Enable 'no-empty' tslint rule (#19769)

* Enable 'no-empty' tslint rule

* Fix bug

Gulpfile.ts

@@ -74,7 +74,8 @@ const cmdLineOptions = minimist(process.argv.slice(2), {
     }
 });
 
-function exec(cmd: string, args: string[], complete: () => void = (() => { }), error: (e: any, status: number) => void = (() => { })) {
+const noop = () => {}; // tslint:disable-line no-empty
+function exec(cmd: string, args: string[], complete: () => void = noop, error: (e: any, status: number) => void = noop) {
     console.log(`${cmd} ${args.join(" ")}`);
     // TODO (weswig): Update child_process types to add windowsVerbatimArguments to the type definition
     const subshellFlag = isWin ? "/c" : "-c";

src/compiler/core.ts

@@ -1341,7 +1341,7 @@ namespace ts {
     }
 
     /** Does nothing. */
-    export function noop(): void { }
+    export function noop(_?: {} | null | undefined): void { } // tslint:disable-line no-empty
 
     /** Do nothing and return false */
     export function returnFalse(): false { return false; }
@@ -2659,8 +2659,7 @@ namespace ts {
         }
     }
 
-    function Signature() {
-    }
+    function Signature() {} // tslint:disable-line no-empty
 
     function Node(this: Node, kind: SyntaxKind, pos: number, end: number) {
         this.id = 0;
@@ -2931,7 +2930,7 @@ namespace ts {
         return (arg: T) => f(arg) && g(arg);
     }
 
-    export function assertTypeIsNever(_: never): void { }
+    export function assertTypeIsNever(_: never): void { } // tslint:disable-line no-empty
 
     export interface FileAndDirectoryExistence {
         fileExists: boolean;

src/compiler/performance.ts

@@ -10,9 +10,7 @@ namespace ts {
 namespace ts.performance {
     declare const onProfilerEvent: { (markName: string): void; profiler: boolean; };
 
-    const profilerEvent = typeof onProfilerEvent === "function" && onProfilerEvent.profiler === true
-            ? onProfilerEvent
-            : (_markName: string) => { };
+    const profilerEvent: (markName: string) => void = typeof onProfilerEvent === "function" && onProfilerEvent.profiler === true ? onProfilerEvent : noop;
 
     let enabled = false;
     let profilerStart = 0;

src/compiler/sys.ts

@@ -511,7 +511,7 @@ namespace ts {
                             return stat.size;
                         }
                     }
-                    catch (e) { }
+                    catch { /*ignore*/ }
                     return 0;
                 },
                 exit(exitCode?: number): void {
@@ -525,7 +525,7 @@ namespace ts {
                     try {
                         require("source-map-support").install();
                     }
-                    catch (e) {
+                    catch {
                         // Could not enable source maps.
                     }
                 },

src/harness/harness.ts

@@ -555,8 +555,7 @@ namespace Harness {
                 try {
                     fs.unlinkSync(path);
                 }
-                catch (e) {
-                }
+                catch { /*ignore*/ }
             }
 
             export function directoryExists(path: string): boolean {
@@ -615,7 +614,7 @@ namespace Harness {
 
             namespace Http {
                 function waitForXHR(xhr: XMLHttpRequest) {
-                    while (xhr.readyState !== 4) { }
+                    while (xhr.readyState !== 4) { } // tslint:disable-line no-empty
                     return { status: xhr.status, responseText: xhr.responseText };
                 }
 

src/harness/harnessLanguageService.ts

@@ -166,8 +166,7 @@ namespace Harness.LanguageService {
             throw new Error("No script with name '" + fileName + "'");
         }
 
-        public openFile(_fileName: string, _content?: string, _scriptKindName?: string): void {
-        }
+        public openFile(_fileName: string, _content?: string, _scriptKindName?: string): void { /*overridden*/ }
 
         /**
          * @param line 0 based index
@@ -237,9 +236,9 @@ namespace Harness.LanguageService {
         }
 
