SI-6370 changed ListMap apply0 method to produce correct error message when a key is not found
Current implementation of apply0 relies on tail method to iterate over all keys.
When the list gets to its end, tail produces an 'empty map' message in its exception, which is thrown by ListMap.
This change checks if the collection is empty before calling tail and provides a more appropriate key not found message.

Signed-off-by: Vinicius Miana <vinicius@miana.com.br>
SI-6935 Added readResolve in BoxedUnit
When deserializing Unit, it would return an instance of Object, but not a Scala Unit.
By adding readResolve, the deserialization of Unit will work.
SI-6225 Fix import of inherited package object implicits

The prefix in the ImplicitInfo must be com.acme.`package`.type,
rather than com.acme.
SI-6158 Restore compile error output under partest --show-log

Seems like the ifs and elses didn't quite survive e830a7ce9.

Before:

    ./test/partest --show-log test/files/run/foo.scala
    Testing individual files
    testing: [...]/files/run/foo.scala                                    [FAILED]

Now:

    ./test/partest --show-log test/files/run/foo.scala
    Testing individual files
    testing: [...]/files/run/foo.scala                                    [FAILED]
    foo.scala:1: error: expected class or object definition
    askdfjskl
    ^
    one error found
    1 of 1 tests failed (elapsed time: 00:00:01)
Tolerate symbol sharing between accessor/field.

Recently, TreeCheckers (-Ycheck) was extended to
report on references to symbols that were not in
scope, which is often a sign that some substitution
or ownership changes have been omitted.

But, accessor methods directly use the type of the
underlying field, without cloning symbols defined
in that type, such as quantified types in existentials,
at the new owner.

My attempt to change this broke pos/existentials.scala.

Instead, I'll just look the other way in TreeCheckers.
SI-7091 Add a diagnostic for the "no acc def buf" error.
SI-6514 Avoid spurious dead code warnings

`deadCode.expr` stores the method symbol most recently encountered
in `handleMonomorphicCall`, and uses this to avoid warnings
for arguments to label jumps and `Object#synchronized` (which
sneakily acts by-name without advertising the fact in its type.)

But this scheme was insufficient if the argument itself contains
another method call, such as `matchEnd(throw e(""))`.

This commit changes the single slot to a stack, and also
grants exemption to `LabelDef` trees. They were incorrectly
flagged in the enclosed test case after I made the the first change.
Merge pull request #2099 from retronym/ticket/6158

SI-6158 Restore compile error output under partest --show-log
silences t6323a

Tag materialization notices enabled with -Xlog-implicits are now echoes
not printlns. Therefore, they go into stderr, not stdout, getting logged
by partest and not spamming stdout of partest.
moves Symbol#SymbolKind to Symbols

Too bad I didn't notice that before. That will free up quite a bit of
memory, removing an extraneous field in every single Symbol, namely the:

private volatile Symbols.Symbol.SymbolKind$ SymbolKind$module
removes the crazy extraneous log
synchronizes symbols

Synchronization via decoration would be neat if it actually worked.
Unfortunately, root symbols never got decorated, therefore their children
also never got decorated and all the way down to the very turtles.

This commit fixes this sad issue by turning root symbols from objects
to lazy vals. Yes, this is going to induce a performance penalty, which
will hopefully not be high enough to invalidate this cornerstone of our
synchronization strategy.

Now when root symbols are lazy vals, they can be overridden in the runtime
reflexive universe and decorated with SynchronizedSymbol, which makes their
children sync and sound.
reflection no longer uses atPhase and friends

Mentioned methods mutate the global `atPhaseStack` variable, which can
easily lead to imbalances and, ultimately, to the empty stack error.

Luckily for us, there's only one dummy phase, SomePhase, which is used
by runtime reflection, so there is absolutely zero need to invoke atPhase
in non-compiler reflexive universes.

The cleanest solution would be to override `atPhase` for runtime reflection,
but it's @inline final, so I didn't want to pay performance penalties for
something that's used three times in runtime reflection (during unpickling, in
reflection-specific completers and in `Symbol.typeParams/unsafeTypeParams`).

