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author | Paul Phillips <paulp@improving.org> | 2013-06-04 11:50:05 -0700 |
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committer | Paul Phillips <paulp@improving.org> | 2013-06-04 12:25:43 -0700 |
commit | 2f0e5ec1e96a6e4806841069736eda844d3a8dd6 (patch) | |
tree | 1a72792e2f08519f51e444e98eb19ffa2a855168 /test/files/neg/t6889.check | |
parent | 803d451a28824af17f0cab446e4c76f51003fd01 (diff) | |
download | scala-2f0e5ec1e96a6e4806841069736eda844d3a8dd6.tar.gz scala-2f0e5ec1e96a6e4806841069736eda844d3a8dd6.tar.bz2 scala-2f0e5ec1e96a6e4806841069736eda844d3a8dd6.zip |
SI-6899, prohibit dangerous, useless implicit conversions.
Increase eligibility requirements for implicit conversions,
such that T => U is ineligible if
T <: Null <or> AnyRef <: U
This has the salutary effect of allowing us to ditch 16
ridiculous implicits from Predef, since they existed solely
to work around the absence of this restriction.
There was one tiny impact on actual source code (one line
in one file) shown here, necessitated because the literal null
is not eligible to be implicitly converted to A via <:<.
def f[A](implicit ev: Null <:< A): A = null // before
def f[A](implicit ev: Null <:< A): A = ev(null) // after
As impositions go it's on the tame side.
Diffstat (limited to 'test/files/neg/t6889.check')
-rw-r--r-- | test/files/neg/t6889.check | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/test/files/neg/t6889.check b/test/files/neg/t6889.check new file mode 100644 index 0000000000..a77e8a010c --- /dev/null +++ b/test/files/neg/t6889.check @@ -0,0 +1,7 @@ +t6889.scala:16: error: the result type of an implicit conversion must be more specific than AnyRef + def f(x: Dingo): AnyRef = x // fail - no conversion to AnyRef + ^ +t6889.scala:17: error: an expression of type Null is ineligible for implicit conversion + var x: Int = null // fail - no conversion from Null + ^ +two errors found |