Harden a condition in Types

odersky · odersky · commit 30e1aef5bdc1 · 2019-12-03T17:06:50.000+01:00
diff --git a/compiler/src/dotty/tools/dotc/core/Types.scala b/compiler/src/dotty/tools/dotc/core/Types.scala
@@ -2006,7 +2006,7 @@ object Types {
 
       val idx = typeParams.indexOf(param)
 
-      if (idx < args.length) {
+      if (0 <= idx && idx < args.length) {
         val argInfo = args(idx) match {
           case arg: TypeBounds =>
             val v = param.paramVariance
diff --git a/compiler/src/dotty/tools/dotc/reporting/Reporter.scala b/compiler/src/dotty/tools/dotc/reporting/Reporter.scala
@@ -133,8 +133,7 @@ trait Reporting { this: Context =>
   def error(msg: => Message, pos: SourcePosition = NoSourcePosition, sticky: Boolean = false): Unit = {
     val fullPos = addInlineds(pos)
     reporter.report(if (sticky) new StickyError(msg, fullPos) else new Error(msg, fullPos))
-    if (ctx.settings.YdebugError.value)
-      Thread.dumpStack()
+    if ctx.settings.YdebugError.value then Thread.dumpStack()
   }
 
   def error(ex: TypeError, pos: SourcePosition): Unit = {

Original file line number	Diff line number	Diff line change
`@@ -133,8 +133,7 @@ trait Reporting { this: Context =>`
`133`	`133`	`def error(msg: => Message, pos: SourcePosition = NoSourcePosition, sticky: Boolean = false): Unit = {`
`134`	`134`	`val fullPos = addInlineds(pos)`
`135`	`135`	`reporter.report(if (sticky) new StickyError(msg, fullPos) else new Error(msg, fullPos))`
`136`		`- if (ctx.settings.YdebugError.value)`
`137`		`- Thread.dumpStack()`
	`136`	`+ if ctx.settings.YdebugError.value then Thread.dumpStack()`
`138`	`137`	`}`
`139`	`138`
`140`	`139`	`def error(ex: TypeError, pos: SourcePosition): Unit = {`