fix: generate correct override stub for interface when implementation from base class

src/compiler.ts

@@ -612,7 +612,7 @@ export class Compiler extends DiagnosticEmitter {
       resolver.discoveredOverride = false;
       for (let _values = Set_values(overrideStubs), i = 0, k = _values.length; i < k; ++i) {
         let instance = unchecked(_values[i]);
-        let overrideInstances = resolver.resolveOverrides(instance);
+        let overrideInstances = resolver.resolveOverridesOrImplementations(instance);
         if (overrideInstances) {
           for (let i = 0, k = overrideInstances.length; i < k; ++i) {
             this.compileFunction(overrideInstances[i]);
@@ -6719,7 +6719,7 @@ export class Compiler extends DiagnosticEmitter {
         TypeRef.I32
       )
     );
-    let overrideInstances = this.resolver.resolveOverrides(instance);
+    let overrideInstances = this.resolver.resolveOverridesOrImplementations(instance);
     if (overrideInstances) {
       let mostRecentInheritanceMapping = new Map<Class, Class>();
       for (let i = 0, k = overrideInstances.length; i < k; ++i) {

src/program.ts

@@ -1440,7 +1440,7 @@ export class Program extends DiagnosticEmitter {
       }
       if (interfacePrototypes) {
         for (let j = 0, l = interfacePrototypes.length; j < l; ++j) {
-          this.processOverrides(thisPrototype, interfacePrototypes[j]);
+          this.processImplements(thisPrototype, interfacePrototypes[j]);
         }
       }
     }
@@ -1497,6 +1497,124 @@ export class Program extends DiagnosticEmitter {
     }
   }
 
