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author | odersky <odersky@gmail.com> | 2015-10-25 13:39:10 +0100 |
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committer | odersky <odersky@gmail.com> | 2015-10-25 13:39:10 +0100 |
commit | ecf62cf18b43b5a39e973bdc8087675a24337ce0 (patch) | |
tree | 33619b5d8f9cf84797b547d7e2bf50c4fcb95dc7 /src | |
parent | 77f7b2a4e988aa610a3cf7d92bb8838359127176 (diff) | |
parent | 0a386a85da9c6df97bf2cb6627e1f905af17c123 (diff) | |
download | dotty-ecf62cf18b43b5a39e973bdc8087675a24337ce0.tar.gz dotty-ecf62cf18b43b5a39e973bdc8087675a24337ce0.tar.bz2 dotty-ecf62cf18b43b5a39e973bdc8087675a24337ce0.zip |
Merge pull request #843 from dotty-staging/fix-#830
Fix #830: Compiler hangs on implicit search with singleton &/|
Diffstat (limited to 'src')
-rw-r--r-- | src/dotty/tools/dotc/core/TypeComparer.scala | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/src/dotty/tools/dotc/core/TypeComparer.scala b/src/dotty/tools/dotc/core/TypeComparer.scala index f2a4c9e1e..1afaed60d 100644 --- a/src/dotty/tools/dotc/core/TypeComparer.scala +++ b/src/dotty/tools/dotc/core/TypeComparer.scala @@ -123,7 +123,7 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling { pendingSubTypes = new mutable.HashSet[(Type, Type)] ctx.log(s"!!! deep subtype recursion involving ${tp1.show} <:< ${tp2.show}, constraint = ${state.constraint.show}") ctx.log(s"!!! constraint = ${constraint.show}") - assert(!ctx.settings.YnoDeepSubtypes.value) + if (ctx.settings.YnoDeepSubtypes.value) throw new Error("deep subtype") if (Config.traceDeepSubTypeRecursions && !this.isInstanceOf[ExplainingTypeComparer]) ctx.log(TypeComparer.explained(implicit ctx => ctx.typeComparer.isSubType(tp1, tp2))) } @@ -779,8 +779,24 @@ class TypeComparer(initctx: Context) extends DotClass with ConstraintHandling { else { val t2 = mergeIfSub(tp2, tp1) if (t2.exists) t2 - else andType(tp1, tp2) - } + else tp1 match { + case tp1: ConstantType => + tp2 match { + case tp2: ConstantType => + // Make use of the fact that the intersection of two constant types + // types which are not subtypes of each other is known to be empty. + // Note: The same does not apply to singleton types in general. + // E.g. we could have a pattern match against `x.type & y.type` + // which might succeed if `x` and `y` happen to be the same ref + // at run time. It would not work to replace that with `Nothing`. + // However, maybe we can still apply the replacement to + // types which are not explicitly written. + defn.NothingType + case _ => andType(tp1, tp2) + } + case _ => andType(tp1, tp2) + } + } } } } |