Merge pull request #1015 from hylo-lang/custom-move

Implement IR support for custom conformances to 'Movable'

Sources/IR/Module.swift

@@ -237,12 +237,24 @@ public struct Module {
     functions[identity] = function
   }
 
+  /// Returns the identity of the IR function corresponding to `i`.
+  mutating func demandDeclaration(lowering i: Core.Conformance.Implementation) -> Function.ID {
+    switch i {
+    case .concrete(let d):
+      return demandDeclaration(lowering: d)!
+    case .synthetic(let d):
+      return demandDeclaration(lowering: d)
+    }
+  }
+
   /// Returns the identity of the IR function corresponding to `d`, or `nil` if `d` can't be
   /// lowered to an IR function.
   mutating func demandDeclaration(lowering d: AnyDeclID) -> Function.ID? {
     switch d.kind {
     case FunctionDecl.self:
       return demandDeclaration(lowering: FunctionDecl.ID(d)!)
+    case MethodImpl.self:
+      return demandDeclaration(lowering: MethodImpl.ID(d)!)
     case InitializerDecl.self:
       return demandDeclaration(lowering: InitializerDecl.ID(d)!)
     case SubscriptImpl.self:
@@ -393,31 +405,22 @@ public struct Module {
 
   /// Returns the identity of the IR function implementing the deinitializer defined in
   /// conformance `c`.
-  mutating func demandDeinitDeclaration(from c: Core.Conformance) -> Function.ID {
+  mutating func demandDeinitDeclaration(
+    from c: Core.Conformance
+  ) -> Function.ID {
     let d = program.ast.deinitRequirement()
-    switch c.implementations[d]! {
-    case .concrete(let s):
-      return demandDeclaration(lowering: FunctionDecl.ID(s)!)
-    case .synthetic(let s):
-      return demandDeclaration(lowering: s)
-    }
+    return demandDeclaration(lowering: c.implementations[d]!)
   }
 
-  /// Returns the identity of the IR function implementing the `k` variant move-operator defined in
-  /// conformance `c`.
+  /// Returns the identity of the IR function implementing the `k` variant move-operation defined
+  /// in conformance `c`.
   ///
   /// - Requires: `k` is either `.set` or `.inout`
   mutating func demandMoveOperatorDeclaration(
     _ k: AccessEffect, from c: Core.Conformance
   ) -> Function.ID {
     let d = program.ast.moveRequirement(k)
-    switch c.implementations[d]! {
-    case .concrete:
-      UNIMPLEMENTED()
-
-    case .synthetic(let s):
-      return demandDeclaration(lowering: s)
-    }
+    return demandDeclaration(lowering: c.implementations[d]!)
   }
 
   /// Returns the lowered declarations of `d`'s parameters.

Tests/EndToEndTests/TestCases/CustomMove.hylo

@@ -0,0 +1,32 @@
+//- compileAndRun expecting: success
+
+type A: Deinitializable {
+  var witness: Int
+  public var x: Int
+  public init(x: sink Int) {
+    &self.x = x
+    &self.witness = 0
+  }
+}
+
+conformance A: Movable {
+  public fun take_value(from source: sink Self) -> {self: Self, Void} {
+    set {
+      &self.x = source.x
+      &self.witness = 0
+    }
+    inout {
+      &self.x = source.x
+      &self.witness += 1
+    }
+  }
+}
+
+public fun main() {
+  var s = A(x: 1)
+  &s = A(x: 2)
+  &s = A(x: 2)
+
+  precondition(s.x == 2)
+  precondition(s.witness == 2)
+}