+  private processImplements(thisPrototype: ClassPrototype, interfacePrototype: InterfacePrototype): void {
+    let interfaceInstanceMembers = interfacePrototype.instanceMembers;
+    if (interfaceInstanceMembers) {
+      for (let _values = Map_values(interfaceInstanceMembers), i = 0, k = _values.length; i < k; ++i) {
+        let interfaceMember = unchecked(_values[i]);
+        const implMember = this.searchImplementation(thisPrototype, interfaceMember.name);
+        if (!implMember) continue;
+        this.doProcessImplementation(thisPrototype, implMember, interfacePrototype, interfaceMember);
+      }
+    }
+    const interfaceBasePrototype = interfacePrototype.basePrototype;
+    if (interfaceBasePrototype) {
+      assert(interfaceBasePrototype.kind == ElementKind.InterfacePrototype);
+      this.processImplements(thisPrototype, <InterfacePrototype>interfaceBasePrototype);
+    }
+  }
+
+  private searchImplementation(thisPrototype: ClassPrototype, name: string): DeclaredElement | null {
+    let currentPrototype: ClassPrototype | null = thisPrototype;
+    while (currentPrototype) {
+      let currentInstanceMembers = currentPrototype.instanceMembers;
+      if (currentInstanceMembers && currentInstanceMembers.has(name)) {
+        return assert(currentInstanceMembers.get(name));
+      }
+      currentPrototype = currentPrototype.basePrototype;
+    }
+    return null;
+  }
+
+  private doProcessImplementation(
+    thisClass: ClassPrototype,
+    implMember: DeclaredElement,
+    interfacePrototype: InterfacePrototype,
+    interfaceMember: DeclaredElement
+  ): void {
+    if (implMember.kind == ElementKind.FunctionPrototype && interfaceMember.kind == ElementKind.FunctionPrototype) {
+      const implMethod = <FunctionPrototype>implMember;
+      const interfaceMethod = <FunctionPrototype>interfaceMember;
+      if (!implMethod.visibilityEquals(interfaceMethod)) {
+        this.errorRelated(
+          DiagnosticCode.Overload_signatures_must_all_be_public_private_or_protected,
+          implMethod.declaration.name.range,
+          interfaceMethod.declaration.name.range
+        );
+      }
+      interfaceMethod.addUnboundImplementations(thisClass, implMethod);
+      interfaceMethod.setOverrideFlag();
+    } else if (
+      implMember.kind == ElementKind.PropertyPrototype &&
+      interfaceMember.kind == ElementKind.PropertyPrototype
+    ) {
+      const implProperty = <PropertyPrototype>implMember;
+      const interfaceProperty = <PropertyPrototype>interfaceMember;
+      if (!implProperty.visibilityEquals(interfaceProperty)) {
+        this.errorRelated(
+          DiagnosticCode.Overload_signatures_must_all_be_public_private_or_protected,
+          implProperty.declaration.name.range,
+          interfaceProperty.declaration.name.range
+        );
+      }
+      if (interfaceProperty.parent.kind != ElementKind.InterfacePrototype) {
+        // Interface fields/properties can be impled by either, but other
+        // members must match to retain compatiblity with TS/JS.
+        const implIsField = implProperty.isField;
+        if (implIsField != interfaceProperty.isField) {
+          if (implIsField) {
+            // base is property
+            this.errorRelated(
+              DiagnosticCode._0_is_defined_as_an_accessor_in_class_1_but_is_overridden_here_in_2_as_an_instance_property,
+              implProperty.declaration.name.range,
+              interfaceProperty.declaration.name.range,
+              implProperty.name,
+              interfacePrototype.internalName,
+              thisClass.internalName
+            );
+          } else {
+            // this is property, base is field
+            this.errorRelated(
+              DiagnosticCode._0_is_defined_as_a_property_in_class_1_but_is_overridden_here_in_2_as_an_accessor,
+              implProperty.declaration.name.range,
+              interfaceProperty.declaration.name.range,
+              implProperty.name,
+              interfacePrototype.internalName,
+              thisClass.internalName
+            );
+          }
+          return;
+        } else if (implIsField) {
+          // base is also field
+          // Fields don't override other fields and can only be redeclared
+          return;
+        }
+      }
+      interfaceProperty.set(CommonFlags.Overridden);
+      const interfaceGetter = interfaceProperty.getterPrototype;
+      if (interfaceGetter) {
+        const implGetter = implProperty.getterPrototype;
+        if (implGetter) interfaceGetter.addUnboundImplementations(thisClass, implGetter);
+        interfaceGetter.setOverrideFlag();
+      }
+      const interfaceSetter = interfaceProperty.setterPrototype;
+      if (interfaceSetter && implProperty.setterPrototype) {
+        const implSetter = implProperty.setterPrototype;
+        if (implSetter) interfaceSetter.addUnboundImplementations(thisClass, implSetter);
+        interfaceSetter.setOverrideFlag();
+      }
+    } else {
+      this.errorRelated(
+        DiagnosticCode.Property_0_in_type_1_is_not_assignable_to_the_same_property_in_base_type_2,
+        implMember.declaration.name.range,
+        interfaceMember.declaration.name.range,
+        implMember.name,
+        thisClass.internalName,
+        interfacePrototype.internalName
+      );
+    }
+  }
+
   /** Processes overridden members by this class in a base class. */
   private processOverrides(
     thisPrototype: ClassPrototype,
@@ -1526,7 +1644,7 @@ export class Program extends DiagnosticEmitter {
           for (let i = 0, k = baseInterfacePrototypes.length; i < k; ++i) {
             let baseInterfacePrototype = baseInterfacePrototypes[i];
             if (baseInterfacePrototype != basePrototype) {
-              this.processOverrides(thisPrototype, baseInterfacePrototype);
+              this.processImplements(thisPrototype, baseInterfacePrototype);
             }
           }
         }
@@ -3667,6 +3785,8 @@ export class FunctionPrototype extends DeclaredElement {
   instances: Map<string,Function> | null = null;
   /** Methods overriding this one, if any. These are unbound. */
   unboundOverrides: Set<FunctionPrototype> | null = null;
+  /** Methods implement this one, if any. These are unbound. */
+  unboundImplementations: Map<ClassPrototype, FunctionPrototype> | null = null;
 