 
-        log(_: string): void { }
-        trace(_: string): void { }
-        error(_: string): void { }
+        log = ts.noop;
+        trace = ts.noop;
+        error = ts.noop;
     }
 
     export class NativeLanguageServiceAdapter implements LanguageServiceAdapter {
@@ -596,13 +595,8 @@ namespace Harness.LanguageService {
             super(cancellationToken, settings);
         }
 
-        onMessage(): void {
-
-        }
-
-        writeMessage(): void {
-
-        }
+        onMessage = ts.noop;
+        writeMessage = ts.noop;
 
         setClient(client: ts.server.SessionClient) {
             this.client = client;
@@ -628,13 +622,8 @@ namespace Harness.LanguageService {
             this.newLine = this.host.getNewLine();
         }
 
-        onMessage(): void {
-
-        }
-
-        writeMessage(_message: string): void {
-        }
-
+        onMessage = ts.noop;
+        writeMessage = ts.noop; // overridden
         write(message: string): void {
             this.writeMessage(message);
         }
@@ -648,8 +637,7 @@ namespace Harness.LanguageService {
             return snapshot && snapshot.getText(0, snapshot.getLength());
         }
 
-        writeFile(): void {
-        }
+        writeFile = ts.noop;
 
         resolvePath(path: string): string {
             return path;
@@ -668,8 +656,7 @@ namespace Harness.LanguageService {
             return "";
         }
 
-        exit(): void {
-        }
+        exit = ts.noop;
 
         createDirectory(_directoryName: string): void {
             return ts.notImplemented();
@@ -697,8 +684,7 @@ namespace Harness.LanguageService {
             return { close: ts.noop };
         }
 
-        close(): void {
-        }
+        close = ts.noop;
 
         info(message: string): void {
             this.host.log(message);

src/harness/projectsRunner.ts

@@ -396,7 +396,7 @@ class ProjectRunner extends RunnerBase {
             });
 
             // Dont allow config files since we are compiling existing source options
-            return compileProjectFiles(compilerResult.moduleKind, compilerResult.configFileSourceFiles, getInputFiles, getSourceFileText, writeFile, compilerResult.compilerOptions);
+            return compileProjectFiles(compilerResult.moduleKind, compilerResult.configFileSourceFiles, getInputFiles, getSourceFileText, /*writeFile*/ ts.noop, compilerResult.compilerOptions);
 
             function findOutputDtsFile(fileName: string) {
                 return ts.forEach(compilerResult.outputFiles, outputFile => outputFile.emittedFileName === fileName ? outputFile : undefined);
@@ -416,9 +416,6 @@ class ProjectRunner extends RunnerBase {
                 }
                 return undefined;
             }
-
-            function writeFile() {
-            }
         }
 
         function getErrorsBaseline(compilerResult: CompileProjectFilesResult) {

src/harness/runnerbase.ts

@@ -6,8 +6,6 @@ type CompilerTestKind = "conformance" | "compiler";
 type FourslashTestKind = "fourslash" | "fourslash-shims" | "fourslash-shims-pp" | "fourslash-server";
 
 abstract class RunnerBase {
-    constructor() { }
-
     // contains the tests to run
     public tests: string[] = [];
 

src/harness/unittests/extractTestHelpers.ts

@@ -126,7 +126,7 @@ namespace ts {
 
             const sourceFile = program.getSourceFile(path);
             const context: RefactorContext = {
-                cancellationToken: { throwIfCancellationRequested() { }, isCancellationRequested() { return false; } },
+                cancellationToken: { throwIfCancellationRequested: noop, isCancellationRequested: returnFalse },
                 newLineCharacter,
                 program,
                 file: sourceFile,
@@ -190,7 +190,7 @@ namespace ts {
             const program = projectService.inferredProjects[0].getLanguageService().getProgram();
             const sourceFile = program.getSourceFile(f.path);
             const context: RefactorContext = {
-                cancellationToken: { throwIfCancellationRequested() { }, isCancellationRequested() { return false; } },
+                cancellationToken: { throwIfCancellationRequested: noop, isCancellationRequested: returnFalse },
                 newLineCharacter,
                 program,
                 file: sourceFile,

