diff options
| -rw-r--r-- | src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala | 4 | ||||
| -rw-r--r-- | test/files/neg/t6771b.check | 6 | ||||
| -rw-r--r-- | test/files/neg/t6771b.scala | 16 | ||||
| -rw-r--r-- | test/files/pos/t6771.flags | 1 | ||||
| -rw-r--r-- | test/files/pos/t6771.scala | 9 |
5 files changed, 35 insertions, 1 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala index d9f93f27b6..9558542533 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala @@ -99,7 +99,9 @@ trait TreeAndTypeAnalysis extends Debugging { // TODO: when type tags are available, we will check -- when this is implemented, can we take that into account here? // similar to typer.infer.approximateAbstracts object typeArgsToWildcardsExceptArray extends TypeMap { - def apply(tp: Type): Type = tp match { + // SI-6771 dealias would be enough today, but future proofing with the dealiasWiden. + // See neg/t6771b.scala for elaboration + def apply(tp: Type): Type = tp.dealiasWiden match { case TypeRef(pre, sym, args) if args.nonEmpty && (sym ne ArrayClass) => TypeRef(pre, sym, args map (_ => WildcardType)) case _ => diff --git a/test/files/neg/t6771b.check b/test/files/neg/t6771b.check new file mode 100644 index 0000000000..ba99e9178d --- /dev/null +++ b/test/files/neg/t6771b.check @@ -0,0 +1,6 @@ +t6771b.scala:14: error: type mismatch; + found : x.type (with underlying type String) + required: Test.a.type + b = b match { case x => x } + ^ +one error found diff --git a/test/files/neg/t6771b.scala b/test/files/neg/t6771b.scala new file mode 100644 index 0000000000..78f11f7750 --- /dev/null +++ b/test/files/neg/t6771b.scala @@ -0,0 +1,16 @@ +// Currently, the pattern matcher widens the type of the +// scrutinee, so this doesn't typecheck. This test just +// confirms this behaviour, although it would be an improvement +// to change this and make this a `pos` test. +// +// But, to the intrepid hacker who works on this, a few notes: +// You'll have to look into places in the pattern matcher that +// call `dealias`, and see if they need to be `dealiasWiden`. +// For example, if `checkableType` used only `dealias`, `pos/t6671.scala` +// would fail. +object Test { + val a = ""; var b: a.type = a + + b = b match { case x => x } +} + diff --git a/test/files/pos/t6771.flags b/test/files/pos/t6771.flags new file mode 100644 index 0000000000..e8fb65d50c --- /dev/null +++ b/test/files/pos/t6771.flags @@ -0,0 +1 @@ +-Xfatal-warnings
\ No newline at end of file diff --git a/test/files/pos/t6771.scala b/test/files/pos/t6771.scala new file mode 100644 index 0000000000..0f0bd4e4a0 --- /dev/null +++ b/test/files/pos/t6771.scala @@ -0,0 +1,9 @@ +object Test { + type Id[X] = X + val a: Id[Option[Int]] = None + + a match { + case Some(x) => println(x) + case None => + } +} |