Rip out reporting indirection from CompilationUnit

Inline the forwarders from CompilationUnit, which should not affect behavior.
Since all forwarders lead to global.reporter, don't first navigate
to a compilation unit, only to then forward back to global.reporter.

The cleanup in the previous commits revealed a ton of confusion
regarding how to report an error.

This was a mechanical search/replace, which has low potential for messing
things up, since the list of available methods are disjoint between
`reporter` and `currentRun.reporting`. The changes involving `typer.context`
were done previously.

Essentially, there are three ways to report:
  - via typer.context, so that reporting can be silenced (buffered)
  - via global.currentRun.reporting, which summarizes (e.g., deprecation)
  - via global.reporter, which is (mostly) stateless and straightforward.

Ideally, these should all just go through `global.currentRun.reporting`,
with the typing context changing that reporter to buffer where necessary.

After the refactor, these are the ways in which we report (outside of typer):
  - reporter.comment
  - reporter.echo
  - reporter.error
  - reporter.warning
  - currentRun.reporting.deprecationWarning
  - currentRun.reporting.incompleteHandled
  - currentRun.reporting.incompleteInputError
  - currentRun.reporting.inlinerWarning
  - currentRun.reporting.uncheckedWarning

Before:
  - c.cunit.error
  - c.enclosingUnit.deprecationWarning
  - context.unit.error
  - context.unit.warning
  - csymCompUnit.warning
  - cunit.error
  - cunit.warning
  - currentClass.cunit.warning
  - currentIClazz.cunit.inlinerWarning
  - currentRun.currentUnit.error
  - currentRun.reporting
  - currentUnit.deprecationWarning
  - currentUnit.error
  - currentUnit.warning
  - getContext.unit.warning
  - getCurrentCUnit.error
  - global.currentUnit.uncheckedWarning
  - global.currentUnit.warning
  - global.reporter
  - icls.cunit.warning
  - item.cunit.warning
  - reporter.comment
  - reporter.echo
  - reporter.error
  - reporter.warning
  - reporting.deprecationWarning
  - reporting.incompleteHandled
  - reporting.incompleteInputError
  - reporting.inlinerWarning
  - reporting.uncheckedWarning
  - typer.context.unit.warning
  - unit.deprecationWarning
  - unit.echo
  - unit.error
  - unit.incompleteHandled
  - unit.incompleteInputError
  - unit.uncheckedWarning
  - unit.warning
  - v1.cunit.warning

All these methods ended up calling a method on `global.reporter`
or on `global.currentRun.reporting` (their interfaces are disjoint).

Also clean up `TypeDiagnostics`: inline nearly-single-use private methods.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/TailCalls.scala b/src/compiler/scala/tools/nsc/transform/TailCalls.scala
index d9d1192772..ef534f70fd 100644
--- a/src/compiler/scala/tools/nsc/transform/TailCalls.scala
+++ b/src/compiler/scala/tools/nsc/transform/TailCalls.scala
@@ -96,7 +96,7 @@ abstract class TailCalls extends Transform {
       val failReason  = failReasons(ctx)
       val failPos     = failPositions(ctx)
 
-      unit.error(failPos, s"could not optimize @tailrec annotated $method: $failReason")
+      reporter.error(failPos, s"could not optimize @tailrec annotated $method: $failReason")
     }
 
     /** Has the label been accessed? Then its symbol is in this set. */
@@ -268,14 +268,14 @@ abstract class TailCalls extends Transform {
       tree match {
         case ValDef(_, _, _, _) =>
           if (tree.symbol.isLazy && tree.symbol.hasAnnotation(TailrecClass))
-            unit.error(tree.pos, "lazy vals are not tailcall transformed")
+            reporter.error(tree.pos, "lazy vals are not tailcall transformed")
 
           super.transform(tree)
 
         case dd @ DefDef(_, name, _, vparamss0, _, rhs0) if isEligible(dd) =>
           val newCtx = new DefDefTailContext(dd)
           if (newCtx.isMandatory && !(newCtx containsRecursiveCall rhs0))
-            unit.error(tree.pos, "@tailrec annotated method contains no recursive calls")
+            reporter.error(tree.pos, "@tailrec annotated method contains no recursive calls")
 
           debuglog(s"Considering $name for tailcalls, with labels in tailpos: ${newCtx.tailLabels}")
           val newRHS = transform(rhs0, newCtx)