Rename caps.immutable to caps.freeze

Author: Linyxus

compiler/src/dotty/tools/dotc/cc/CheckCaptures.scala

@@ -800,8 +800,8 @@ class CheckCaptures extends Recheck, SymTransformer:
       capt.println(i"rechecking unsafeAssumePure of $arg with $pt: $argType")
       super.recheckFinish(argType, tree, pt)
 
-    /** Recheck `caps.immutable(...)` */
-    def applyImmutable(tree: Apply)(using Context): Type =
+    /** Recheck `caps.freeze(...)` */
+    def applyFreeze(tree: Apply)(using Context): Type =
       val arg :: Nil = tree.args: @unchecked
       def imm = new TypeMap:
         def apply(t: Type) = t match
@@ -816,7 +816,7 @@ class CheckCaptures extends Recheck, SymTransformer:
         case defn.ContextFunctionType(Nil, resType) => imm(resType)
 
     /** Recheck applications, with special handling of unsafeAssumePure,
-     *  unsafeDiscardUses, and immutable.
+     *  unsafeDiscardUses, and freeze.
      *  More work is done in `recheckApplication`, `recheckArg` and `instantiate` below.
      */
     override def recheckApply(tree: Apply, pt: Type)(using Context): Type =
@@ -826,8 +826,8 @@ class CheckCaptures extends Recheck, SymTransformer:
       else if meth == defn.Caps_unsafeDiscardUses then
         val arg :: Nil = tree.args: @unchecked
         withDiscardedUses(recheck(arg, pt))
-      else if meth == defn.Caps_immutable then
-        applyImmutable(tree)
+      else if meth == defn.Caps_freeze then
+        applyFreeze(tree)
       else
         val res = super.recheckApply(tree, pt)
         includeCallCaptures(meth, res, tree)

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1031,7 +1031,7 @@ class Definitions {
     @tu lazy val Caps_ContainsTrait: TypeSymbol = CapsModule.requiredType("Contains")
     @tu lazy val Caps_ContainsModule: Symbol = requiredModule("scala.caps.Contains")
     @tu lazy val Caps_containsImpl: TermSymbol = Caps_ContainsModule.requiredMethod("containsImpl")
-    @tu lazy val Caps_immutable: TermSymbol = CapsModule.requiredMethod("immutable")
+    @tu lazy val Caps_freeze: TermSymbol = CapsModule.requiredMethod("freeze")
 
   @tu lazy val PureClass: ClassSymbol = requiredClass("scala.caps.Pure")
 
@@ -2101,7 +2101,7 @@ class Definitions {
     RequiresCapabilityAnnot,
     captureRoot, Caps_CapSet, Caps_ContainsTrait, Caps_ContainsModule, Caps_ContainsModule.moduleClass,
     ConsumeAnnot, UseAnnot, ReserveAnnot,
-    CapsUnsafeModule, CapsUnsafeModule.moduleClass, Caps_immutable,
+    CapsUnsafeModule, CapsUnsafeModule.moduleClass, Caps_freeze,
     CapsInternalModule, CapsInternalModule.moduleClass,
     RetainsAnnot, RetainsCapAnnot, RetainsByNameAnnot)
 

library/src/scala/caps/package.scala

@@ -137,7 +137,7 @@ sealed trait Exists extends Capability
  *  result of pure operation `op`, turning them into immutable types.
  */
 @experimental
-def immutable[T](op: -> T): T = op
+def freeze[T](op: -> T): T = op
 
 @experimental
 object internal:

tests/neg-custom-args/captures/freeze.check

@@ -0,0 +1,22 @@
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/freeze.scala:13:17 ---------------------------------------
+13 |  val b = freeze(a) // error
+   |                 ^
+   |                 Found:    () ?->{a} Arr[String]^{a}
+   |                 Required: () ?-> <?>
+   |
+   |                 Note that capability a is not included in capture set {}.
+   |
+   | longer explanation available when compiling with `-explain`
+-- [E007] Type Mismatch Error: tests/neg-custom-args/captures/freeze.scala:22:4 ----------------------------------------
+21 |  freeze:
+22 |    mkExclusive() // error
+   |  ^
+   |  Capability cap outlives its scope: it leaks into outer capture set 's1 of method test3.
+   |  The leakage occurred when trying to match the following types:
+   |
+   |  Found:    EX^{cap}
+   |  Required: EX^'s1
+   |
+   |  where:    cap is a root capability associated with the result type of (): EX^
+   |
+   | longer explanation available when compiling with `-explain`

tests/neg-custom-args/captures/immutable.scala renamed to tests/neg-custom-args/captures/freeze.scala

@@ -10,14 +10,14 @@ def test2 =
   val a = Arr[String](2)
   a(0) = "1"
   a(1) = "2"
-  val b = immutable(a) // error
+  val b = freeze(a) // error
   b
 
 class EX
 
 def mkExclusive(): EX^ = ???
 
 def test3 =
-  immutable:
+  freeze:
     mkExclusive() // error
 

tests/neg-custom-args/captures/immutable.check

@@ -7,7 +7,7 @@ class Node(val payload: Int) extends Mutable:
 type INode = Node^{}
 
 def cycle(x: Int, y: Int): (INode, INode) =
-  immutable:
+  freeze:
     val a = Node(x)
     val b = Node(y)
     a.next = b

tests/pending/pos-custom-args/captures/immutable-cycle.scala renamed to tests/pending/pos-custom-args/captures/freeze-cycle.scala

@@ -8,14 +8,14 @@ class Arr[T: reflect.ClassTag](len: Int) extends Mutable:
 
 
 def test2 =
-  val a = immutable:
+  val a = freeze:
     val a = Arr[String](2)
     a(0) = "1"
     a(1) = "2"
     a
   val _: Arr[String]^{} = a
 
-  val a2 = immutable:
+  val a2 = freeze:
     val a = Arr[String](2)
     val b = Arr[String](2)
     a(0) = "1"