Support cap params in type refinements

Author: bracevac

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -225,6 +225,7 @@ object Parsers {
     def isErasedKw = isErased && in.isSoftModifierInParamModifierPosition
     // Are we seeing a `cap` soft keyword for declaring a capture-set member or at the beginning a capture-variable parameter list?
     def isCapKw = Feature.ccEnabled && isIdent(nme.cap)
+    // This will typically be used at the beginning of a type parameter list to check if it is a capture-variable parameter list:
     def isCapKwNext = Feature.ccEnabled && in.lookahead.isIdent(nme.cap)
     def isSimpleLiteral =
       simpleLiteralTokens.contains(in.token)
@@ -1916,7 +1917,7 @@ object Parsers {
         refinedTypeRest(atSpan(startOffset(t)) {
           RefinedTypeTree(rejectWildcardType(t), refinement(indentOK = true))
         })
-      else if Feature.ccEnabled && in.isIdent(nme.UPARROW) && isCaptureUpArrow then
+      else if Feature.ccEnabled && in.isIdent(nme.UPARROW) && isCaptureUpArrow then // TODO remove
         atSpan(t.span.start):
           in.nextToken()
           if in.token == LBRACE
@@ -4858,7 +4859,7 @@ object Parsers {
             fail(em"this kind of definition cannot be a refinement")
 
       while
-        val dclFound = isDclIntro
+        val dclFound = isDclIntro || isCapKw // TODO grammar doc
         if dclFound then
           stats ++= checkLegal(defOrDcl(in.offset, Modifiers()))
         var what = "declaration"

tests/pending/cap-paramlists8.scala

@@ -0,0 +1,10 @@
+import language.experimental.captureChecking
+
+trait Ctx[T]
+
+def test =
+  val x: Any^ = ???
+  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

tests/pos-custom-args/captures/cap-paramlists.scala

@@ -1,5 +1,4 @@
 import language.experimental.captureChecking
-import language.experimental.namedTypeArguments
 
 trait Ctx[T]
 
@@ -8,7 +7,6 @@ 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
   def foo[cap A >: y <: x,
               B,
               C <: {x},
@@ -22,20 +20,4 @@ def test =
                                              L <: {x, y, O.z},
                                              M >: {x, y, O.z} <: C : Ctx,
                                              N >: x <: x,
-                                             O >: O.z <: O.z] = ???
-  val baz  = () => [cap C, D <: C, E <: {C,x}, F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
-  val baz2 = (i: Int) => [cap C, D <: C, E <: {C,x}, F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
-  val baz3 = (i: Int) => [cap C, D <: C, E <: {C,x}] => () => [cap F >: {x,y} <: {C,E} : Ctx] => (x: Int) => 1
-
-
-trait Foo[cap U,V,W]:
-  cap C = caps.cap
-  cap D = {caps.cap}
-  cap E >: {V,W} <: U
-
-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)
+                                             O >: O.z <: O.z] = ???

tests/pos-custom-args/captures/cap-paramlists2.scala

@@ -0,0 +1,6 @@
+import language.experimental.captureChecking
+
+trait Bar:
+  cap C
+
+def useFoo[cap D](x: Bar { cap C = D} ): Any^{x.C} = ???

tests/pos-custom-args/captures/cap-paramlists3.scala

@@ -0,0 +1,10 @@
+import language.experimental.captureChecking
+
+trait Ctx[T]
+
+def test =
+  val x: Any^ = ???
+  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

tests/pos-custom-args/captures/cap-paramlists4.scala

@@ -0,0 +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

tests/pos-custom-args/captures/cap-paramlists5.scala

@@ -0,0 +1,9 @@
+import language.experimental.captureChecking
+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)

tests/pos-custom-args/captures/cap-paramlists6.scala

@@ -0,0 +1,10 @@
+import language.experimental.captureChecking
+
+trait Ctx[T]
+
+def test =
+  val x: Any^ = ???
+  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

tests/pos-custom-args/captures/cap-paramlists7.scala

@@ -0,0 +1,10 @@
+import language.experimental.captureChecking
+
+trait Ctx[T]
+
+def test =
+  val x: Any^ = ???
+  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