diff options
author | Jason Zaugg <jzaugg@gmail.com> | 2013-03-05 09:57:35 +0100 |
---|---|---|
committer | Jason Zaugg <jzaugg@gmail.com> | 2013-03-05 18:41:05 +0100 |
commit | acd74cae0935d79cedbeb2bec719174b7cf54e5e (patch) | |
tree | 347a3a62a59fdf3d57fcee76e07a7b609437afae /test/files | |
parent | b98cc582fb8e06a6b7049e6688a80c8b38daba98 (diff) | |
download | scala-acd74cae0935d79cedbeb2bec719174b7cf54e5e.tar.gz scala-acd74cae0935d79cedbeb2bec719174b7cf54e5e.tar.bz2 scala-acd74cae0935d79cedbeb2bec719174b7cf54e5e.zip |
SI-7214 outer check based on dealiased pattern type.
A Typed Pattern (_: T) is more than `.isInstanceOf`: if `T` is a
path dependent type, the scrutinee's $outer reference is also
compared against the prefix of `T`.
The code that synthesises this is split into two places.
`needsOuterCheck` determines whether to add this check, based on
the type `T`, and the type of the scrutinee. If it gives the
go-ahead, `treeCondStrategy.outerCheck` synthesizes the check.
The new test case demonstrates the problems caused by the failure
to dealias in `needsOuterCheck`: it could either wrongly lead to
synthesis of an outer test (which would crash), or wrongly omit
the outer test (meaning overly liberal matching.)
A simple `dealias` remedies this. `dealiasWiden` is *not*
appropriate here; we need to keep hold of singleton types.
I'll also note that there is already a little slack between these
methods, as commented:
> ExplicitOuter replaces `Select(q, outerSym) OBJ_EQ expectedPrefix`
> by `Select(q, > outerAccessor(outerSym.owner)) OBJ_EQ expectedPrefix`
> if there's an outer accessor, otherwise the condition becomes `true`
> TODO: can we improve needsOuterTest so there's always an outerAccessor?
So this is probably a fragile area that warrants a careful review
with a view to design improvements.
Diffstat (limited to 'test/files')
-rw-r--r-- | test/files/run/t7214.scala | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/test/files/run/t7214.scala b/test/files/run/t7214.scala new file mode 100644 index 0000000000..ff1ea8082d --- /dev/null +++ b/test/files/run/t7214.scala @@ -0,0 +1,57 @@ +// pattern matcher crashes here trying to synthesize an uneeded outer test. +// no-symbol does not have an owner +// at scala.reflect.internal.SymbolTable.abort(SymbolTable.scala:49) +// at scala.tools.nsc.Global.abort(Global.scala:253) +// at scala.reflect.internal.Symbols$NoSymbol.owner(Symbols.scala:3248) +// at scala.reflect.internal.Symbols$Symbol.effectiveOwner(Symbols.scala:678) +// at scala.reflect.internal.Symbols$Symbol.isDefinedInPackage(Symbols.scala:664) +// at scala.reflect.internal.TreeGen.mkAttributedSelect(TreeGen.scala:188) +// at scala.reflect.internal.TreeGen.mkAttributedRef(TreeGen.scala:124) +// at scala.tools.nsc.ast.TreeDSL$CODE$.REF(TreeDSL.scala:308) +// at scala.tools.nsc.typechecker.PatternMatching$TreeMakers$TypeTestTreeMaker$treeCondStrategy$.outerTest(PatternMatching.scala:1209) +class Crash { + type Alias = C#T + + val c = new C + val t = new c.T + + // Crash via a Typed Pattern... + (t: Any) match { + case e: Alias => + } + + // ... or via a Typed Extractor Pattern. + object Extractor { + def unapply(a: Alias): Option[Any] = None + } + (t: Any) match { + case Extractor() => + case _ => + } + + // checking that correct outer tests are applied when + // aliases for path dependent types are involved. + val c2 = new C + type CdotT = c.T + type C2dotT = c2.T + + val outerField = t.getClass.getDeclaredFields.find(_.getName contains ("outer")).get + outerField.setAccessible(true) + + (t: Any) match { + case _: C2dotT => + println(s"!!! wrong match. t.outer=${outerField.get(t)} / c2 = $c2") // this matches on 2.10.0 + case _: CdotT => + case _ => + println(s"!!! wrong match. t.outer=${outerField.get(t)} / c = $c") + } +} + +class C { + class T +} + +object Test extends App { + new Crash +} + |