SI-7345 Prefer using a throwaway silent context over buffer flushing.

When we are using a throwaway silent context, we can just let it drift out of
scope and over the horizon, rather than ceremoniously flushing its buffers
on completion.

 - Applied to Scaladoc.
 - Applied to Infer#isApplicableSafe. Less manual error buffer management
   affords greater opportunity to cleanly express the logic.
 - Applied to `typerReportAnyContextErrors`.

The reasoning for the last case is as follows:

 - There were only two callers to `typerReportAnyContextErrors`, and
   they both passed in as `c` a child context of `context`.
 - That child context must share the error reporting mode and buffer
   with `context`.
 - Therefore, extracting an error from `c` and issuing it into `context`
   is a no-op. Because the error buffer is Set, it was harmless.

This part will probably textually conflict with the same change made in
SI-7319, but the end results are identical.

1 files changed, 3 insertions, 6 deletions

diff --git a/src/scaladoc/scala/tools/nsc/doc/model/ModelFactoryImplicitSupport.scala b/src/scaladoc/scala/tools/nsc/doc/model/ModelFactoryImplicitSupport.scala
index 65b00d4673..6cefe34887 100644
--- a/src/scaladoc/scala/tools/nsc/doc/model/ModelFactoryImplicitSupport.scala
+++ b/src/scaladoc/scala/tools/nsc/doc/model/ModelFactoryImplicitSupport.scala
@@ -226,12 +226,9 @@ trait ModelFactoryImplicitSupport {
       // look for type variables in the type. If there are none, we can decide if the implicit is there or not
       if (implType.isTrivial) {
         try {
-          context.flushBuffer() /* any errors here should not prevent future findings */
-          // TODO: Not sure this is the right thing to do -- seems similar to what scalac should be doing
-          val context2 = context.make(owner = sym.owner)
-          val search = inferImplicit(EmptyTree, tpe, false, false, context2, false)
-          context.flushBuffer() /* any errors here should not prevent future findings */
-
+          // TODO: Not sure if `owner = sym.owner` is the right thing to do -- seems similar to what scalac should be doing
+          val silentContext = context.make(owner = sym.owner).makeSilent(reportAmbiguousErrors = false)
+          val search = inferImplicit(EmptyTree, tpe, false, false, silentContext, false)
           available = Some(search.tree != EmptyTree)
         } catch {
           case _: TypeError =>