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oderskyKordyjan
odersky
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Kordyjan
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Use experimental language import to enable the new behavior
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12 files changed

+96
-23
lines changed

12 files changed

+96
-23
lines changed

‎compiler/src/dotty/tools/dotc/config/Feature.scala‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -33,6 +33,7 @@ object Feature:
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val pureFunctions = experimental("pureFunctions")
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val captureChecking = experimental("captureChecking")
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val into = experimental("into")
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val avoidLoopingGivens = experimental("avoidLoopingGivens")
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val globalOnlyImports: Set[TermName] = Set(pureFunctions, captureChecking)
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‎compiler/src/dotty/tools/dotc/semanticdb/Scala3.scala‎

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Original file line numberDiff line numberDiff line change
@@ -77,6 +77,9 @@ object Scala3:
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type SemanticSymbol = Symbol | FakeSymbol
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given SemanticSymbolOps : AnyRef with
80+
import SymbolOps.*
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import StringOps.*
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extension (sym: SemanticSymbol)
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def name(using Context): Name = sym match
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case s: Symbol => s.name

‎compiler/src/dotty/tools/dotc/typer/Implicits.scala‎

Lines changed: 34 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -1589,19 +1589,40 @@ trait Implicits:
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15901590
val eligible = if contextual then preEligible.filterNot(comesTooLate) else preEligible
15911591

1592-
def checkResolutionChange(result: SearchResult) = result match
1593-
case result: SearchSuccess
1594-
if (eligible ne preEligible) && !sourceVersion.isAtLeast(SourceVersion.`future`) =>
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searchImplicit(preEligible.diff(eligible), contextual) match
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case prevResult: SearchSuccess =>
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report.error(
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em"""Warning: result of implicit search for $pt will change.
1599-
|current result: ${prevResult.ref.symbol.showLocated}
1600-
|result with -source future: ${result.ref.symbol.showLocated}""",
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srcPos
1602-
)
1603-
case _ =>
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case _ =>
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def checkResolutionChange(result: SearchResult) =
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if (eligible ne preEligible)
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&& !Feature.enabled(Feature.avoidLoopingGivens)
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then searchImplicit(preEligible.diff(eligible), contextual) match
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case prevResult: SearchSuccess =>
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def remedy = pt match
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case _: SelectionProto =>
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"conversion,\n - use an import to get extension method into scope"
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case _: ViewProto =>
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"conversion"
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case _ =>
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"argument"
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def showResult(r: SearchResult) = r match
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case r: SearchSuccess => ctx.printer.toTextRef(r.ref).show
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case r => r.show
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result match
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case result: SearchSuccess if prevResult.ref frozen_=:= result.ref =>
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// OK
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case _ =>
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report.error(
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em"""Warning: result of implicit search for $pt will change.
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|Current result ${showResult(prevResult)} will be no longer eligible
1616+
| because it is not defined before the search position.
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|Result with new rules: ${showResult(result)}.
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|To opt into the new rules, use the `avoidLoopingGivens` language import,
1619+
|
1620+
|To fix the problem you could try one of the following:
1621+
| - rearrange definitions,
1622+
| - use an explicit $remedy.""",
1623+
srcPos)
1624+
case _ =>
1625+
end checkResolutionChange
16051626

16061627
searchImplicit(eligible, contextual) match
16071628
case result: SearchSuccess =>

‎compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1781,6 +1781,8 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
17811781
end TypeRepr
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17831783
given TypeReprMethods: TypeReprMethods with
1784+
import SymbolMethods.*
1785+
17841786
extension (self: TypeRepr)
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def show(using printer: Printer[TypeRepr]): String = printer.show(self)
@@ -2608,6 +2610,8 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
26082610
end Symbol
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26102612
given SymbolMethods: SymbolMethods with
2613+
import FlagsMethods.*
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26112615
extension (self: Symbol)
26122616
def owner: Symbol = self.denot.owner
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def maybeOwner: Symbol = self.denot.maybeOwner

