Enable --isolatedDeclarations on TS codebase

eslint.config.mjs

@@ -118,6 +118,7 @@ export default tseslint.config(
             "@typescript-eslint/ban-ts-comment": "off",
             "@typescript-eslint/class-literal-property-style": "off",
             "@typescript-eslint/consistent-indexed-object-style": "off",
+            "@typescript-eslint/consistent-generic-constructors": "off",
             "@typescript-eslint/no-duplicate-enum-values": "off",
             "@typescript-eslint/no-empty-function": "off",
             "@typescript-eslint/no-namespace": "off",

scripts/processDiagnosticMessages.mjs

@@ -92,6 +92,7 @@ function buildInfoFileOutput(messageTable, inputFilePathRel) {
         "    return { code, category, key, message, reportsUnnecessary, elidedInCompatabilityPyramid, reportsDeprecated };",
         "}",
         "",
+        "/* eslint-disable @typescript-eslint/no-unnecessary-type-assertion*/", // type assertions are needed for isolatedDeclarations
         "/** @internal */",
         "export const Diagnostics = {",
     ];
@@ -101,7 +102,7 @@ function buildInfoFileOutput(messageTable, inputFilePathRel) {
         const argElidedInCompatabilityPyramid = elidedInCompatabilityPyramid ? `${!reportsUnnecessary ? ", /*reportsUnnecessary*/ undefined" : ""}, /*elidedInCompatabilityPyramid*/ ${elidedInCompatabilityPyramid}` : "";
         const argReportsDeprecated = reportsDeprecated ? `${!argElidedInCompatabilityPyramid ? ", /*reportsUnnecessary*/ undefined, /*elidedInCompatabilityPyramid*/ undefined" : ""}, /*reportsDeprecated*/ ${reportsDeprecated}` : "";
 
-        result.push(`    ${propName}: diag(${code}, DiagnosticCategory.${category}, "${createKey(propName, code)}", ${JSON.stringify(name)}${argReportsUnnecessary}${argElidedInCompatabilityPyramid}${argReportsDeprecated}),`);
+        result.push(`    ${propName}: diag(${code}, DiagnosticCategory.${category}, "${createKey(propName, code)}", ${JSON.stringify(name)}${argReportsUnnecessary}${argElidedInCompatabilityPyramid}${argReportsDeprecated}) as DiagnosticMessage,`);
     });
 
     result.push("};");

src/compiler/binder.ts

@@ -509,7 +509,7 @@ export function createFlowNode(flags: FlowFlags, node: unknown, antecedent: Flow
 const binder = /* @__PURE__ */ createBinder();
 
 /** @internal */
-export function bindSourceFile(file: SourceFile, options: CompilerOptions) {
+export function bindSourceFile(file: SourceFile, options: CompilerOptions): void {
     performance.mark("beforeBind");
     binder(file, options);
     performance.mark("afterBind");