Therefore I added overrideable analogues of `atPhase` and `atPhaseNotLaterThan`
which are called from the aforementioned code shared between the compiler and
runtime reflection. I also had to duplicate the code of `Symbol.XXXtypeParams`,
again due to them being very performance-sensitive.
cleans up initialization of runtime reflection

At first I just tried to remove syntheticCoreClasses from missingHook
and put them into the initializer of freshly created mirrors in order to
reduce the non-determinism in mutations of the global symbol table.

And then it didn't work, crashing on me claiming that AnyRef is missing.
Apparently we still need AnyRefClass in missingHook, just because it's
impossible to initialize (i.e. unpickle) ScalaPackageClass without it.

And then it still didn't work, whining about multiple overloaded defs
of some synthetic symbols. That was really tricky, but I figured it out
as well by initializing ScalaPackageClass first before forcing any
synthetic symbols (see the details in comments).
introduces GIL to Scala reflection

On a serious note, I feel really uncomfortable about having to juggle
this slew of locks. Despite that I can't immediately find a deadlock,
I'm 100% sure there is one hiding in the shadows. Hence, I'm abandoning
all runtime reflection locks in favor of a single per-universe one.
initializes lazy vals and inner objects in advance

As discussed at http://groups.google.com/group/scala-internals/browse_thread/thread/97840ba4fd37b52e,
`synchronized(this)` employed by lazy val and inner object initialization
is an excellent way to deadlock yourself in the foot.

Imagine a thread, which grabs a reflection GIL and then calls one of those
lazy vals / objects that reflection exposes (e.g. a companion module of
an innocently looking SingleType case class). Then imagine another thread,
which calls something else in SymbolTable, grabbing symbol table's monitor,
and then tries to get a reflection GIL to do something non-trivial. Hello,
we've just arrived at a deadlock.

Since, as discussed in the aforementioned thread, there's no easy way to
change lazy vals / inner objects in reflection to use GIL instead of
synchronizing on this, I bit the bullet and manually initialized all
things with deferred initialization defined in reflect.runtime.SymbolTable.

The list of all things `$lzycompute` has been mined by a simple Python script,
then I copy/pasted that list into `JavaUniverse.scala` and went ahead forcing
objects and lazy vals mentioned there. Notably, I've been able to force all
lazy vals in Definitions.scala.

There are some todos left, but I suggest we move forward without securing them,
because the 2.10.1-RC1 release date is very close, so we'd better have a 95%
solution instead of keeping reflection thread-unsafe. Though here's the list of
todo lazy vals for the reference:

  * BaseTypeSeq.maxDepth
  * WeakTypeTag.tpe
  * AnnotationInfo.forcedInfo

For each of those lazy vals we need to make sure that their initializers never
call back into themselves. Otherwise, there's a danger of a deadlock.
optimizes Scala reflection GIL

First of all, GIL should only apply to runtime reflection, because noone
is going to run toolboxes in multiple threads: a) that's impossible, b/c
the compiler isn't thread safe, b) ToolBox api prevents that.

Secondly, the only things in symbols which require synchronization are:
1) info/validTo (completers aren't thread-safe),
2) rawInfo and its dependencies (it shares a mutable field with info)
3) non-trivial caches like in typeAsMemberOfLock

If you think about it, other things like sourceModule or associatedFile
don't need synchronization, because they are either set up when a symbol
is created or cloned or when it's completed. The former is obviously safe,
while the latter is safe as well, because before acquiring init-dependent
state of symbols, the compiler calls `initialize`, which is synchronized.

We can say that symbols can be in four possible states: 1) being created,
2) created, but not yet initialized, 3) initializing, 4) initialized.
in runtime reflection can undergo is init. #3 is dangerous and needs protection
SI-7045 reflection now auto-initializes selfType

selfType joins the happy family of flags, annotations and privateWithin,
which automatically trigger initialization, when used within runtime
reflection.
synchronizes toolboxes

We don't guarantee thread-safety of the front end, but everything else
looks good now.
synchronizes pendingVolatiles

Called from isVolatile, which is called from isStable, which is a part
of the public reflection API.