I removed `generatePropertiesFileSettings` from commonSettings
leaving projects that really need to use it to directly add it
to the settings. This was already being done (redundatly in some
cases) in `library`, `reflect`, `compiler`, `partestExtras`
and `partestJavaAgent`.

Before this PR (but after the SBT upgrade on 2.12.x branch):

```
➜  sbt 'show compiler/Compile/packageBin/mappings' | egrep 'repl-jline\.properties'
[info] * (/Users/jz/code/scala-2.12.x-reference/build/quick/classes/repl-jline/repl-jline.properties,repl-jline.properties)
[info] * (/Users/jz/code/scala-2.12.x-reference/build/quick/classes/repl-jline-embedded/repl-jline.properties,repl-jline.properties)

➜  sbt scala
[info] Loading global plugins from /Users/jz/.sbt/1.0/plugins
[info] Loading settings for project scala-2-12-x-reference-build-build from plugins.sbt ...
[info] Loading project definition from /Users/jz/code/scala-2.12.x-reference/project/project
[info] Loading settings for project scala-2-12-x-reference-build from plugins.sbt,build.sbt ...
[info] Loading project definition from /Users/jz/code/scala-2.12.x-reference/project
[info] Loading settings for project root from build.sbt ...
[info] Resolving key references (18230 settings) ...
[error] Could not determine commit date + SHA: org.eclipse.jgit.errors.MissingObjectException: Missing unknown b8c33ad
[info] *** Welcome to the sbt build definition for Scala! ***
[info] Check README.md for more information.
[error] java.util.zip.ZipException: duplicate entry: repl-jline.properties
```

After this PR:

```
fg: no current job
➜  sbt 'show compiler/Compile/packageBin/mappings' | egrep 'repl-jline\.properties'
[info] * (/Users/jz/code/scala-2.12.x-reference/build/quick/classes/repl-jline-embedded/repl-jline.properties,repl-jline.properties)

➜  sbt scala
[info] Loading global plugins from /Users/jz/.sbt/1.0/plugins
[info] Loading settings for project scala-2-12-x-reference-build-build from plugins.sbt ...
[info] Loading project definition from /Users/jz/code/scala-2.12.x-reference/project/project
[info] Loading settings for project scala-2-12-x-reference-build from plugins.sbt,build.sbt ...
[info] Loading project definition from /Users/jz/code/scala-2.12.x-reference/project
[info] Loading settings for project root from build.sbt ...
[info] Resolving key references (18194 settings) ...
[info] *** Welcome to the sbt build definition for Scala! ***
[info] Check README.md for more information.
[info] running (fork) scala.tools.nsc.MainGenericRunner -usejavacp
Welcome to Scala 2.12.11-20200203-035143-5bdfd31 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_221).
Type in expressions for evaluation. Or try :help.
```

Prior to the SBT upgrade, we also had the duplicate mapping:

```
sbt 'show compiler/compile:packageBin::mappings' | egrep 'repl-jline\.properties'
[info] * (/Users/jz/code/scala-2.12.x-reference/build/quick/classes/repl-jline/repl-jline.properties,repl-jline.properties)
[info] * (/Users/jz/code/scala-2.12.x-reference/build/quick/classes/repl-jline-embedded/repl-jline.properties,repl-jline.properties)
```

Avoid duplicate repl-jline.properties entries in compiler/packageBin

The List.intersect method creates a new list of elements,
which in this case was discarded (only the length matters).
Since typeParams is to be a list without repetitions, for
(A intersect B) to be the same length as B, it needs be that
all elements of B are contained in A.

create less objects for zipWithIndex

EmptySet and SetBuilder adjusted to take advantage of ++ optimisation for simple and common cases

eliminate unneeded allocations for HashSets where the result is already built for -
   subSet ++ superSet
   subSet union superSet
   superSet union subSet
   superSet ++ subSet

make a fast path when there is structural sharing in the HashSet
for union, guarantee internal operations will only return a new HashSet if one of the existing HashSet parameters or internal values cant be used

use System.arraycopy rather than Array.copy as it avoid JVM nulling the array

add missing `eq` fast path to intersect0 and diff0

minor improvements to + to reduce allocations

reduce calls to HashSet.size which can be a bottleneck

reduce allocations in ListSet ++, + and -
no allocations in ++ or + if the data is contained in the original sets

