    a class tag for T1 type parameter that is required to create an instance
+   *                of Array[T1]
+   *  @param ct2    a class tag for T2 type parameter that is required to create an instance
+   *                of Array[T2]
    *  @return       a pair of Arrays, containing, respectively, the first and second half
    *                of each element pair of this Array.
    */
-  def unzip[T1: ClassTag, T2: ClassTag](implicit asPair: T => (T1, T2)): (Array[T1], Array[T2]) = {
+  // implementation NOTE: ct1 and ct2 can't be written as context bounds because desugared
+  // implicits are put in front of asPair parameter that is supposed to guide type inference
+  def unzip[T1, T2](implicit asPair: T => (T1, T2), ct1: ClassTag[T1], ct2: ClassTag[T2]): (Array[T1], Array[T2]) = {
     val a1 = new Array[T1](length)
     val a2 = new Array[T2](length)
     var i = 0
@@ -137,10 +143,19 @@ trait ArrayOps[T] extends Any with ArrayLike[T, Array[T]] with CustomParalleliza
    *  @tparam T3      the type of the third of three elements in the triple
    *  @param asTriple an implicit conversion which asserts that the element type
    *                  of this Array is a triple.
+   *  @param ct1    a class tag for T1 type parameter that is required to create an instance
+   *                of Array[T1]
+   *  @param ct2    a class tag for T2 type parameter that is required to create an instance
+   *                of Array[T2]
+   *  @param ct3    a class tag for T3 type parameter that is required to create an instance
+   *                of Array[T3]
    *  @return         a triple of Arrays, containing, respectively, the first, second, and third
    *                  elements from each element triple of this Array.
    */
-  def unzip3[T1: ClassTag, T2: ClassTag, T3: ClassTag](implicit asTriple: T => (T1, T2, T3)): (Array[T1], Array[T2], Array[T3]) = {
+  // implementation NOTE: ct1, ct2, ct3 can't be written as context bounds because desugared
+  // implicits are put in front of asPair parameter that is supposed to guide type inference
+  def unzip3[T1, T2, T3](implicit asTriple: T => (T1, T2, T3), ct1: ClassTag[T1], ct2: ClassTag[T2],
+    ct3: ClassTag[T3]): (Array[T1], Array[T2], Array[T3]) = {
     val a1 = new Array[T1](length)
     val a2 = new Array[T2](length)
     val a3 = new Array[T3](length)
diff --git a/test/files/neg/t8372.check b/test/files/neg/t8372.check
new file mode 100644
index 0000000000..6a6424a834
--- /dev/null
+++ b/test/files/neg/t8372.check
@@ -0,0 +1,7 @@
+t8372.scala:7: error: No ClassTag available for T1
+  def unzip[T1, T2](a: Array[(T1, T2)]) = a.unzip
+                                            ^
+t8372.scala:9: error: No ClassTag available for T1
+  def unzip3[T1, T2, T3](a: Array[(T1, T2, T3)]): (Array[T1], Array[T2], Array[T3]) = a.unzip3
+                                                                                        ^
+two errors found
diff --git a/test/files/neg/t8372.scala b/test/files/neg/t8372.scala
new file mode 100644
index 0000000000..60a674f4d8
--- /dev/null
+++ b/test/files/neg/t8372.scala
@@ -0,0 +1,10 @@
+class t8372 {
+  // failed with "error: tpe T1 is an unresolved spliceable type"; that was caused by
+  // misguided type inference of type parameters in ArrayOps.unzip
+  // the type inference failed because the order of implicit arguments was wrong
+  // the evidence that T <: (T1, T2) came as last argument so it couldn't guide the
+  // type inference early enough
+  def unzip[T1, T2](a: Array[(T1, T2)]) = a.unzip
+  // the same as above
+  def unzip3[T1, T2, T3](a: Array[(T1, T2, T3)]): (Array[T1], Array[T2], Array[T3]) = a.unzip3
+}