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Fix #5494: Spurious unchecked warning when type testing an alias #8808

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Merged
merged 19 commits into from
Apr 29, 2020
Merged

Fix #5494: Spurious unchecked warning when type testing an alias #8808

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aeeb14b
Fix #5494: Spurious unchecked warning when type testing an alias
smarter Apr 27, 2020
3991198
Fix type test warning involving applied types
smarter Apr 27, 2020
b1a9fd7
Add unchecked marks for technically unsafe type tests
smarter Apr 27, 2020
7e30d84
Move tests
liufengyun Apr 28, 2020
d61eb85
Handle GADT bounds in isInstanceOf type test
liufengyun Apr 28, 2020
77bd0cc
Add test
liufengyun Apr 28, 2020
891db3c
Restore original spec
liufengyun Apr 28, 2020
2531e18
Add test for Tree | Context => Tree
liufengyun Apr 28, 2020
58f506b
Add missing variance annotation
liufengyun Apr 28, 2020
10169b1
Add test for Tree | (Context => Tree)
liufengyun Apr 28, 2020
31c751f
Fix unchecked warnings in compiler
liufengyun Apr 28, 2020
77e96cd
Fix typo in comment
liufengyun Apr 28, 2020
b5ae277
Fix unchecked warning in language server
liufengyun Apr 28, 2020
1cb965a
Add more test case
liufengyun Apr 28, 2020
2e028af
Add documentation for code
liufengyun Apr 28, 2020
33094bf
Address review: add comment
liufengyun Apr 29, 2020
fb672e5
Address review: rename isClassDetermined to typeArgsTrivial
liufengyun Apr 29, 2020
4a5ab5a
Address review: code refactoring
liufengyun Apr 29, 2020
841d191
Add test case for type lambda
liufengyun Apr 29, 2020
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6 changes: 3 additions & 3 deletions compiler/src/dotty/tools/dotc/ast/Trees.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -503,7 +503,7 @@ object Trees {
type ThisTree[-T >: Untyped] = If[T]
def isInline = false
}
class InlineIf[T >: Untyped] private[ast] (cond: Tree[T], thenp: Tree[T], elsep: Tree[T])(implicit @constructorOnly src: SourceFile)
class InlineIf[-T >: Untyped] private[ast] (cond: Tree[T], thenp: Tree[T], elsep: Tree[T])(implicit @constructorOnly src: SourceFile)
extends If(cond, thenp, elsep) {
override def isInline = true
override def toString = s"InlineIf($cond, $thenp, $elsep)"
Expand All @@ -529,7 +529,7 @@ object Trees {
type ThisTree[-T >: Untyped] = Match[T]
def isInline = false
}
class InlineMatch[T >: Untyped] private[ast] (selector: Tree[T], cases: List[CaseDef[T]])(implicit @constructorOnly src: SourceFile)
class InlineMatch[-T >: Untyped] private[ast] (selector: Tree[T], cases: List[CaseDef[T]])(implicit @constructorOnly src: SourceFile)
extends Match(selector, cases) {
override def isInline = true
override def toString = s"InlineMatch($selector, $cases)"
Expand Down Expand Up @@ -579,7 +579,7 @@ object Trees {
}

/** Array(elems) */
class JavaSeqLiteral[T >: Untyped] private[ast] (elems: List[Tree[T]], elemtpt: Tree[T])(implicit @constructorOnly src: SourceFile)
class JavaSeqLiteral[-T >: Untyped] private[ast] (elems: List[Tree[T]], elemtpt: Tree[T])(implicit @constructorOnly src: SourceFile)
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This is good for uniformity but why would this make any difference for type test safety warnings ?

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The following code shows why it matters:

trait Tree[-T]

class JavaSeqLiteral[T] extends Tree[T]

trait Type

class DummyTree extends JavaSeqLiteral[Any]

def foo1(tree: Tree[Type]) =
  tree.isInstanceOf[JavaSeqLiteral[Type]]   // error

foo1(new DummyTree)

extends SeqLiteral(elems, elemtpt) {
override def toString: String = s"JavaSeqLiteral($elems, $elemtpt)"
}
Expand Down