Drop syntax sugar for capture set member

scala · Nov 30, 2024 · f8893e5 · f8893e5
1 parent 5a901f4
commit f8893e5
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Showing 6 changed files with 24 additions and 21 deletions.
diff --git a/compiler/src/dotty/tools/dotc/cc/CaptureRef.scala b/compiler/src/dotty/tools/dotc/cc/CaptureRef.scala
@@ -143,6 +143,9 @@ trait CaptureRef extends TypeProxy, ValueType:
           || viaInfo(y.info)(subsumingRefs(this, _))
         case MaybeCapability(y1) => this.stripMaybe.subsumes(y1)
         case y: TypeRef if y.derivesFrom(defn.Caps_CapSet) =>
+          // The upper and lower bounds don't have to be in the form of `CapSet^{...}`.
+          // They can be other capture set variables, which are bounded by `CapSet`,
+          // like `def test[X^, Y^, Z >: X <: Y]`.
           y.info match
             case TypeBounds(_, hi: CaptureRef) => this.subsumes(hi)
             case _ => y.captureSetOfInfo.elems.forall(this.subsumes)

diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -4057,11 +4057,8 @@ object Parsers {
               || sourceVersion.isAtLeast(`3.6`) && in.isColon =>
             makeTypeDef(typeAndCtxBounds(tname))
           case _ =>
-            if in.isIdent(nme.UPARROW) && Feature.ccEnabled then
-              makeTypeDef(typeAndCtxBounds(tname))
-            else
-              syntaxErrorOrIncomplete(ExpectedTypeBoundOrEquals(in.token))
-              return EmptyTree // return to avoid setting the span to EmptyTree
+            syntaxErrorOrIncomplete(ExpectedTypeBoundOrEquals(in.token))
+            return EmptyTree // return to avoid setting the span to EmptyTree
         }
       }
     }

diff --git a/tests/neg-custom-args/captures/capture-poly.scala b/tests/neg-custom-args/captures/capture-poly.scala
@@ -3,7 +3,7 @@ import caps.*
 trait Foo extends Capability
 
 trait CaptureSet:
-  type C^
+  type C >: CapSet <: CapSet^
 
 def capturePoly[C^](a: Foo^{C^}): Foo^{C^} = a
 def capturePoly2(c: CaptureSet)(a: Foo^{c.C^}): Foo^{c.C^} = a

diff --git a/tests/neg-custom-args/captures/i21614.check b/tests/neg-custom-args/captures/i21614.check
@@ -1,15 +1,15 @@
--- [E007] Type Mismatch Error: tests/neg-custom-args/captures/i21614.scala:9:33 ----------------------------------------
-9 |  files.map((f: F) => new Logger(f)) // error, Q: can we make this pass (see #19076)?
-  |                                 ^
-  |                                 Found:    (f : F^)
-  |                                 Required: File^
-  |
-  | longer explanation available when compiling with `-explain`
--- [E007] Type Mismatch Error: tests/neg-custom-args/captures/i21614.scala:12:12 ---------------------------------------
-12 |  files.map(new Logger(_)) // error, Q: can we improve the error message?
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/i21614.scala:12:33 ---------------------------------------
+12 |  files.map((f: F) => new Logger(f)) // error, Q: can we make this pass (see #19076)?
+   |                                 ^
+   |                                 Found:    (f : F^)
+   |                                 Required: File^
+   |
+   | longer explanation available when compiling with `-explain`
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/i21614.scala:15:12 ---------------------------------------
+15 |  files.map(new Logger(_)) // error, Q: can we improve the error message?
    |            ^^^^^^^^^^^^^
-   |     Found:    (_$1: box File^{files*}) ->{files*} (ex$13: caps.Exists) -> box Logger{val f: File^{_$1}}^{ex$13}
-   |     Required: (_$1: box File^{files*}) -><fluid> box Logger{val f: File^?}^?
+   |     Found:    (_$1: box File^{files*}) ->{files*} (ex$16: caps.Exists) -> box Logger{val f: File^{_$1}}^{ex$16}
+   |     Required: (_$1: box File^{files*}) => box Logger{val f: File^?}^?
    |
    |     Note that the universal capability `cap`
    |     cannot be included in capture set ?

diff --git a/tests/neg-custom-args/captures/i21614.scala b/tests/neg-custom-args/captures/i21614.scala
@@ -2,6 +2,9 @@ import language.experimental.captureChecking
 import caps.Capability
 import caps.use
 
+trait List[+T]:
+  def map[U](f: T => U): List[U]
+
 trait File extends Capability
 class Logger(f: File^) extends Capability // <- will work if we remove the extends clause
 

diff --git a/tests/neg-custom-args/captures/i21868.scala b/tests/neg-custom-args/captures/i21868.scala
@@ -5,9 +5,9 @@ trait AbstractWrong:
   def f(): Unit^{C^} // error
 
 trait Abstract1:
-  type C^
+  type C >: CapSet <: CapSet^
   def f(): Unit^{C^}
 
-class Abstract2:
-  type C >: CapSet <: CapSet^
-  def f(): Unit^{C^}
+// class Abstract2:
+//   type C^
+//   def f(): Unit^{C^}