‎library/src/scala/runtime/stdLibPatches/language.scala‎

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Original file line numberDiff line numberDiff line change
@@ -91,6 +91,15 @@ object language:
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@compileTimeOnly("`into` can only be used at compile time in import statements")
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object into
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94+
/** Experimental support for new given resolution rules that avoid looping
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* givens. By the new rules, a given may not implicitly use itself or givens
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* defined after it.
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*
98+
* @see [[https://dotty.epfl.ch/docs/reference/experimental/avoid-looping-givens]]
99+
*/
100+
@compileTimeOnly("`avoidLoopingGivens` can only be used at compile time in import statements")
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object avoidLoopingGivens
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94103
/** Was needed to add support for relaxed imports of extension methods.
95104
* The language import is no longer needed as this is now a standard feature since SIP was accepted.
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* @see [[http://dotty.epfl.ch/docs/reference/contextual/extension-methods]]

‎tests/neg/i15474.check‎

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,12 @@
11
-- Error: tests/neg/i15474.scala:16:56 ---------------------------------------------------------------------------------
22
16 | given Ordering[Price] = summon[Ordering[BigDecimal]] // error
33
| ^
4-
| Warning: result of implicit search for Ordering[BigDecimal] will change.
5-
| current result: given instance given_Ordering_Price in object Price
6-
| result with -source future: object BigDecimal in object Ordering
4+
| Warning: result of implicit search for Ordering[BigDecimal] will change.
5+
| Current result Prices.Price.given_Ordering_Price will be no longer eligible
6+
| because it is not defined before the search position.
7+
| Result with new rules: scala.math.Ordering.BigDecimal.
8+
| To opt into the new rules, use the `avoidLoopingGivens` language import,
9+
|
10+
| To fix the problem you could try one of the following:
11+
| - rearrange definitions,
12+
| - use an explicit argument.

‎tests/neg/i6716.check‎

Lines changed: 8 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2,5 +2,11 @@
22
12 | given Monad[Bar] = summon[Monad[Foo]] // error
33
| ^
44
| Warning: result of implicit search for Monad[Foo] will change.
5-
| current result: given instance given_Monad_Bar in object Bar
6-
| result with -source future: object given_Monad_Foo in object Foo
5+
| Current result Bar.given_Monad_Bar will be no longer eligible
6+
| because it is not defined before the search position.
7+
| Result with new rules: Foo.given_Monad_Foo.
8+
| To opt into the new rules, use the `avoidLoopingGivens` language import,
9+
|
10+
| To fix the problem you could try one of the following:
11+
| - rearrange definitions,
12+
| - use an explicit argument.

‎tests/neg/i7294-a.check‎

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
-- Error: tests/neg/i7294-a.scala:6:10 ---------------------------------------------------------------------------------
2+
6 | case x: T => x.g(10) // error // error
3+
| ^
4+
| Warning: result of implicit search for scala.reflect.TypeTest[Nothing, T] will change.
5+
| Current result foo.i7294-a$package.f will be no longer eligible
6+
| because it is not defined before the search position.
7+
| Result with new rules: No Matching Implicit.
8+
| To opt into the new rules, use the `avoidLoopingGivens` language import,
9+
|
10+
| To fix the problem you could try one of the following:
11+
| - rearrange definitions,
12+
| - use an explicit argument.
13+
|
14+
| where: T is a type in given instance f with bounds <: foo.Foo
15+
-- [E007] Type Mismatch Error: tests/neg/i7294-a.scala:6:15 ------------------------------------------------------------
16+
6 | case x: T => x.g(10) // error // error
17+
| ^
18+
| Found: (x : Nothing)
19+
| Required: ?{ g: ? }
20+
| Note that implicit conversions were not tried because the result of an implicit conversion
21+
| must be more specific than ?{ g: [applied to (10) returning T] }
22+
|
23+
| longer explanation available when compiling with `-explain`

‎tests/neg/i7294-a.scala‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@ package foo
33
trait Foo { def g(x: Int): Any }
44

55
inline given f[T <: Foo]: T = ??? match {
6-
case x: T => x.g(10) // error
6+
case x: T => x.g(10) // error // error
77
}
88

99
@main def Test = f

‎tests/neg/i7294-b.scala‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@ package foo
33
trait Foo { def g(x: Any): Any }
44

55
inline given f[T <: Foo]: T = ??? match {
6-
case x: T => x.g(10) // error
6+
case x: T => x.g(10) // error // error
77
}
88

99
@main def Test = f

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