Change syntax of cap parameters and members

bracevac · bracevac · commit c69e850736f1 · 2025-04-01T00:42:19.000+02:00
`cap` is now a soft modifier and we abolish
separate cap lists.
diff --git a/compiler/src/dotty/tools/dotc/ast/untpd.scala b/compiler/src/dotty/tools/dotc/ast/untpd.scala
@@ -234,6 +234,8 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
 
     case class Tracked()(implicit @constructorOnly src: SourceFile) extends Mod(Flags.Tracked)
 
+    case class CaptureParam()(implicit @constructorOnly src: SourceFile) extends Mod(Flags.CaptureParam)
+
     /** Used under pureFunctions to mark impure function types `A => B` in `FunctionWithMods` */
     case class Impure()(implicit @constructorOnly src: SourceFile) extends Mod(Flags.Impure)
   }
diff --git a/compiler/src/dotty/tools/dotc/core/Flags.scala b/compiler/src/dotty/tools/dotc/core/Flags.scala
@@ -380,6 +380,9 @@ object Flags {
   /** Tracked modifier for class parameter / a class with some tracked parameters */
   val (Tracked @ _, _, Dependent @ _) = newFlags(46, "tracked")
 
+  /** Cap modifier for capture-set parameters and capture-set members */
+  val (_, _, CaptureParam @ _) = newFlags(47, "cap")
+
   // ------------ Flags following this one are not pickled ----------------------------------
 
   /** Symbol is not a member of its owner */
diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
diff --git a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
@@ -1209,7 +1209,7 @@ object Scanners {
 
     def isSoftModifier: Boolean =
       token == IDENTIFIER
-      && (softModifierNames.contains(name) || name == nme.erased && erasedEnabled || name == nme.tracked && trackedEnabled)
+      && (softModifierNames.contains(name) || name == nme.erased && erasedEnabled || name == nme.tracked && trackedEnabled || name == nme.cap && Feature.ccEnabled)
 
     def isSoftModifierInModifierPosition: Boolean =
       isSoftModifier && inModifierPosition()
diff --git a/tests/neg-custom-args/captures/capset-members.scala b/tests/neg-custom-args/captures/capset-members.scala
@@ -1,29 +1,29 @@
 import caps.*
 
-trait Abstract[X^]:
-  cap C >: X
+trait Abstract[cap X]:
+  cap type C >: {X}
   // Don't test the return type using Unit, because it is a pure type.
   def boom(): AnyRef^{C}
 
-class Concrete extends Abstract[CapSet^{}]:
-  cap C = {}
+class Concrete extends Abstract[{}]:
+  cap type C = {}
   // TODO: Why do we get error without the return type here?
   def boom(): AnyRef = new Object
 
-class Concrete2 extends Abstract[CapSet^{}]:
-  cap C = {}
+class Concrete2 extends Abstract[{}]:
+  cap type C = {}
   def boom(): AnyRef^ = new Object // error
 
-class Concrete3 extends Abstract[CapSet^{}]:
+class Concrete3 extends Abstract[{}]:
   def boom(): AnyRef = new Object
 
-class Concrete4(a: AnyRef^) extends Abstract[CapSet^{a}]:
-  cap C = {} // error
+class Concrete4(a: AnyRef^) extends Abstract[{a}]:
+  cap type C = {} // error
   def boom(): AnyRef^{a} = a // error
 
-class Concrete5(a: AnyRef^, b: AnyRef^) extends Abstract[CapSet^{a}]:
-  cap C = a
+class Concrete5(a: AnyRef^, b: AnyRef^) extends Abstract[{a}]:
+  cap type C = {a}
   def boom(): AnyRef^{b} = b // error
 
