hooks for naming and synthesis in Namers.scala and Typers.scala

Interestingly enough, despite of the implementation surface being
quite noticeable, it is enough to hijack just `enterSym` and typechecking
of stats for packages, templates and blocks in order to enable macro annotations.
That and `ensureCompanionObject`, which I couldn't abstract away so far.

An architectural note: given that a hooked method is called `X`,
there are two implementations of this method. `pluginsX` is defined in
AnalyzerPlugins.scala and lets macro plugins customize `X`.
`standardX` is defined next to `X` and provides a default implementation.
Finally `X` is changed to trivially forward to `pluginsX`.

Existing and future callers of `X` now can be completely oblivious of the
introduced hooks, because calls to `X` will continue working and will be
correctly hooked. This makes the infrastructure more robust.

The only downside is that in case when a macro plugin wants to call
into the default implementation, it needs to call `standardX`, because
`X` will lead to a stack overflow. However, in my opinion this not a big
problem, because such failures are load and clear + for every `pluginsX`
we actually provide documentation that says what is its standard impl is.

1 files changed, 2 insertions, 2 deletions

diff --git a/test/files/run/macroPlugins-namerHooks.scala b/test/files/run/macroPlugins-namerHooks.scala
index b0f29cbbed..a71d685f7f 100644
--- a/test/files/run/macroPlugins-namerHooks.scala
+++ b/test/files/run/macroPlugins-namerHooks.scala
@@ -18,12 +18,12 @@ object Test extends DirectTest {
     object macroPlugin extends MacroPlugin {
       override def pluginsEnterSym(namer: Namer, tree: Tree): Boolean = {
         output += s"enterSym(${tree.toString.replace('\n', ' ')})"
-        namer.enterSym(tree)
+        namer.standardEnterSym(tree)
         true
       }
       override def pluginsEnsureCompanionObject(namer: Namer, cdef: ClassDef, creator: ClassDef => Tree = companionModuleDef(_)): Option[Symbol] = {
         output += s"ensureCompanionObject(${cdef.toString.replace('\n', ' ')}, ...)"
-        Some(namer.ensureCompanionObject(cdef, creator))
+        Some(namer.standardEnsureCompanionObject(cdef, creator))
       }
       override def pluginsEnterStats(typer: Typer, stats: List[Tree]): List[Tree] = {
         stats.foreach(stat => output += s"enterStat(${stat.toString.replace('\n', ' ')})")