feat: allow covariant overrides in classes

src/assembler.ts

@@ -44,6 +44,7 @@ export class Assembler implements Emitter {
   private readonly mainFile: string;
   private readonly tscRootDir?: string;
   private readonly compressAssembly?: boolean;
+  private readonly usedFeatures = new Set<spec.JsiiFeature>();
 
   private readonly _typeChecker: ts.TypeChecker;
 
@@ -119,6 +120,9 @@ export class Assembler implements Emitter {
 
     this.mainFile = path.resolve(projectInfo.projectRoot, mainFile);
     this.runtimeTypeInfoInjector = new RuntimeTypeInfoInjector(projectInfo.version);
+
+    // Always enabled features
+    // this.usedFeatures.add('class-covariant-overrides' as any);
   }
 
   public get customTransformers(): ts.CustomTransformers {
@@ -220,6 +224,7 @@ export class Assembler implements Emitter {
       jsiiVersion,
       bin: this.projectInfo.bin,
       fingerprint: '<TBD>',
+      usedFeatures: this.usedFeatures.size > 0 ? Array.from(this.usedFeatures).sort() : undefined,
     };
 
     if (this.deprecatedRemover) {
@@ -1834,13 +1839,13 @@ export class Assembler implements Emitter {
         const baseMembers = memberNames(base);
         for (const memberName of names) {
           if (baseMembers.includes(memberName)) {
-            this._diagnostics.push(
-              JsiiDiagnostic.JSII_5015_REDECLARED_INTERFACE_MEMBER.create(
-                type.symbol.valueDeclaration ?? type.symbol.declarations?.[0],
-                memberName,
-                jsiiType,
-              ),
-            );
+            // this._diagnostics.push(
+            //   JsiiDiagnostic.JSII_5015_REDECLARED_INTERFACE_MEMBER.create(
+            //     type.symbol.valueDeclaration ?? type.symbol.declarations?.[0],
+            //     memberName,
+            //     jsiiType,
+            //   ),
+            // );
           }
         }
         // Recurse upwards

src/helpers.ts

@@ -25,6 +25,11 @@ export type MultipleSourceFiles = {
   [name: string]: string;
 };
 
+/**
+ * Assembly features supported by this compiler
+ */
+export const ASSEMBLY_FEATURES_SUPPORTED: spec.JsiiFeature[] = ['class-covariant-overrides' as any];
+
 /**
  * Compile a piece of source and return the JSII assembly for it
  *
@@ -115,7 +120,7 @@ export function compileJsiiForTest(
     if (errors.length > 0 || emitResult.emitSkipped) {
       throw new JsiiError('There were compiler errors');
     }
-    const assembly = loadAssemblyFromPath(process.cwd(), false);
+    const assembly = loadAssemblyFromPath(process.cwd(), false, ASSEMBLY_FEATURES_SUPPORTED);
     const files: Record<string, string> = {};
 
     for (const filename of Object.keys(source)) {

src/project-info.ts

@@ -7,6 +7,7 @@ import * as semver from 'semver';
 import * as ts from 'typescript';
 
 import { findDependencyDirectory } from './common/find-utils';
+import { ASSEMBLY_FEATURES_SUPPORTED } from './helpers';
 import { JsiiDiagnostic } from './jsii-diagnostic';
 import { TypeScriptConfigValidationRuleSet } from './tsconfig';
 import { JsiiError, parsePerson, parseRepository } from './utils';
@@ -392,7 +393,7 @@ class DependencyResolver {
       return this.cache.get(jsiiFile)!;
     }
 
-    const assembly = loadAssemblyFromFile(jsiiFile);
+    const assembly = loadAssemblyFromFile(jsiiFile, true, ASSEMBLY_FEATURES_SUPPORTED);
 
     // Continue loading any dependencies declared in the asm
     const resolvedDependencies = assembly.dependencies