src/compiler/builder.ts

@@ -8,6 +8,7 @@ import {
     BuilderProgramHost,
     BuilderState,
     BuildInfo,
+    BuildInfoFileVersionMap,
     CancellationToken,
     CommandLineOption,
     compareStringsCaseSensitive,
@@ -277,7 +278,7 @@ function toBuilderProgramStateWithDefinedProgram(state: ReusableBuilderProgramSt
  *
  * @internal
  */
-export function getBuilderFileEmit(options: CompilerOptions) {
+export function getBuilderFileEmit(options: CompilerOptions): BuilderFileEmit {
     let result = BuilderFileEmit.Js;
     if (options.sourceMap) result = result | BuilderFileEmit.JsMap;
     if (options.inlineSourceMap) result = result | BuilderFileEmit.JsInlineMap;
@@ -733,7 +734,7 @@ export function getPendingEmitKindWithSeen(
     seenOldOptionsOrEmitKind: CompilerOptions | BuilderFileEmit | undefined,
     emitOnlyDtsFiles: boolean | undefined,
     isForDtsErrors: boolean,
-) {
+): BuilderFileEmit {
     let pendingKind = getPendingEmitKind(optionsOrEmitKind, seenOldOptionsOrEmitKind);
     if (emitOnlyDtsFiles) pendingKind = pendingKind & BuilderFileEmit.AllDts;
     if (isForDtsErrors) pendingKind = pendingKind & BuilderFileEmit.DtsErrors;
@@ -1623,7 +1624,7 @@ export function computeSignatureWithDiagnostics(
     text: string,
     host: HostForComputeHash,
     data: WriteFileCallbackData | undefined,
-) {
+): string {
     text = getTextHandlingSourceMapForSignature(text, data);
     let sourceFileDirectory: string | undefined;
     if (data?.diagnostics?.length) {
@@ -2395,7 +2396,7 @@ export function getBuildInfoFileVersionMap(
     program: IncrementalBuildInfo,
     buildInfoPath: string,
     host: Pick<ReadBuildProgramHost, "useCaseSensitiveFileNames" | "getCurrentDirectory">,
-) {
+): BuildInfoFileVersionMap {
     const buildInfoDirectory = getDirectoryPath(getNormalizedAbsolutePath(buildInfoPath, host.getCurrentDirectory()));
     const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames());
     const fileInfos = new Map<Path, string>();
@@ -2440,7 +2441,7 @@ export function getNonIncrementalBuildInfoRoots(
     buildInfo: BuildInfo,
     buildInfoPath: string,
     host: Pick<ReadBuildProgramHost, "useCaseSensitiveFileNames" | "getCurrentDirectory">,
-) {
+): Path[] | undefined {
     if (!isNonIncrementalBuildInfo(buildInfo)) return undefined;
     const buildInfoDirectory = getDirectoryPath(getNormalizedAbsolutePath(buildInfoPath, host.getCurrentDirectory()));
     const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames());

src/compiler/builderState.ts

@@ -292,11 +292,11 @@ export namespace BuilderState {
     /**
      * Returns true if oldState is reusable, that is the emitKind = module/non module has not changed
      */
-    export function canReuseOldState(newReferencedMap: ReadonlyManyToManyPathMap | undefined, oldState: BuilderState | undefined) {
+    export function canReuseOldState(newReferencedMap: ReadonlyManyToManyPathMap | undefined, oldState: BuilderState | undefined): boolean | undefined {
         return oldState && !oldState.referencedMap === !newReferencedMap;
     }
 
-    export function createReferencedMap(options: CompilerOptions) {
+    export function createReferencedMap(options: CompilerOptions): ManyToManyPathMap | undefined {
         return options.module !== ModuleKind.None && !options.outFile ?
             createManyToManyPathMap() :
             undefined;
@@ -346,7 +346,7 @@ export namespace BuilderState {
     /**
      * Releases needed properties
      */
-    export function releaseCache(state: BuilderState) {
+    export function releaseCache(state: BuilderState): void {
         state.allFilesExcludingDefaultLibraryFile = undefined;
         state.allFileNames = undefined;
     }
@@ -391,7 +391,7 @@ export namespace BuilderState {
         return (state.referencedMap ? getFilesAffectedByUpdatedShapeWhenModuleEmit : getFilesAffectedByUpdatedShapeWhenNonModuleEmit)(state, programOfThisState, sourceFile, cancellationToken, host);
     }
 
-    export function updateSignatureOfFile(state: BuilderState, signature: string | undefined, path: Path) {
+    export function updateSignatureOfFile(state: BuilderState, signature: string | undefined, path: Path): void {
         state.fileInfos.get(path)!.signature = signature;
         (state.hasCalledUpdateShapeSignature ||= new Set()).add(path);
     }
@@ -402,7 +402,7 @@ export namespace BuilderState {
         cancellationToken: CancellationToken | undefined,
         host: HostForComputeHash,
         onNewSignature: (signature: string, sourceFiles: readonly SourceFile[]) => void,
-    ) {
+    ): void {
         programOfThisState.emit(
             sourceFile,
             (fileName, text, _writeByteOrderMark, _onError, sourceFiles, data) => {
@@ -434,8 +434,8 @@ export namespace BuilderState {
         sourceFile: SourceFile,
         cancellationToken: CancellationToken | undefined,
         host: HostForComputeHash,
-        useFileVersionAsSignature = state.useFileVersionAsSignature,
-    ) {
+        useFileVersionAsSignature: boolean | undefined = state.useFileVersionAsSignature,
+    ): boolean {
         // If we have cached the result for this file, that means hence forth we should assume file shape is uptodate
         if (state.hasCalledUpdateShapeSignature?.has(sourceFile.resolvedPath)) return false;
 
