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author | Paul Phillips <paulp@improving.org> | 2013-04-22 07:59:26 -0700 |
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committer | Paul Phillips <paulp@improving.org> | 2013-04-22 09:26:08 -0700 |
commit | 7b4e450e9b746a9289f6d429cdee73bffa5cd733 (patch) | |
tree | c34f3dbe89eac6b3328eead8baf866d16b50c336 | |
parent | 1d54f26b9a87c8df6a3b0e4472147d1ffb9037f1 (diff) | |
download | scala-7b4e450e9b746a9289f6d429cdee73bffa5cd733.tar.gz scala-7b4e450e9b746a9289f6d429cdee73bffa5cd733.tar.bz2 scala-7b4e450e9b746a9289f6d429cdee73bffa5cd733.zip |
SI-4365 nondeterministic failure in asSeenFrom
Under some order-dependent conditions (if source files arrive
in one order it happens, in the other order it does not) more
than one set of type parameters are created for a given class.
Previously this would lead to a crash in asSeenFrom when a type
parameter had to be matched up with a type application.
Now when that situation arises I compare them by name and log
a dev warning if it hits. This does not risk anything undesirable
happening because the wayward type parameter's owner is always
the right class; it's only the class type parameters which don't
include the wayward one. Since in a given type parameter list
names are unique, we have enough information to salvage the
search.
-rw-r--r-- | src/reflect/scala/reflect/internal/tpe/TypeMaps.scala | 40 | ||||
-rw-r--r-- | test/files/pos/t4365/a_1.scala | 18 | ||||
-rw-r--r-- | test/files/pos/t4365/b_1.scala | 22 |
3 files changed, 72 insertions, 8 deletions
diff --git a/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala b/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala index 0f9db31ec1..4227699da2 100644 --- a/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala +++ b/src/reflect/scala/reflect/internal/tpe/TypeMaps.scala @@ -525,15 +525,39 @@ private[internal] trait TypeMaps { val TypeRef(_, rhsSym, rhsArgs) = rhs require(lhsSym.safeOwner == rhsSym, s"$lhsSym is not a type parameter of $rhsSym") - // Find the type parameter position; we'll use the corresponding argument - val argIndex = rhsSym.typeParams indexOf lhsSym - - if (argIndex >= 0 && argIndex < rhsArgs.length) // @M! don't just replace the whole thing, might be followed by type application - appliedType(rhsArgs(argIndex), lhsArgs mapConserve this) - else if (rhsSym.tpe_*.parents exists typeIsErroneous) // don't be too zealous with the exceptions, see #2641 + // Find the type parameter position; we'll use the corresponding argument. + // Why are we checking by name rather than by equality? Because for + // reasons which aren't yet fully clear, we can arrive here holding a type + // parameter whose owner is rhsSym, and which shares the name of an actual + // type parameter of rhsSym, but which is not among the type parameters of + // rhsSym. One can see examples of it at SI-4365. + val argIndex = rhsSym.typeParams indexWhere (lhsSym.name == _.name) + // don't be too zealous with the exceptions, see #2641 + if (argIndex < 0 && rhs.parents.exists(typeIsErroneous)) ErrorType - else - abort(s"something is wrong: cannot make sense of type application\n $lhs\n $rhs") + else { + // It's easy to get here when working on hardcore type machinery (not to + // mention when not doing so, see above) so let's provide a standout error. + def own_s(s: Symbol) = s.nameString + " in " + s.safeOwner.nameString + def explain = + sm"""| sought ${own_s(lhsSym)} + | classSym ${own_s(rhsSym)} + | tparams ${rhsSym.typeParams map own_s mkString ", "} + |""" + + if (argIndex < 0) + abort(s"Something is wrong: cannot find $lhs in applied type $rhs\n" + explain) + else { + val targ = rhsArgs(argIndex) + // @M! don't just replace the whole thing, might be followed by type application + val result = appliedType(targ, lhsArgs mapConserve this) + def msg = s"Created $result, though could not find ${own_s(lhsSym)} among tparams of ${own_s(rhsSym)}" + if (!rhsSym.typeParams.contains(lhsSym)) + devWarning(s"Inconsistent tparam/owner views: had to fall back on names\n$msg\n$explain") + + result + } + } } // 0) @pre: `classParam` is a class type parameter diff --git a/test/files/pos/t4365/a_1.scala b/test/files/pos/t4365/a_1.scala new file mode 100644 index 0000000000..6f3405b1ff --- /dev/null +++ b/test/files/pos/t4365/a_1.scala @@ -0,0 +1,18 @@ +import scala.collection._ + +trait SeqViewLike[+A, + +Coll, + +This <: SeqView[A, Coll] with SeqViewLike[A, Coll, This]] + extends Seq[A] with GenSeqViewLike[A, Coll, This] +{ + + trait Transformed[+B] extends super[GenSeqViewLike].Transformed[B] + + abstract class AbstractTransformed[+B] extends Seq[B] with Transformed[B] { + def underlying: Coll = error("") + } + + trait Reversed extends Transformed[A] with super[GenSeqViewLike].Reversed + + protected def newReversed: Transformed[A] = new AbstractTransformed[A] with Reversed +} diff --git a/test/files/pos/t4365/b_1.scala b/test/files/pos/t4365/b_1.scala new file mode 100644 index 0000000000..e5b5687185 --- /dev/null +++ b/test/files/pos/t4365/b_1.scala @@ -0,0 +1,22 @@ +import scala.collection._ + +trait GenSeqViewLike[+A, + +Coll, + +This <: GenSeqView[A, Coll] with GenSeqViewLike[A, Coll, This]] +extends GenSeq[A] { +self => + + trait Transformed[+B] { + def length: Int = 0 + def apply(idx: Int): B = error("") + } + + trait Reversed extends Transformed[A] { + def iterator: Iterator[A] = createReversedIterator + + private def createReversedIterator: Iterator[A] = { + self.foreach(_ => ()) + null + } + } +} |