src/harness/unittests/hostNewLineSupport.ts

@@ -5,10 +5,10 @@ namespace ts {
             function snapFor(path: string): IScriptSnapshot {
                 if (path === "lib.d.ts") {
                     return {
-                        dispose() {},
+                        dispose: noop,
                         getChangeRange() { return undefined; },
                         getLength() { return 0; },
-                        getText(_start, _end) {
+                        getText() {
                             return "";
                         }
                     };
@@ -16,7 +16,7 @@ namespace ts {
                 const result = forEach(files, f => f.unitName === path ? f : undefined);
                 if (result) {
                     return {
-                        dispose() {},
+                        dispose: noop,
                         getChangeRange() { return undefined; },
                         getLength() { return result.content.length; },
                         getText(start, end) {

src/harness/unittests/tsserverProjectSystem.ts

@@ -85,8 +85,7 @@ namespace ts.projectSystem {
             assert.equal(this.postExecActions.length, expectedCount, `Expected ${expectedCount} post install actions`);
         }
 
-        onProjectClosed() {
-        }
+        onProjectClosed = noop;
 
         attach(projectService: server.ProjectService) {
             this.projectService = projectService;
@@ -4717,7 +4716,7 @@ namespace ts.projectSystem {
             const host = createServerHost([f1, config]);
             const session = createSession(host, {
                 canUseEvents: true,
-                eventHandler: () => { },
+                eventHandler: noop,
                 cancellationToken
             });
             {
@@ -4854,7 +4853,7 @@ namespace ts.projectSystem {
             const host = createServerHost([f1, config]);
             const session = createSession(host, {
                 canUseEvents: true,
-                eventHandler: () => { },
+                eventHandler: noop,
                 cancellationToken,
                 throttleWaitMilliseconds: 0
             });

src/server/session.ts

@@ -1687,8 +1687,7 @@ namespace ts.server {
             return normalizePath(name);
         }
 
-        exit() {
-        }
+        exit() { /*overridden*/ }
 
         private notRequired(): HandlerResponse {
             return { responseRequired: false };

src/server/watchGuard/watchGuard.ts

@@ -14,6 +14,5 @@ try {
     const watcher = fs.watch(directoryName, { recursive: true }, () => ({}));
     watcher.close();
 }
-catch (_e) {
-}
+catch { /*ignore*/ }
 process.exit(0);

src/services/pathCompletions.ts

@@ -320,10 +320,9 @@ namespace ts.Completions.PathCompletions {
         else if (host.getDirectories) {
             let typeRoots: ReadonlyArray<string>;
             try {
-                // Wrap in try catch because getEffectiveTypeRoots touches the filesystem
                 typeRoots = getEffectiveTypeRoots(options, host);
             }
-            catch (e) {}
+            catch { /* Wrap in try catch because getEffectiveTypeRoots touches the filesystem */ }
 
             if (typeRoots) {
                 for (const root of typeRoots) {
@@ -484,7 +483,7 @@ namespace ts.Completions.PathCompletions {
         try {
             return directoryProbablyExists(path, host);
         }
-        catch (e) {}
+        catch { /*ignore*/ }
         return undefined;
     }
 
@@ -492,7 +491,7 @@ namespace ts.Completions.PathCompletions {
         try {
             return toApply && toApply.apply(host, args);
         }
-        catch (e) {}
+        catch { /*ignore*/ }
         return undefined;
     }
 }

tslint.json

@@ -86,7 +86,6 @@
         "no-conditional-assignment": false,
         "no-console": false,
         "no-debugger": false,
-        "no-empty": false,
         "no-empty-interface": false,
         "no-eval": false,
         "no-object-literal-type-assertion": false,