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author | Martin Odersky <odersky@gmail.com> | 2012-07-20 19:12:30 +0200 |
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committer | Adriaan Moors <adriaan.moors@epfl.ch> | 2012-07-23 09:39:11 +0200 |
commit | 5c5e8d4dcd151a6e2bf9e7c259c618b9b4eff00f (patch) | |
tree | be08a99fb120ab98e09f090ba4d3ec48e6049e8a /test/files/pos | |
parent | 7b62eeea86c62f5e068c366065f8f4c2e6624eb7 (diff) | |
download | scala-5c5e8d4dcd151a6e2bf9e7c259c618b9b4eff00f.tar.gz scala-5c5e8d4dcd151a6e2bf9e7c259c618b9b4eff00f.tar.bz2 scala-5c5e8d4dcd151a6e2bf9e7c259c618b9b4eff00f.zip |
SI-4881 infer variance from formals, then result
Changed behavior so that when determining the target variance of a method parameter,
the variance in formals comes first. If variance is still undecided by that,
the variance in the result type is used as a secondary criterion.
(This is also done when determining prototype type params.)
Diffstat (limited to 'test/files/pos')
-rw-r--r-- | test/files/pos/t4881.scala | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/test/files/pos/t4881.scala b/test/files/pos/t4881.scala new file mode 100644 index 0000000000..46cfad9793 --- /dev/null +++ b/test/files/pos/t4881.scala @@ -0,0 +1,31 @@ +class Contra[-T] +trait A +trait B extends A +trait C extends B + +// test improved variance inference: first try formals to see in which variance positions the type param appears; +// only when that fails to determine variance, look at result type +object Test { + def contraLBUB[a >: C <: A](): Contra[a] = null + def contraLB[a >: C](): Contra[a] = null + +{ + val x = contraLBUB() //inferred Contra[C] instead of Contra[A] + val x1: Contra[A] = x +} + +{ + val x = contraLB() //inferred Contra[C] instead of Contra[Any] + val x1: Contra[Any] = x +} + +{ + val x = contraLBUB // make sure it does the same thing as its ()-less counterpart + val x1: Contra[A] = x +} + +{ + val x = contraLB + val x1: Contra[Any] = x +} +} |