Switch mapping of context bounds to using clauses in 3.6

Was future before.

Author: odersky

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -300,7 +300,7 @@ object desugar {
       // implicit resolution in Scala 3.
 
     val paramssNoContextBounds =
-      val iflag = if Feature.sourceVersion.isAtLeast(`future`) then Given else Implicit
+      val iflag = if Feature.sourceVersion.isAtLeast(`3.6`) then Given else Implicit
       val flags = if isPrimaryConstructor then iflag | LocalParamAccessor else iflag | Param
       mapParamss(paramss) {
         tparam => desugarContextBounds(tparam, evidenceParamBuf, flags, freshName, paramss)

tests/neg/ctx-bounds-priority-migration.scala

@@ -0,0 +1,13 @@
+//> using options -source 3.5
+trait Eq[A]
+trait Order[A] extends Eq[A]:
+  def toOrdering: Ordering[A]
+
+def f[Element: Eq: Order] = summon[Eq[Element]].toOrdering // ok
+
+def Test() =
+  val eq: Eq[Int] = ???
+  val ord: Order[Int] = ???
+  f(eq, ord)  // error
+  f(using eq, ord) // ok
+

tests/neg/ctx-bounds-priority.scala

@@ -0,0 +1,6 @@
+//> using options -source 3.6
+trait Eq[A]
+trait Order[A] extends Eq[A]:
+  def toOrdering: Ordering[A]
+
+def Test[Element: Eq: Order] = summon[Eq[Element]].toOrdering // error

tests/neg/i10901.check

@@ -1,23 +1,23 @@
 -- [E008] Not Found Error: tests/neg/i10901.scala:45:38 ----------------------------------------------------------------
 45 |    val pos1: Point2D[Int,Double] = x º y       // error
    |                                    ^^^
-   |       value º is not a member of object BugExp4Point2D.IntT.
-   |       An extension method was tried, but could not be fully constructed:
-   |
-   |           º(x)
-   |
-   |           failed with:
-   |
-   |               Ambiguous overload. The overloaded alternatives of method º in object dsl with types
-   |                [T1, T2]
-   |                 (x: BugExp4Point2D.ColumnType[T1])
-   |                   (y: BugExp4Point2D.ColumnType[T2])
-   |                     (implicit evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
-   |                [T1, T2]
-   |                 (x: T1)
-   |                   (y: BugExp4Point2D.ColumnType[T2])
-   |                     (implicit evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
-   |               both match arguments ((x : BugExp4Point2D.IntT.type))((y : BugExp4Point2D.DoubleT.type))
+   |          value º is not a member of object BugExp4Point2D.IntT.
+   |          An extension method was tried, but could not be fully constructed:
+   |
+   |              º(x)
+   |
+   |              failed with:
+   |
+   |                  Ambiguous overload. The overloaded alternatives of method º in object dsl with types
+   |                   [T1, T2]
+   |                    (x: BugExp4Point2D.ColumnType[T1])
+   |                      (y: BugExp4Point2D.ColumnType[T2])
+   |                        (using evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
+   |                   [T1, T2]
+   |                    (x: T1)
+   |                      (y: BugExp4Point2D.ColumnType[T2])
+   |                        (using evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
+   |                  both match arguments ((x : BugExp4Point2D.IntT.type))((y : BugExp4Point2D.DoubleT.type))
 -- [E008] Not Found Error: tests/neg/i10901.scala:48:38 ----------------------------------------------------------------
 48 |    val pos4: Point2D[Int,Double] = x º 201.1   // error
    |                                    ^^^
@@ -31,8 +31,8 @@
    |        Ambiguous overload. The overloaded alternatives of method º in object dsl with types
    |         [T1, T2]
    |          (x: BugExp4Point2D.ColumnType[T1])
-   |            (y: T2)(implicit evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
-   |         [T1, T2](x: T1)(y: T2)(implicit evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
+   |            (y: T2)(using evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
+   |         [T1, T2](x: T1)(y: T2)(using evidence$1: Numeric[T1], evidence$2: Numeric[T2]): BugExp4Point2D.Point2D[T1, T2]
    |        both match arguments ((x : BugExp4Point2D.IntT.type))((201.1d : Double))
 -- [E008] Not Found Error: tests/neg/i10901.scala:62:16 ----------------------------------------------------------------
 62 |  val y = "abc".foo  // error

tests/pos/i20901/Foo.tastycheck

@@ -74,7 +74,7 @@ Trees (98 bytes, starting from <elided base index>):
     61:                 SHAREDtype 6
     63:             IDENTtpt 16 [T]
     65:               TYPEREFdirect 39
-    67:           IMPLICIT
+    67:           GIVEN
     68:         IDENTtpt 17 [Nothing]
     70:           TYPEREF 17 [Nothing]
     72:             TERMREFpkg 2 [scala]