feat(typescript): allow override of forced noEmit and emitDeclarationOnly compiler options

packages/typescript/README.md

@@ -214,6 +214,15 @@ typescript({
 });
 ```
 
+### `noForceEmit`
+
+Type: `Boolean`<br>
+Default: `false`
+
+Earlier version of `@rollup/plugin-typescript` required that the `compilerOptions` `noEmit` and `emitDeclarationOnly` both false to guarantee that source code was fed into the next plugin/output. This is no longer true. This option disables the plugin forcing the values of those options and instead defers to the values set in `tsconfig.json`.
+
+`noForceEmit` can be very useful if you use with `@rollup/plugin-babel` and `@babel/preset-typescript`. Having `@rollup/plugin-typescript` only do typechecking / declarations with `"emitDeclarationOnly": true` while deferring to `@rollup/plugin-babel` for transpilation can dramatically reduce `rollup` build times for large projects.
+
 ### Typescript compiler options
 
 Some of Typescript's [CompilerOptions](https://www.typescriptlang.org/docs/handbook/compiler-options.html) affect how Rollup builds files.
@@ -238,6 +247,7 @@ These compiler options are ignored by Rollup:
 
 - `noEmitHelpers`, `importHelpers`: The `tslib` helper module always must be used.
 - `noEmit`, `emitDeclarationOnly`: Typescript needs to emit code for the plugin to work with.
+  - _Note: While this was true for early iterations of `@rollup/plugin-typescript`, it is no longer. To override this behavior, and defer to `tsconfig.json` for these options, see the [`noForceEmit`](#noForceEmit) option_
 - `noResolve`: Preventing Typescript from resolving code may break compilation
 
 ### Importing CommonJS

packages/typescript/src/index.ts

@@ -25,6 +25,7 @@ export default function typescript(options: RollupTypescriptOptions = {}): Plugi
     filterRoot,
     include,
     outputToFilesystem,
+    noForceEmit,
     transformers,
     tsconfig,
     tslib,
@@ -34,7 +35,7 @@ export default function typescript(options: RollupTypescriptOptions = {}): Plugi
   const emittedFiles = new Map<string, string>();
   const watchProgramHelper = new WatchProgramHelper();
 
-  const parsedOptions = parseTypescriptConfig(ts, tsconfig, compilerOptions);
+  const parsedOptions = parseTypescriptConfig(ts, tsconfig, compilerOptions, noForceEmit);
   const filter = createFilter(include || ['*.ts+(|x)', '**/*.ts+(|x)'], exclude, {
     resolve: filterRoot ?? parsedOptions.options.rootDir
   });

packages/typescript/src/options/interfaces.ts

@@ -13,13 +13,15 @@ export const DEFAULT_COMPILER_OPTIONS: PartialCompilerOptions = {
   skipLibCheck: true
 };
 
+export const OVERRIDABLE_EMIT_COMPILER_OPTIONS: Partial<CompilerOptions> = {
+  noEmit: false,
+  emitDeclarationOnly: false
+};
+
 export const FORCED_COMPILER_OPTIONS: Partial<CompilerOptions> = {
   // Always use tslib
   noEmitHelpers: true,
   importHelpers: true,
-  // Typescript needs to emit the code for us to work with
-  noEmit: false,
-  emitDeclarationOnly: false,
   // Preventing Typescript from resolving code may break compilation
   noResolve: false
 };

packages/typescript/src/options/plugin.ts

@@ -19,6 +19,7 @@ export const getPluginOptions = (options: RollupTypescriptOptions) => {
     exclude,
     include,
     filterRoot,
+    noForceEmit,
     transformers,
     tsconfig,
     tslib,
@@ -34,6 +35,7 @@ export const getPluginOptions = (options: RollupTypescriptOptions) => {
     include,
     exclude,
     filterRoot,
+    noForceEmit: noForceEmit || false,
     tsconfig,
     compilerOptions: { ...extra, ...compilerOptions } as PartialCompilerOptions,
     typescript: typescript || defaultTs,

packages/typescript/src/options/tsconfig.ts

@@ -21,6 +21,7 @@ import {
   DEFAULT_COMPILER_OPTIONS,
   EnumCompilerOptions,
   FORCED_COMPILER_OPTIONS,
+  OVERRIDABLE_EMIT_COMPILER_OPTIONS,
   PartialCompilerOptions
 } from './interfaces';
 import { normalizeCompilerOptions, makePathsAbsolute } from './normalize';
@@ -38,6 +39,10 @@ export interface TypeScriptConfig {
   compileOnSave?: boolean | undefined;
 }
 
+function makeForcedCompilerOptions(noForceEmit: boolean) {
+  return { ...FORCED_COMPILER_OPTIONS, ...(noForceEmit ? {} : OVERRIDABLE_EMIT_COMPILER_OPTIONS) };
+}
+
 /**
  * Finds the path to the tsconfig file relative to the current working directory.