-class Concrete6(a: AnyRef^, b: AnyRef^) extends Abstract[CapSet^{a}]:
+class Concrete6(a: AnyRef^, b: AnyRef^) extends Abstract[{a}]:
   def boom(): AnyRef^{b} = b // error
diff --git a/tests/neg-custom-args/captures/capset-members2.check b/tests/neg-custom-args/captures/capset-members2.check
@@ -1,4 +1,4 @@
--- Error: tests/neg-custom-args/captures/capset-members2.scala:4:7 -----------------------------------------------------
-4 |  cap C[T] // error
-  |       ^
-  |       'cap' declarations cannot have type parameters
+-- Error: tests/neg-custom-args/captures/capset-members2.scala:4:12 ----------------------------------------------------
+4 |  cap type C[T] // error
+  |            ^
+  |            'cap type' declarations cannot have type parameters
diff --git a/tests/neg-custom-args/captures/capset-members2.scala b/tests/neg-custom-args/captures/capset-members2.scala
@@ -1,5 +1,5 @@
 import caps.*
 
 trait Foo:
-  cap C[T] // error
+  cap type C[T] // error
 
diff --git a/tests/neg-custom-args/captures/capset-members3.check b/tests/neg-custom-args/captures/capset-members3.check
@@ -1,6 +1,6 @@
--- [E209] Syntax Error: tests/neg-custom-args/captures/capset-members3.scala:4:8 ---------------------------------------
-4 |  cap C _ // error
-  |        ^
-  |        =, >:, or <: expected, but '_' found
+-- [E209] Syntax Error: tests/neg-custom-args/captures/capset-members3.scala:4:13 --------------------------------------
+4 |  cap type C _ // error
+  |             ^
+  |             =, >:, or <: expected, but '_' found
   |
   | longer explanation available when compiling with `-explain`
diff --git a/tests/neg-custom-args/captures/capset-members3.scala b/tests/neg-custom-args/captures/capset-members3.scala
@@ -1,5 +1,5 @@
 import caps.*
 
 trait Foo:
-  cap C _ // error
+  cap type C _ // error
 
diff --git a/tests/pending/cap-paramlists8.scala b/tests/pending/cap-paramlists8.scala
@@ -7,4 +7,4 @@ def test =
   val y: Any^ = ???
   object O:
     val z: Any^ = ???
-  val baz3 = (i: Int) => [cap C, D <: C, E <: {C,x}] => () => [cap F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
+  val baz3 = (i: Int) => [cap C, cap D <: {C}, cap E <: {C,x}] => () => [cap F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
diff --git a/tests/pos-custom-args/captures/cap-paramlists.scala b/tests/pos-custom-args/captures/cap-paramlists.scala
@@ -7,17 +7,17 @@ def test =
   val y: Any^ = ???
   object O:
     val z: Any^ = ???
-  def foo[cap A >: y <: x,
-              B,
-              C <: {x},
-              D : Ctx,
-              E <: C,
-              F <: {C},
-              G <: {x, y},
-              H >: {x} <: {x,y} : Ctx]()[cap I <: {y, G, H},
-                                             J <: O.z,
-                                             K <: {x, O.z},
-                                             L <: {x, y, O.z},
-                                             M >: {x, y, O.z} <: C : Ctx,
-                                             N >: x <: x,
-                                             O >: O.z <: O.z] = ???
+  def foo[cap A >: {y} <: {x},
+          cap B,
+          cap C <: {x},
+          cap D : Ctx,
+          cap E <: {C},
+          cap F <: {C},
+          cap G <: {x, y},
+          cap H >: {x} <: {x,y} : Ctx, T, U]()[cap I <: {y, G, H},
+                                               cap J <: {O.z},
+                                               cap K <: {x, O.z},
+                                               cap L <: {x, y, O.z},
+                                               cap M >: {x, y, O.z} <: {C} : Ctx,
+                                               cap N >: {x} <: {x},
+                                               cap O >: {O.z} <: {O.z}] = ???
diff --git a/tests/pos-custom-args/captures/cap-paramlists2.scala b/tests/pos-custom-args/captures/cap-paramlists2.scala
@@ -1,6 +1,6 @@
 import language.experimental.captureChecking
 
 trait Bar:
-  cap C
+  cap type C
 
-def useFoo[cap D](x: Bar { cap C = D} ): Any^{x.C} = ???
+def useFoo[cap D](x: Bar { cap type C = {D} } ): Any^{x.C} = ???
diff --git a/tests/pos-custom-args/captures/cap-paramlists3.scala b/tests/pos-custom-args/captures/cap-paramlists3.scala
@@ -7,4 +7,4 @@ def test =
   val y: Any^ = ???
   object O:
     val z: Any^ = ???
-  val bar = [cap C, D <: C, E <: {C,x}, F >: {x,y} <: {C,E}] => (x: Int) => 1
+  val bar = [cap C, cap D <: {C}, cap E <: {C,x}, cap F >: {x,y} <: {C,E}] => (x: Int) => 1
diff --git a/tests/pos-custom-args/captures/cap-paramlists4.scala b/tests/pos-custom-args/captures/cap-paramlists4.scala
@@ -1,6 +1,6 @@
 import language.experimental.captureChecking
 