@@ -507,7 +507,7 @@ export namespace BuilderState {
     /**
      * Gets the files referenced by the the file path
      */
-    export function getReferencedByPaths(state: Readonly<BuilderState>, referencedFilePath: Path) {
+    export function getReferencedByPaths(state: Readonly<BuilderState>, referencedFilePath: Path): Path[] {
         const keys = state.referencedMap!.getKeys(referencedFilePath);
         return keys ? arrayFrom(keys.keys()) : [];
     }

src/compiler/checker.ts

@@ -1450,7 +1450,7 @@ export function getSymbolId(symbol: Symbol): SymbolId {
 }
 
 /** @internal */
-export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums: boolean) {
+export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums: boolean): boolean {
     const moduleState = getModuleInstanceState(node);
     return moduleState === ModuleInstanceState.Instantiated ||
         (preserveConstEnums && moduleState === ModuleInstanceState.ConstEnumOnly);
@@ -52709,7 +52709,7 @@ function getIterationTypesKeyFromIterationTypeKind(typeKind: IterationTypeKind)
 }
 
 /** @internal */
-export function signatureHasRestParameter(s: Signature) {
+export function signatureHasRestParameter(s: Signature): boolean {
     return !!(s.flags & SignatureFlags.HasRestParameter);
 }
 

src/compiler/commandLineParser.ts

@@ -138,7 +138,7 @@ const jsxOptionMap = new Map(Object.entries({
 }));
 
 /** @internal */
-export const inverseJsxOptionMap = new Map(mapIterator(jsxOptionMap.entries(), ([key, value]: [string, JsxEmit]) => ["" + value, key] as const));
+export const inverseJsxOptionMap: Map<string, string> = new Map(mapIterator(jsxOptionMap.entries(), ([key, value]: [string, JsxEmit]) => ["" + value, key] as const));
 
 // NOTE: The order here is important to default lib ordering as entries will have the same
 //       order in the generated program (see `getDefaultLibPriority` in program.ts). This
@@ -248,15 +248,15 @@ const libEntries: [string, string][] = [
  *
  * @internal
  */
-export const libs = libEntries.map(entry => entry[0]);
+export const libs: string[] = libEntries.map(entry => entry[0]);
 
 /**
  * A map of lib names to lib files. This map is used both for parsing the "lib" command line
  * option as well as for resolving lib reference directives.
  *
  * @internal
  */
-export const libMap = new Map(libEntries);
+export const libMap: Map<string, string> = new Map(libEntries);
 
 // Watch related options
 
@@ -1800,7 +1800,7 @@ function createDiagnosticForInvalidCustomType(opt: CommandLineOptionOfCustomType
 }
 
 /** @internal */
-export function parseCustomTypeOption(opt: CommandLineOptionOfCustomType, value: string | undefined, errors: Diagnostic[]) {
+export function parseCustomTypeOption(opt: CommandLineOptionOfCustomType, value: string | undefined, errors: Diagnostic[]): string | number | undefined {
     return convertJsonOptionOfCustomType(opt, (value ?? "").trim(), errors);
 }
 
@@ -1835,6 +1835,14 @@ export interface OptionsBase {
     [option: string]: CompilerOptionsValue | TsConfigSourceFile | undefined;
 }
 
