SI-7345 Encapsulate warning and error buffers in ReportBuffer.

  - merge `Context#{buffer, warningBuffer}` into `Context#reportBuffer`.
  - only expose immutable copies of the error and warnings buffers
  - Introduce a convenience method, `firstError`.
  - replace `condBufferFlush` more specific methods to retain or
    clear errors by error kind.

1 files changed, 13 insertions, 9 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 85e31347be..f7f6970c14 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -81,8 +81,8 @@ trait Implicits {
     val implicitSearchContext = context.makeImplicit(reportAmbiguous)
     val result = new ImplicitSearch(tree, pt, isView, implicitSearchContext, pos).bestImplicit
     if (saveAmbiguousDivergent && implicitSearchContext.hasErrors) {
-      context.updateBuffer(implicitSearchContext.errBuffer.filter(err => err.kind == ErrorKinds.Ambiguous || err.kind == ErrorKinds.Divergent))
-      debuglog("update buffer: " + implicitSearchContext.errBuffer)
+      context.updateBuffer(implicitSearchContext.reportBuffer.errors.filter(err => err.kind == ErrorKinds.Ambiguous || err.kind == ErrorKinds.Divergent))
+      debuglog("update buffer: " + implicitSearchContext.reportBuffer.errors)
     }
     printInference("[infer implicit] inferred " + result)
     context.undetparams = context.undetparams filterNot result.subst.from.contains
@@ -585,8 +585,9 @@ trait Implicits {
           case _ => fallback
         }
         if (context.hasErrors) {
-          log("implicit adapt failed: " + context.errBuffer.head.errMsg)
-          return fail(context.errBuffer.head.errMsg)
+          val err = context.firstError
+          log("implicit adapt failed: " + err.errMsg)
+          return fail(err.errMsg)
         }
 
         if (Statistics.canEnable) Statistics.incCounter(typedImplicits)
@@ -609,7 +610,7 @@ trait Implicits {
         }
 
         if (context.hasErrors)
-          fail("hasMatchingSymbol reported error: " + context.errBuffer.head.errMsg)
+          fail("hasMatchingSymbol reported error: " + context.firstError.errMsg)
         else if (isLocal && !hasMatchingSymbol(itree1))
           fail("candidate implicit %s is shadowed by %s".format(
             info.sym.fullLocationString, itree1.symbol.fullLocationString))
@@ -633,7 +634,7 @@ trait Implicits {
             // #2421: check that we correctly instantiated type parameters outside of the implicit tree:
             checkBounds(itree2, NoPrefix, NoSymbol, undetParams, targs, "inferred ")
             if (context.hasErrors)
-              return fail("type parameters weren't correctly instantiated outside of the implicit tree: " + context.errBuffer.head.errMsg)
+              return fail("type parameters weren't correctly instantiated outside of the implicit tree: " + context.firstError.errMsg)
 
             // filter out failures from type inference, don't want to remove them from undetParams!
             // we must be conservative in leaving type params in undetparams
@@ -669,7 +670,7 @@ trait Implicits {
             }
 
             if (context.hasErrors)
-              fail("typing TypeApply reported errors for the implicit tree: " + context.errBuffer.head.errMsg)
+              fail("typing TypeApply reported errors for the implicit tree: " + context.firstError.errMsg)
             else {
               val result = new SearchResult(itree2, subst)
               if (Statistics.canEnable) Statistics.incCounter(foundImplicits)
@@ -828,7 +829,7 @@ trait Implicits {
             case sr if sr.isFailure =>
               // We don't want errors that occur during checking implicit info
               // to influence the check of further infos.
-              context.condBufferFlush(_.kind != ErrorKinds.Divergent)
+              context.reportBuffer.retainErrors(ErrorKinds.Divergent)
               rankImplicits(is, acc)
             case newBest        =>
               best = newBest
@@ -1085,7 +1086,10 @@ trait Implicits {
 
         try {
           val tree1 = typedPos(pos.focus)(arg)
-          if (context.hasErrors) processMacroExpansionError(context.errBuffer.head.errPos, context.errBuffer.head.errMsg)
+          if (context.hasErrors) {
+            val err = context.firstError
+            processMacroExpansionError(err.errPos, err.errMsg)
+          }
           else new SearchResult(tree1, EmptyTreeTypeSubstituter)
         } catch {
           case ex: TypeError =>