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Fix #3703: Various fixes to make printing more robust in face of errors #3705

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Merged
merged 4 commits into from
Jan 27, 2018
Merged

Fix #3703: Various fixes to make printing more robust in face of errors #3705

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6fe165f
Fix #3703: Various fixes to make printing more robust in face of errors
odersky Dec 28, 2017
bd14d11
Add neg test to show it no longer crashes
odersky Dec 28, 2017
9b48d07
More test to pos
odersky Jan 14, 2018
03c6526
Fix typo in test
odersky Jan 15, 2018
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6 changes: 5 additions & 1 deletion compiler/src/dotty/tools/dotc/ast/Trees.scala
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Expand Up @@ -113,7 +113,11 @@ object Trees {
*/
def withType(tpe: Type)(implicit ctx: Context): ThisTree[Type] = {
if (tpe.isInstanceOf[ErrorType])
assert(!Config.checkUnreportedErrors || ctx.reporter.errorsReported)
assert(!Config.checkUnreportedErrors ||
ctx.reporter.errorsReported ||
ctx.settings.YshowPrintErrors.value
// under -Yshow-print-errors, errors might arise during printing, but they do not count as reported
)
else if (Config.checkTreesConsistent)
checkChildrenTyped(productIterator)
withTypeUnchecked(tpe)
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/printing/Formatting.scala
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Expand Up @@ -34,7 +34,7 @@ object Formatting {
case NonFatal(ex)
if !ctx.mode.is(Mode.PrintShowExceptions) &&
!ctx.settings.YshowPrintErrors.value =>
s"[cannot display due to $ex, raw string = $toString]"
s"[cannot display due to $ex, raw string = ${arg.toString}]"
}
case _ => arg.toString
}
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12 changes: 10 additions & 2 deletions compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
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Expand Up @@ -196,7 +196,12 @@ class PlainPrinter(_ctx: Context) extends Printer {
else toText(tp.origin)
}
case tp: LazyRef =>
"LazyRef(" ~ toTextGlobal(tp.ref) ~ ")" // TODO: only print this during debug mode?
def refTxt =
try toTextGlobal(tp.ref)
catch {
case ex: Throwable => Str("...")
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Is this just to catch infinite loops in LazyRefs? If so I'd just catch StackOverflowException, though I think it'd be cleaner to do loop detection in LazyRef#ref.

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Yes, it's to detect stack overflows. Evaluation of LazyRefs is not tail-recursive, so we will always get a stack overflow. Maybe we can do a better job in loop detection but I believe the two issues are separate.

}
"LazyRef(" ~ refTxt ~ ")"
case _ =>
tp.fallbackToText(this)
}
Expand All @@ -217,7 +222,10 @@ class PlainPrinter(_ctx: Context) extends Printer {

/** If -uniqid is set, the hashcode of the lambda type, after a # */
protected def lambdaHash(pt: LambdaType): Text =
if (ctx.settings.uniqid.value) "#" + pt.hashCode else ""
if (ctx.settings.uniqid.value)
try "#" + pt.hashCode
catch { case ex: NullPointerException => "" }
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Couldn't we do a null check first instead of catching NullPointerException ? This is fishy in general and is also not something that can be done on Scala.js by default (https://www.scala-js.org/doc/semantics.html)

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No, hashCode is computed, the null could be in a referenced type.

else ""

/** If -uniqid is set, the unique id of symbol, after a # */
protected def idString(sym: Symbol): String =
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala
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Expand Up @@ -501,7 +501,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
typeDefText(tparamsTxt, toText(rhs))
case LambdaTypeTree(tparams, body) =>
recur(body, tparamsText(tparams))
case rhs: TypeTree if rhs.tpe.isInstanceOf[TypeBounds] =>
case rhs: TypeTree if rhs.typeOpt.isInstanceOf[TypeBounds] =>
typeDefText(tparamsTxt, toText(rhs))
case rhs =>
typeDefText(tparamsTxt, optText(rhs)(" = " ~ _))
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11 changes: 11 additions & 0 deletions tests/pos/i3703.scala
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@@ -0,0 +1,11 @@
package bar {
trait M[F[_]]
class S[XS[_] <: M[XS], A](val x: XS[A])
object S {
def apply[X[_] <: M[X], A](x: X[A]): S[X, A] = S[X, A](x)
def unapply[X[_] <: M[X], A](p: S[X, A]): S[X, A] = S(p.x)
}
}