+/** @internal */
+export interface BaseParsedCommandLine {
+    options: OptionsBase;
+    watchOptions: WatchOptions | undefined;
+    fileNames: string[];
+    errors: Diagnostic[];
+}
+
 /** @internal */
 export interface ParseCommandLineWorkerDiagnostics extends DidYouMeanOptionsDiagnostics {
     getOptionsNameMap: () => OptionsNameMap;
@@ -1875,7 +1883,7 @@ export function parseCommandLineWorker(
     diagnostics: ParseCommandLineWorkerDiagnostics,
     commandLine: readonly string[],
     readFile?: (path: string) => string | undefined,
-) {
+): BaseParsedCommandLine {
     const options = {} as OptionsBase;
     let watchOptions: WatchOptions | undefined;
     const fileNames: string[] = [];
@@ -2602,11 +2610,11 @@ export function convertToTSConfig(configParseResult: ParsedCommandLine, configFi
     const providedKeys = new Set(optionMap.keys());
     const impliedCompilerOptions: Record<string, CompilerOptionsValue> = {};
     for (const option in computedOptions) {
-        if (!providedKeys.has(option) && some(computedOptions[option as keyof typeof computedOptions].dependencies, dep => providedKeys.has(dep))) {
-            const implied = computedOptions[option as keyof typeof computedOptions].computeValue(configParseResult.options);
-            const defaultValue = computedOptions[option as keyof typeof computedOptions].computeValue({});
+        if (!providedKeys.has(option) && some(computedOptions[option].dependencies, dep => providedKeys.has(dep))) {
+            const implied = computedOptions[option].computeValue(configParseResult.options);
+            const defaultValue = computedOptions[option].computeValue({});
             if (implied !== defaultValue) {
-                impliedCompilerOptions[option] = computedOptions[option as keyof typeof computedOptions].computeValue(configParseResult.options);
+                impliedCompilerOptions[option] = computedOptions[option].computeValue(configParseResult.options);
             }
         }
     }
@@ -2866,7 +2874,7 @@ export function generateTSConfig(options: CompilerOptions, fileNames: readonly s
 }
 
 /** @internal */
-export function convertToOptionsWithAbsolutePaths(options: CompilerOptions, toAbsolutePath: (path: string) => string) {
+export function convertToOptionsWithAbsolutePaths(options: CompilerOptions, toAbsolutePath: (path: string) => string): CompilerOptions {
     const result: CompilerOptions = {};
     const optionsNameMap = getOptionsNameMap().optionsNameMap;
 
@@ -2927,7 +2935,7 @@ export function parseJsonSourceFileConfigFileContent(sourceFile: TsConfigSourceF
 }
 
 /** @internal */
-export function setConfigFileInOptions(options: CompilerOptions, configFile: TsConfigSourceFile | undefined) {
+export function setConfigFileInOptions(options: CompilerOptions, configFile: TsConfigSourceFile | undefined): void {
     if (configFile) {
         Object.defineProperty(options, "configFile", { enumerable: false, writable: false, value: configFile });
     }
@@ -3243,12 +3251,12 @@ function shouldReportNoInputFiles(fileNames: string[], canJsonReportNoInutFiles:
 }
 
 /** @internal */
-export function canJsonReportNoInputFiles(raw: any) {
+export function canJsonReportNoInputFiles(raw: any): boolean {
     return !hasProperty(raw, "files") && !hasProperty(raw, "references");
 }
 
 /** @internal */
-export function updateErrorForNoInputFiles(fileNames: string[], configFileName: string, configFileSpecs: ConfigFileSpecs, configParseDiagnostics: Diagnostic[], canJsonReportNoInutFiles: boolean) {
+export function updateErrorForNoInputFiles(fileNames: string[], configFileName: string, configFileSpecs: ConfigFileSpecs, configParseDiagnostics: Diagnostic[], canJsonReportNoInutFiles: boolean): boolean {
     const existingErrors = configParseDiagnostics.length;
     if (shouldReportNoInputFiles(fileNames, canJsonReportNoInutFiles)) {
         configParseDiagnostics.push(getErrorForNoInputFiles(configFileSpecs, configFileName));
@@ -3943,7 +3951,7 @@ export function matchesExclude(
     excludeSpecs: readonly string[] | undefined,
     useCaseSensitiveFileNames: boolean,
     currentDirectory: string,
-) {
+): boolean {
     return matchesExcludeWorker(
         pathToCheck,
         filter(excludeSpecs, spec => !invalidDotDotAfterRecursiveWildcard(spec)),