HashSetCollision1 stores its length so as to avoid calls to ListSet.size which is O(n)
take advantage of ListSet guarantees on identity for return or + or - where we can
avoid calling ListSet.size where we can avoid it

The keys in the resulting map are the same, so the internal structure
will also be the same, and that can be used to avoid allocating tuples
and going through `MapBuilder` and other such convolutions.

I thought som-snytt had recently gone on some sort of warning-cleanup
mission, but nowadays I can't compile 2.12.x without seeing scala tell
me off for these. Well, now I can.

Unlike .scala files, .java files are named and typed lazily: they will
only be analyzed when necessary to typecheck a Scala source. However,
under -Ypickle-java, pickler runs over them after typechecking, and can
force infos that otherwise wouldn't be forced. If typing the Java source
fails, the tree can contain erroneous types and symbols which will then
crash pickler as it attempts to write out the pickle.

This patch makes -Ypickle-java eagerly typecheck Java sources during
typer, so any errors will be emitted alongside Scala typer errors.

The enclosed test case previously crashed the compiler with a MatchError
on ErrorType.

Thoroughly typecheck Java sources for pickling

[nomerge] Update to sbt 1.3.8, remove workarounds

[nomerge] HashMap#transform reuses structure

fixes scala/scala-dev#666

fix our Windows Jenkins job (sbt 1.3 upgrade broke it)

…ores some imports

Co-authored-by: Dale Wijnand <dale.wijnand@gmail.com>

Always generate a `val INSTANCE` field, whether it's for class-based or
object-based, so that the access code branches needn't branch on
isClassBased.

This greatly simplifies the next commit, for handling value classes.

... by making any code snippet that defines (or seems to define) a value
class use the original "object-based" wrappers instead.

Co-authored-by: Dale Wijnand <dale.wijnand@gmail.com>

This avoids problems like

    private value read escapes its defining scope as part of type u.Type

when running `test/files/run/class-symbol-contravariant.scala` (and a
few others) with -Yrepl-class-based.

Also add a test specific for type aliases, extracted from
`test/files/jvm/interpreter.scala`, to run in class-based mode.

The Spark REPL uses -Yrepl-class-based and the change around
ImportHandler in interpreter/Imports (and that introduced the custom
wrapperCleanup phase for the REPL) requires -Yrepl-use-magic-imports be
set in order for the Spark REPL to continue to work correctly.  Rather
than affect all existing Spark releases that choose to upgrade Scala, we
preserve the functioning of the Spark REPL by enabling "magic imports"
when using the class-based wrappers.

... and thus -Yrepl-use-magic-imports too.

The intent is for these to be true, but we'll do that for 2.13.x,
not 2.12.x.

Warn use of a deprecated class' static method

The custom phase that does this needs to descend deeper than
the first `Template`.

It now works bottom up (from the innermost `$iw`) and runs the
unused analysis at each level, feeding the possibly simpilfied
trees into the analysis of the enclosing level.

I also needed to add a special case for the `lineXY$read`
variable names which should be considered private for the
purpose of this analysis.

This reverts commit c5f1424.

This should help ensure the order is as deterministic as possible.

[2.12] Improve -Yrepl-class-based

Avoid IntRef and other overheads in `ScalaRuntime.{toArray, toObjectArray}`

[nomerge] optimise the addition of immutable HashMap

dont create a TreeMap if the underlying tree is unchanged

Dont create a new TreeSet if there is no change to the underlying tree

Basic TreeSet/TreeMap benchmark

A simple TreeSetBuilder

…sable

remove some refs in TraversableOnce