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author | Adriaan Moors <adriaan.moors@typesafe.com> | 2014-01-28 16:43:40 -0800 |
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committer | Adriaan Moors <adriaan.moors@typesafe.com> | 2014-02-19 10:12:19 -0800 |
commit | c001b888b896989a2c0afa0c24d038502970151c (patch) | |
tree | b04b54e08a8ad8f95db4e14d6509a044146ef1c5 /src/compiler/scala/reflect/reify | |
parent | 3dbcb1b9d4daa5cba98747bbc66f898ba0f864fd (diff) | |
download | scala-c001b888b896989a2c0afa0c24d038502970151c.tar.gz scala-c001b888b896989a2c0afa0c24d038502970151c.tar.bz2 scala-c001b888b896989a2c0afa0c24d038502970151c.zip |
SI-1503 don't assume unsound type for ident/literal patterns
The fix only kicks in under -Xfuture. We also warn under -Xlint.
What type should a variable bound to the value matched by a pattern have?
To avoid CCEs, it should be a type that's implied by the matching
semantics of the pattern.
Usually, the type implied by a pattern matching a certain value
is the pattern's type, because pattern matching implies instance-of checks.
However, Stable Identifier and Literal patterns are matched using `==`,
which does not imply a type for the binder that binds the matched value.
The change in type checking due to this fix is that programs that used to crash with a CCE
(because we blindly cast to the type of the pattern, which a `==` check does not imply)
now get a weaker type instead (and no cast). They may still type check, or they may not.
To compensate for this fix, change `case x@Foo => x` to `case x: Foo.type => x`,
if it's important that `x` have type `Foo.type`.
See also:
- SI-4577: matching of singleton type patterns uses `eq`,
not `==` (so that the types are not a lie).
- SI-5024: patmat strips unused bindings, but affects semantics
Diffstat (limited to 'src/compiler/scala/reflect/reify')
-rw-r--r-- | src/compiler/scala/reflect/reify/codegen/GenTypes.scala | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/compiler/scala/reflect/reify/codegen/GenTypes.scala b/src/compiler/scala/reflect/reify/codegen/GenTypes.scala index a90a3a338b..cfd3239015 100644 --- a/src/compiler/scala/reflect/reify/codegen/GenTypes.scala +++ b/src/compiler/scala/reflect/reify/codegen/GenTypes.scala @@ -34,9 +34,9 @@ trait GenTypes { if (tsym.isClass && tpe == tsym.typeConstructor && tsym.isStatic) Select(Select(reify(tsym), nme.asType), nme.toTypeConstructor) else tpe match { - case tpe @ NoType => + case tpe : NoType.type => reifyMirrorObject(tpe) - case tpe @ NoPrefix => + case tpe : NoPrefix.type => reifyMirrorObject(tpe) case tpe @ ThisType(root) if root.isRoot => mirrorBuildCall(nme.thisPrefix, mirrorMirrorSelect(nme.RootClass)) |