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author | Adriaan Moors <adriaan@lightbend.com> | 2016-11-30 17:45:59 -0800 |
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committer | GitHub <noreply@github.com> | 2016-11-30 17:45:59 -0800 |
commit | c2eb299b0e1ed2f321a81d4afbdb36762e2c0e7b (patch) | |
tree | b184b8e08dc9077a39b4f48e86e5e4959ffb3c01 /test/files/run/t7046-2/Macros_1.scala | |
parent | 038c15e405b9498863a2236707686a7933748c60 (diff) | |
parent | dde13b56f421a6f956abebc58f041acec8744149 (diff) | |
download | scala-c2eb299b0e1ed2f321a81d4afbdb36762e2c0e7b.tar.gz scala-c2eb299b0e1ed2f321a81d4afbdb36762e2c0e7b.tar.bz2 scala-c2eb299b0e1ed2f321a81d4afbdb36762e2c0e7b.zip |
Merge pull request #5284 from milessabin/topic/si-7046
SI-7046 reflection doesn't see all knownDirectSubclasses
This appears to do the right thing in the most typical scenarios in which `knownDirectSubclasses` would be used. The missing 5% is that subclasses defined in local scopes might not be seen by `knownDirectSubclasses` (see `Local` and `Riddle` in the test below). In mitigation, though, it is almost certain that a local subclass would represent an error in any scenario where `knownDirectSubclasses` might be used.
Errors for such situations are reported by recording (via a symbol attachment) that `knownDirectSubclasses` has been called and reporting an error if any additional children are added subsequently.
Despite these limitations and caveats, I believe that this represents a huge improvement over the status quo, and would eliminate 100% of the failures that I've seen in practice with people using shapeless for type class derivation.
Diffstat (limited to 'test/files/run/t7046-2/Macros_1.scala')
-rw-r--r-- | test/files/run/t7046-2/Macros_1.scala | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/test/files/run/t7046-2/Macros_1.scala b/test/files/run/t7046-2/Macros_1.scala new file mode 100644 index 0000000000..2a5bf82f62 --- /dev/null +++ b/test/files/run/t7046-2/Macros_1.scala @@ -0,0 +1,15 @@ +import scala.language.experimental.macros +import scala.reflect.macros.blackbox.Context + +object Macros { + def impl[T](c: Context)(implicit ttag: c.WeakTypeTag[T]): c.Expr[List[String]] = { + import c.universe._; + val ttpe = ttag.tpe + val tsym = ttpe.typeSymbol.asClass + val subclasses = tsym.knownDirectSubclasses.toList.map(_.name.toString) + + c.Expr[List[String]](q"$subclasses") + } + + def knownDirectSubclasses[T]: List[String] = macro impl[T] +} |