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author | Jason Zaugg <jzaugg@gmail.com> | 2014-11-09 18:29:35 +1000 |
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committer | Jason Zaugg <jzaugg@gmail.com> | 2014-11-09 18:38:21 +1000 |
commit | 90a98f7c41cfcfdb60dc25db5ac33d0d0ff10f99 (patch) | |
tree | 0f948e0ee75d048164122d285c148910ab2eb033 /test/files/pos | |
parent | b431a4bd83d3bfb2b95d0426d2905b34ce1265ad (diff) | |
download | scala-90a98f7c41cfcfdb60dc25db5ac33d0d0ff10f99.tar.gz scala-90a98f7c41cfcfdb60dc25db5ac33d0d0ff10f99.tar.bz2 scala-90a98f7c41cfcfdb60dc25db5ac33d0d0ff10f99.zip |
SI-5639 Fix spurious discarding of implicit import
In Scala fa0cdc7b (just before 2.9.0), a regression in implicit
search, SI-2866, was discovered by Lift and fixed. The nature of
the regression was that an in-scope, non-implicit symbol failed to
shadow an eponymous implicit import.
The fix for this introduced `isQualifyingImplicit` which discards
in-scope implicits when the current `Context`'s scope contains
a name-clashing entry.
Incidentally, this proved to be a shallow solution, and we later
improved shadowing detection in SI-4270 / 9129cfe9. That picked
up cases where a locally defined symbol in an intervening scope
shadowed an implicit.
This commit includes the test case from the comments of SI-2866.
Part of it is tested as a neg test (to test reporting of ambiguities),
and the rest is tested in a run test (to test which implicits are
picked.)
However, in the test case of SI-5639, we see that the scope lookup
performend by `isQualifyingImplicit` is fooled by a "ghost" module
symbol. The apparition I'm referring to is entered when
`initializeFromClassPath` / `enterClassAndModule` encounters
a class file named 'Baz.class', and speculatively enters _both_ a
class and module symbol. AFAIK, this is done to defer parsing the
class file to determine what inside. If it happens to be a Java
compiled class, the module symbol is needed to house the static
members.
This commit adds a condition that `Symbol#exists` which shines a torch
(forces the info) in the direction of the ghost module symbol. In our
test, this causes it to vanish, as we only need a class symbol for
the Scala defined `class Baz`.
The existing `pos` test for this actually did not exercise the bug,
separate compilation is required. It was originally checked in to
`pending` with this error, and then later moved to `pos` when someone
noticed it was not failing.
Diffstat (limited to 'test/files/pos')
-rw-r--r-- | test/files/pos/t5639/A_1.scala | 17 | ||||
-rw-r--r-- | test/files/pos/t5639/A_2.scala | 11 | ||||
-rw-r--r-- | test/files/pos/t5639/Bar.scala | 7 | ||||
-rw-r--r-- | test/files/pos/t5639/Foo.scala | 7 |
4 files changed, 28 insertions, 14 deletions
diff --git a/test/files/pos/t5639/A_1.scala b/test/files/pos/t5639/A_1.scala new file mode 100644 index 0000000000..c5da10eae4 --- /dev/null +++ b/test/files/pos/t5639/A_1.scala @@ -0,0 +1,17 @@ +import Implicits._ + +class Baz + +object Test { + implicitly[Int] +} + +object Implicits { + implicit val Baz: Int = 0 + // This implicit was being ignored by `isQualifyingImplicit` + // if the classpath contained a class file for `class Baz`. + // This is because the package scope contains a speculative + // symbol for `object Baz` which is entered by `SymbolLoaders` + // before looking inside the class file. (A Java originated + // classfile results in the class/module symbol pair.) +} diff --git a/test/files/pos/t5639/A_2.scala b/test/files/pos/t5639/A_2.scala new file mode 100644 index 0000000000..2bb36273e0 --- /dev/null +++ b/test/files/pos/t5639/A_2.scala @@ -0,0 +1,11 @@ +import Implicits._ + +class Baz + +object Test { + implicitly[Int] +} + +object Implicits { + implicit val Baz: Int = 0 +} diff --git a/test/files/pos/t5639/Bar.scala b/test/files/pos/t5639/Bar.scala deleted file mode 100644 index f577500acd..0000000000 --- a/test/files/pos/t5639/Bar.scala +++ /dev/null @@ -1,7 +0,0 @@ -package pack.age - -import pack.age.Implicits._ - -object Quux { - def baz : Baz = 1 -} diff --git a/test/files/pos/t5639/Foo.scala b/test/files/pos/t5639/Foo.scala deleted file mode 100644 index 1a07734a8e..0000000000 --- a/test/files/pos/t5639/Foo.scala +++ /dev/null @@ -1,7 +0,0 @@ -package pack.age - -class Baz - -object Implicits { - implicit def Baz(n: Int): Baz = new Baz -} |