Added -Xdev setting... you know, for devs

A setting we developers can give all the time and expect to
hear useful things without being buried in debugging output.
As the comment says:

  This is for WARNINGS which should reach the ears of scala
  developers whenever they occur, but are not useful for normal
  users. They should be precise, explanatory, and infrequent. Please
  don't use this as a logging mechanism. !!! is prefixed to all
  messages issued via this route to make them visually distinct.

This is what I always intended for "debugwarn", the method
I have deprecated in favor of the more accurate:

  def devWarning(msg: => String): Unit

In this VERY SAME COMMIT, I performed the CLOSELY RELATED
task of quieting down an -Xlint warning which had become too
noisy thanks to implicit classes tickling it. I tightened that
warn condition to include both -Xlint and -Xdev.

8 files changed, 15 insertions, 9 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Checkable.scala b/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
index 166a9785fa..9efa3f36b0 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
@@ -130,7 +130,7 @@ trait Checkable {
       else if (P3) RuntimeCheckable
       else if (uncheckableType == NoType) {
         // Avoid warning (except ourselves) if we can't pinpoint the uncheckable type
-        debugwarn("Checkability checker says 'Uncheckable', but uncheckable type cannot be found:\n" + summaryString)
+        debuglog("Checkability checker says 'Uncheckable', but uncheckable type cannot be found:\n" + summaryString)
         CheckabilityError
       }
       else Uncheckable
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 78380ad054..0a9baca58b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -398,8 +398,10 @@ trait Contexts { self: Analyzer =>
       unit.error(pos, if (checking) "\n**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg)
 
     @inline private def issueCommon(err: AbsTypeError)(pf: PartialFunction[AbsTypeError, Unit]) {
-      debugwarn("issue error: " + err.errMsg)
-      if (settings.Yissuedebug.value) (new Exception).printStackTrace()
+      if (settings.Yissuedebug.value) {
+        log("issue error: " + err.errMsg)
+        (new Exception).printStackTrace()
+      }
       if (pf isDefinedAt err) pf(err)
       else if (bufferErrors) { buffer += err }
       else throw new TypeError(err.errPos, err.errMsg)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 576a21fe31..710b7e9051 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -82,7 +82,7 @@ trait Implicits {
     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))
-      debugwarn("update buffer: " + implicitSearchContext.errBuffer)
+      debuglog("update buffer: " + implicitSearchContext.errBuffer)
     }
     printInference("[infer implicit] inferred " + result)
     context.undetparams = context.undetparams filterNot result.subst.from.contains
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 6e42481d60..ac367dfde6 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1319,7 +1319,8 @@ trait Infer extends Checkable {
           new TreeTypeSubstituter(undetparams, targs).traverse(tree)
           notifyUndetparamsInferred(undetparams, targs)
         case _ =>
-          debugwarn("failed inferConstructorInstance for "+ tree  +" : "+ tree.tpe +" under "+ undetparams +" pt = "+ pt +(if(isFullyDefined(pt)) " (fully defined)" else " (not fully defined)"))
+          def full = if (isFullyDefined(pt)) "(fully defined)" else "(not fully defined)"
+          devWarning(s"failed inferConstructorInstance for $tree: ${tree.tpe} undet=$undetparams, pt=$pt $full")
           // if (settings.explaintypes.value) explainTypes(resTp.instantiateTypeParams(undetparams, tvars), pt)
           ConstrInstantiationError(tree, resTp, pt)
       }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 04fb69671e..ee1b1f9b37 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -336,7 +336,7 @@ trait Namers extends MethodSynthesis {
 
     private def enterClassSymbol(tree: ClassDef, clazz: ClassSymbol): Symbol = {
       if (clazz.sourceFile != null && clazz.sourceFile != contextFile)
-        debugwarn("!!! Source mismatch in " + clazz + ": " + clazz.sourceFile + " vs. " + contextFile)
+        devWarning(s"Source file mismatch in $clazz: ${clazz.sourceFile} vs. $contextFile")
 
       clazz.associatedFile = contextFile
       if (clazz.sourceFile != null) {
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
index 7cb420d2dc..6c916649f0 100644
--- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
@@ -271,7 +271,9 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
       // we don't transform after uncurry
       // (that would require more sophistication when generating trees,
       //  and the only place that emits Matches after typers is for exception handling anyway)
-      if(phase.id >= currentRun.uncurryPhase.id) debugwarn("running translateMatch at "+ phase +" on "+ selector +" match "+ cases)
+      if (phase.id >= currentRun.uncurryPhase.id)
+        devWarning(s"running translateMatch past uncurry (at $phase) on $selector match $cases")
+
       patmatDebug("translating "+ cases.mkString("{", "\n", "}"))
 
       val start = if (Statistics.canEnable) Statistics.startTimer(patmatNanos) else null
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 9eb06dbdbf..7a7c7c7d25 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -139,7 +139,8 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
         }
       }
 
-      if (settings.lint.value) {
+      // This has become noisy with implicit classes.
+      if (settings.lint.value && settings.developer.value) {
         clazz.info.decls filter (x => x.isImplicit && x.typeParams.nonEmpty) foreach { sym =>
           val alts = clazz.info.decl(sym.name).alternatives
           if (alts.size > 1)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index d9084af7bc..fb5c5e6f84 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1545,7 +1545,7 @@ trait Typers extends Modes with Adaptations with Tags {
 
             val preSuperVals = treeInfo.preSuperFields(templ.body)
             if (preSuperVals.isEmpty && preSuperStats.nonEmpty)
-              debugwarn("Wanted to zip empty presuper val list with " + preSuperStats)
+              devWarning("Wanted to zip empty presuper val list with " + preSuperStats)
             else
               map2(preSuperStats, preSuperVals)((ldef, gdef) => gdef.tpt.tpe = ldef.symbol.tpe)