   /** Clones of this prototype that are bound to specific classes. */
   private boundPrototypes: Map<Class,FunctionPrototype> | null = null;
@@ -3731,6 +3851,7 @@ export class FunctionPrototype extends DeclaredElement {
     bound.flags = this.flags;
     bound.operatorKind = this.operatorKind;
     bound.unboundOverrides = this.unboundOverrides;
+    bound.unboundImplementations = this.unboundImplementations;
     // NOTE: this.instances holds instances per bound class / unbound
     boundPrototypes.set(classInstance, bound);
     return bound;
@@ -3750,6 +3871,24 @@ export class FunctionPrototype extends DeclaredElement {
     else assert(!instances.has(instanceKey));
     instances.set(instanceKey, instance);
   }
+
+
+  setOverrideFlag(): void {
+    this.set(CommonFlags.Overridden);
+    let instances = this.instances;
+    if (instances) {
+      for (let _values = Map_values(instances), a = 0, b = _values.length; a < b; ++a) {
+        let instance = _values[a];
+        instance.set(CommonFlags.Overridden);
+      }
+    }
+  }
+
+  addUnboundImplementations(thisClass: ClassPrototype, implementMember: DeclaredElement): void {
+    let unboundImplementations = this.unboundImplementations;
+    if (!unboundImplementations) this.unboundImplementations = unboundImplementations = new Map();
+    unboundImplementations.set(thisClass, <FunctionPrototype>implementMember);
+  }
 }
 
 /** A resolved function. */

src/resolver.ts

@@ -3014,12 +3014,21 @@ export class Resolver extends DiagnosticEmitter {
     );
   }
 
+  /** Resolves reachable overrides or implementations of the given instance method. */
+  resolveOverridesOrImplementations(instance: Function): Function[] | null {
+    if (instance.parent.kind == ElementKind.Interface) {
+      return this.resolveImplementations(instance);
+    } else {
+      assert(instance.parent.kind == ElementKind.Class);
+      return this.resolveOverrides(instance);
+    }
+  }
+
+
   /** Resolves reachable overrides of the given instance method. */
-  resolveOverrides(instance: Function): Function[] | null {
+  private resolveOverrides(instance: Function): Function[] | null {
     let overridePrototypes = instance.prototype.unboundOverrides;
     if (!overridePrototypes) return null;
-
-    let parentClassInstance = assert(instance.getBoundClassOrInterface());
     let overrides = new Set<Function>();
 
     // A method's `overrides` property contains its unbound override prototypes
@@ -3034,35 +3043,72 @@ export class Resolver extends DiagnosticEmitter {
       classInstances = (<ClassPrototype>unboundOverrideParent).instances;
       if (!classInstances) continue;
       for (let _values = Map_values(classInstances), j = 0, l = _values.length; j < l; ++j) {
-        let classInstance = _values[j];
-        // Check if the parent class is a subtype of instance's class
-        if (!classInstance.isAssignableTo(parentClassInstance)) continue;
-        let overrideInstance: Function | null = null;
-        if (instance.isAny(CommonFlags.Get | CommonFlags.Set)) {
-          let propertyName = instance.declaration.name.text;
-          let boundPropertyPrototype = assert(classInstance.getMember(propertyName));
-          assert(boundPropertyPrototype.kind == ElementKind.PropertyPrototype);
-          let boundPropertyInstance = this.resolveProperty(<PropertyPrototype>boundPropertyPrototype);
-          if (!boundPropertyInstance) continue;
-          if (instance.is(CommonFlags.Get)) {
-            overrideInstance = boundPropertyInstance.getterInstance;
-          } else {
-            assert(instance.is(CommonFlags.Set));
-            overrideInstance = boundPropertyInstance.setterInstance;
-          }
-        } else {
-          let boundPrototype = classInstance.getMember(unboundOverridePrototype.name);
-          if (boundPrototype) { // might have errored earlier and wasn't added
-            assert(boundPrototype.kind == ElementKind.FunctionPrototype);
-            overrideInstance = this.resolveFunction(<FunctionPrototype>boundPrototype, instance.typeArguments);
-          }
-        }
+        const overrideInstance = this.doResolveOverrideOrImplementation(instance, _values[j], unboundOverridePrototype);
         if (overrideInstance) overrides.add(overrideInstance);
       }
     }
     return Set_values(overrides);
   }
 