-trait Foo[cap U,V,W]:
-  cap C = caps.cap
-  cap D = {caps.cap}
-  cap E >: {V,W} <: U
+trait Foo[cap U, cap V, cap W]:
+  cap type C = {caps.cap}
+  cap type D = {caps.cap}
+  cap type E >: {V,W} <: {U}
diff --git a/tests/pos-custom-args/captures/cap-paramlists5.scala b/tests/pos-custom-args/captures/cap-paramlists5.scala
@@ -3,7 +3,7 @@ import language.experimental.namedTypeArguments
 
 def test2 =
   val x: Any^ = ???
-  def foo[cap A, B >: A](x: Int) = 1
-  foo[cap x, x](0)
-  foo[cap A = x, B = {x}](0)
-  foo[cap A = {x}](0)
+  def foo[cap A, cap B >: {A}, T](x: Int) = 1
+  foo[{x}, {x}, Int](0)
+ // foo[cap A = {x}, cap B = {x}](0)
+ // foo[cap A = {x}](0)
diff --git a/tests/pos-custom-args/captures/cap-paramlists6.scala b/tests/pos-custom-args/captures/cap-paramlists6.scala
@@ -7,4 +7,4 @@ def test =
   val y: Any^ = ???
   object O:
     val z: Any^ = ???
-  val baz  = () => [cap C, D <: C, E <: {C,x}, F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
+  val baz  = () => [cap C, cap D <: {C}, cap E <: {C,x}, cap F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
diff --git a/tests/pos-custom-args/captures/cap-paramlists7.scala b/tests/pos-custom-args/captures/cap-paramlists7.scala
@@ -7,4 +7,4 @@ def test =
   val y: Any^ = ???
   object O:
     val z: Any^ = ???
-  val baz2 = (i: Int) => [cap C, D <: C, E <: {C,x}, F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
+  val baz2 = (i: Int) => [cap C, cap D <: {C}, cap E <: {C,x}, cap F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
diff --git a/tests/pos-custom-args/captures/capset-members.scala b/tests/pos-custom-args/captures/capset-members.scala
@@ -8,18 +8,18 @@ def test =
   object O:
     val z: Any^ = ???
   trait CaptureSet:
-    cap A >: y <: x
-    cap B = x
-    cap C <: {x}
-    cap D : Ctx
-    cap E <: C
-    cap F <: {C}
-    cap G <: {x, y}
-    cap H >: {x} <: {x,y} : Ctx
-    cap I = {y, G, H}
-    cap J = {O.z}
-    cap K = {x, O.z}
-    cap L <: {x, y, O.z}
-    cap M >: {x, y, O.z} <: C
-    cap N >: x <: x
-    cap O >: O.z <: O.z
+    cap type A >: {y} <: {x}
+    cap type B = {x}
+    cap type C <: {x}
+    cap type D : Ctx
+    cap type E <: {C}
+    cap type F <: {C}
+    cap type G <: {x, y}
+    cap type H >: {x} <: {x,y} : Ctx
+    cap type I = {y, G, H}
+    cap type J = {O.z}
+    cap type K = {x, O.z}
+    cap type L <: {x, y, O.z}
+    cap type M >: {x, y, O.z} <: {C}
+    cap type N >: {x} <: {x}
+    cap type O >: {O.z} <: {O.z}

Original file line number	Diff line number	Diff line change
`@@ -234,6 +234,8 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {`
`234`	`234`
`235`	`235`	`case class Tracked()(implicit @constructorOnly src: SourceFile) extends Mod(Flags.Tracked)`
`236`	`236`
	`237`	`+ case class CaptureParam()(implicit @constructorOnly src: SourceFile) extends Mod(Flags.CaptureParam)`
	`238`	`+`
`237`	`239`	/** Used under pureFunctions to mark impure function types `A => B` in `FunctionWithMods` */
`238`	`240`	`case class Impure()(implicit @constructorOnly src: SourceFile) extends Mod(Flags.Impure)`
`239`	`241`	`}`