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Improve warning for wildcard matching non-nullable types (scala#21577) #21623
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Original file line number | Diff line number | Diff line change |
---|---|---|
|
@@ -928,7 +928,11 @@ object SpaceEngine { | |
&& isSubspace(covered, prev) | ||
then { | ||
val nullOnly = isNullable && i == len - 1 && isWildcardArg(pat) | ||
val msg = if nullOnly then MatchCaseOnlyNullWarning() else MatchCaseUnreachable() | ||
val wildcardNotNullable = i == len - 1 && isWildcardArg(pat) | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I don't think this will work. It will catch other cases which are not related to |
||
val msg = | ||
if nullOnly then MatchCaseOnlyNullWarning() | ||
else if wildcardNotNullable then MatchCaseNonNullableWildcardWarning() | ||
else MatchCaseUnreachable() | ||
report.warning(msg, pat.srcPos) | ||
} | ||
deferred = Nil | ||
|
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,8 @@ | ||
-- [E202] Pattern Match Warning: tests/explicit-nulls/warn/i21577.scala:5:9 -------------------------------------------- | ||
5 | case _ => println(2) // warn | ||
| ^ | ||
| Unreachable case (if expression is expected to be nullable, consider giving it a nullable type annotation). | ||
-- [E202] Pattern Match Warning: tests/explicit-nulls/warn/i21577.scala:12:11 ------------------------------------------ | ||
12 | case _ => println(2) // warn | ||
| ^ | ||
| Unreachable case (if expression is expected to be nullable, consider giving it a nullable type annotation). |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,24 @@ | ||
def f(s: String) = | ||
val s2 = s.trim() | ||
s2 match | ||
case s3: String => println(1) | ||
case _ => println(2) // warn | ||
|
||
|
||
def f2(s: String | Null) = | ||
val s2 = s.nn.trim() | ||
s2 match | ||
case s3: String => println(1) | ||
case _ => println(2) // warn | ||
|
||
def f3(s: String | Null) = | ||
val s2 = s | ||
s2 match | ||
case s3: String => println(1) | ||
case _ => println(2) | ||
|
||
def f4(s: String | Int) = | ||
val s2 = s | ||
s2 match | ||
case s3: String => println(1) | ||
case _ => println(2) |
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Why do we need another error?