+  private resolveImplementations(instance: Function): Function[] | null {
+    let unboundImplementations = instance.prototype.unboundImplementations;
+    if (!unboundImplementations) return null;
+    let implementations = new Set<Function>();
+    for (
+      let _keys = Map_keys(unboundImplementations),
+          _values = Map_values(unboundImplementations),
+          i = 0,
+          k = _keys.length;
+      i < k;
+      ++i
+    ) {
+      /** in {@link classPrototype}, we implement {@link instance} by {@link unboundImplPrototype} */
+      const classPrototype = _keys[i];
+      const unboundImplPrototype = _values[i];
+      assert(!unboundImplPrototype.isBound);
+
+      let classInstances = classPrototype.instances;
+      if (!classInstances) continue;
+      for (let _values = Map_values(classInstances), j = 0, l = _values.length; j < l; ++j) {
+        const implInstance = this.doResolveOverrideOrImplementation(instance, _values[j], unboundImplPrototype);
+        if (implInstance) implementations.add(implInstance);
+      }
+    }
+    return Set_values(implementations);
+  }
+
+  private doResolveOverrideOrImplementation(
+    instance: Function,
+    classInstance: Class,
+    unboundPrototype: FunctionPrototype
+  ): Function | null {
+    const parentClassInstance = assert(instance.getBoundClassOrInterface());
+    // Check if the parent class is a subtype of instance's class
+    if (!classInstance.isAssignableTo(parentClassInstance)) return null;
+    let ret: Function | null = null;
+    if (instance.isAny(CommonFlags.Get | CommonFlags.Set)) {
+      let propertyName = instance.identifierNode.text;
+      let boundPropertyPrototype = assert(classInstance.getMember(propertyName));
+      assert(boundPropertyPrototype.kind == ElementKind.PropertyPrototype);
+      let boundPropertyInstance = this.resolveProperty(<PropertyPrototype>boundPropertyPrototype);
+      if (!boundPropertyInstance) return null;
+      if (instance.is(CommonFlags.Get)) {
+        ret = boundPropertyInstance.getterInstance;
+      } else {
+        assert(instance.is(CommonFlags.Set));
+        ret = boundPropertyInstance.setterInstance;
+      }
+    } else {
+      let boundPrototype = classInstance.getMember(unboundPrototype.name);
+      if (boundPrototype) {
+        // might have errored earlier and wasn't added
+        assert(boundPrototype.kind == ElementKind.FunctionPrototype);
+        ret = this.resolveFunction(<FunctionPrototype>boundPrototype, instance.typeArguments);
+      }
+    }
+    return ret;
+  }
+
   /** Currently resolving classes. */
   private resolveClassPending: Set<Class> = new Set();
 

tests/compiler/class-implements.debug.wat

@@ -2331,9 +2331,6 @@
   local.get $this
   i32.load offset=4
  )
- (func $class-implements/K#foo (param $this i32) (result i32)
-  unreachable
- )
  (func $class-implements/G#foo (param $this i32) (result i32)
   i32.const 1
   return
@@ -2415,40 +2412,31 @@
  (func $class-implements/J#foo@override (param $0 i32) (result i32)
   (local $1 i32)
   block $default
-   block $case3
-    block $case2
-     block $case1
-      block $case0
-       local.get $0
-       i32.const 8
-       i32.sub
-       i32.load
-       local.set $1
-       local.get $1
-       i32.const 13
-       i32.eq
-       br_if $case0
-       local.get $1
-       i32.const 11
-       i32.eq
-       br_if $case1
-       local.get $1
-       i32.const 8
-       i32.eq
-       br_if $case2
-       local.get $1
-       i32.const 10
-       i32.eq
-       br_if $case2
-       local.get $1
-       i32.const 12
-       i32.eq
-       br_if $case3
-       br $default
-      end
+   block $case2
+    block $case1
+     block $case0
       local.get $0
-      call $class-implements/K#foo
-      return
+      i32.const 8
+      i32.sub
+      i32.load
+      local.set $1
+      local.get $1
+      i32.const 11
+      i32.eq
+      br_if $case0
+      local.get $1
+      i32.const 8
+      i32.eq
+      br_if $case1
+      local.get $1
+      i32.const 10
+      i32.eq
+      br_if $case1
+      local.get $1
+      i32.const 12
+      i32.eq
+      br_if $case2
+      br $default
      end
      local.get $0
      call $class-implements/F#foo