[backport] Fix unsafe array opt. / opt. primitive Array(...)

SI-6611, SI-6247 (partial fix)

The original commits on master were a bit circuitous, this
is squashed to a neat little package.

I had to add type arguments to the Array.apply calls in the
test case, they are inferred on master.

commit 41ff05dfdbcf032157b3509ace633f2e7a12295c
Author: Jason Zaugg <jzaugg@gmail.com>
Date:   Sun Nov 4 14:44:59 2012 +0100

    Refactor guards checking for a particular overload of Array.apply.
    (cherry picked from commit 092345a24c22a821204fb358d33272ae8f7353be)

commit 1e5c942deccaf64f8d57bd8891b912381d7f220a
Author: Jason Zaugg <jzaugg@gmail.com>
Date:   Sun Nov 4 14:17:25 2012 +0100

    Expand optimization of Array(e1, ..., en) to primitive arrays.
    (cherry picked from commit 8265175ecc42293997d59049f430396c77a2b891)

commit ab1bf77e39f2dfeacf3fc107ccb2907a1867f04c
Author: Jason Zaugg <jzaugg@gmail.com>
Date:   Sat Nov 3 13:34:20 2012 +0100

    SI-6611 Tighten up an unsafe array optimization

    The net was cast too wide and was unsafely optimizing away array
    copies.
    (cherry picked from commit dad886659faca4fba2d4937c9bc6780591b02c27)

And also:

Optimize primitive Array(e1, ..., en)

Expands an existing optimization for reference arrays to
apply to primitives, as well.

Fixes one aspect of SI-6247.
(cherry picked from commit cac5a08611f9511ba4d94b99db630404efae190a)

Conflicts:
	src/compiler/scala/tools/nsc/transform/CleanUp.scala

More principled tree copying.

Canonical > home-spun.

Conflicts:
	src/compiler/scala/tools/nsc/transform/CleanUp.scala

1 files changed, 10 insertions, 0 deletions

diff --git a/src/library/scala/Array.scala b/src/library/scala/Array.scala
index 90684b5fdd..b9f51803ec 100644
--- a/src/library/scala/Array.scala
+++ b/src/library/scala/Array.scala
@@ -115,6 +115,8 @@ object Array extends FallbackArrayBuilding {
    *  @param xs the elements to put in the array
    *  @return an array containing all elements from xs.
    */
+  // Subject to a compiler optimization in Cleanup.
+  // Array(e0, ..., en) is translated to { val a = new Array(3); a(i) = ei; a }
   def apply[T: ClassTag](xs: T*): Array[T] = {
     val array = new Array[T](xs.length)
     var i = 0
@@ -123,6 +125,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Boolean` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Boolean, xs: Boolean*): Array[Boolean] = {
     val array = new Array[Boolean](xs.length + 1)
     array(0) = x
@@ -132,6 +135,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Byte` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Byte, xs: Byte*): Array[Byte] = {
     val array = new Array[Byte](xs.length + 1)
     array(0) = x
@@ -141,6 +145,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Short` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Short, xs: Short*): Array[Short] = {
     val array = new Array[Short](xs.length + 1)
     array(0) = x
@@ -150,6 +155,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Char` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Char, xs: Char*): Array[Char] = {
     val array = new Array[Char](xs.length + 1)
     array(0) = x
@@ -159,6 +165,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Int` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Int, xs: Int*): Array[Int] = {
     val array = new Array[Int](xs.length + 1)
     array(0) = x
@@ -168,6 +175,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Long` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Long, xs: Long*): Array[Long] = {
     val array = new Array[Long](xs.length + 1)
     array(0) = x
@@ -177,6 +185,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Float` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Float, xs: Float*): Array[Float] = {
     val array = new Array[Float](xs.length + 1)
     array(0) = x
@@ -186,6 +195,7 @@ object Array extends FallbackArrayBuilding {
   }
 
   /** Creates an array of `Double` objects */
+  // Subject to a compiler optimization in Cleanup, see above.
   def apply(x: Double, xs: Double*): Array[Double] = {
     val array = new Array[Double](xs.length + 1)
     array(0) = x