  * @param relativePath Relative tsconfig path given by the user.
@@ -110,7 +115,8 @@ const configCache = new Map() as import('typescript').Map<ExtendedConfigCacheEnt
 export function parseTypescriptConfig(
   ts: typeof import('typescript'),
   tsconfig: RollupTypescriptOptions['tsconfig'],
-  compilerOptions: PartialCompilerOptions
+  compilerOptions: PartialCompilerOptions,
+  noForceEmit: boolean
 ): TypeScriptConfig {
   /* eslint-disable no-undefined */
   const cwd = process.cwd();
@@ -136,7 +142,7 @@ export function parseTypescriptConfig(
       },
       ts.sys,
       basePath,
-      { ...compilerOptions, ...FORCED_COMPILER_OPTIONS },
+      { ...compilerOptions, ...makeForcedCompilerOptions(noForceEmit) },
       tsConfigPath,
       undefined,
       undefined,
@@ -154,7 +160,7 @@ export function parseTypescriptConfig(
       },
       ts.sys,
       basePath,
-      FORCED_COMPILER_OPTIONS,
+      makeForcedCompilerOptions(noForceEmit),
       tsConfigPath,
       undefined,
       undefined,

packages/typescript/test/fixtures/incremental-single/tsconfig.tsbuildinfo

@@ -391,6 +391,11 @@
         "signature": "ef91066d2057cca50511e3af2d4aa54e07913a15f9cee1748f256139318eb413",
         "affectsGlobalScope": false
       },
+      "../../../../../node_modules/.pnpm/@babel+types@7.14.5/node_modules/@babel/types/lib/index.d.ts": {
+        "version": "a17ba25a194979a88bfd925e849d76b63f68c4160b69a99c5d723eac5ffddaf0",
+        "signature": "a17ba25a194979a88bfd925e849d76b63f68c4160b69a99c5d723eac5ffddaf0",
+        "affectsGlobalScope": false
+      },
       "../../../../../node_modules/.pnpm/@babel+parser@7.12.3/node_modules/@babel/parser/typings/babel-parser.d.ts": {
         "version": "8678956904af215fe917b2df07b6c54f876fa64eb1f8a158e4ff38404cef3ff4",
         "signature": "8678956904af215fe917b2df07b6c54f876fa64eb1f8a158e4ff38404cef3ff4",
@@ -744,15 +749,15 @@
       "configFilePath": "./tsconfig.json",
       "noEmitHelpers": true,
       "importHelpers": true,
+      "noResolve": false,
       "noEmit": false,
       "emitDeclarationOnly": false,
-      "noResolve": false,
       "sourceMap": true,
       "inlineSources": true
     },
     "referencedMap": {
       "../../../../../node_modules/.pnpm/@babel+parser@7.12.3/node_modules/@babel/parser/typings/babel-parser.d.ts": [
-        "../../../../../node_modules/.pnpm/@babel+types@7.12.1/node_modules/@babel/types/lib/index.d.ts"
+        "../../../../../node_modules/.pnpm/@babel+types@7.14.5/node_modules/@babel/types/lib/index.d.ts"
       ],
       "../../../../../node_modules/.pnpm/@types+babel__core@7.1.10/node_modules/@types/babel__core/index.d.ts": [
         "../../../../../node_modules/.pnpm/@babel+parser@7.12.3/node_modules/@babel/parser/typings/babel-parser.d.ts",
@@ -1154,7 +1159,7 @@
     },
     "exportedModulesMap": {
       "../../../../../node_modules/.pnpm/@babel+parser@7.12.3/node_modules/@babel/parser/typings/babel-parser.d.ts": [
-        "../../../../../node_modules/.pnpm/@babel+types@7.12.1/node_modules/@babel/types/lib/index.d.ts"
+        "../../../../../node_modules/.pnpm/@babel+types@7.14.5/node_modules/@babel/types/lib/index.d.ts"
       ],
       "../../../../../node_modules/.pnpm/@types+babel__core@7.1.10/node_modules/@types/babel__core/index.d.ts": [
         "../../../../../node_modules/.pnpm/@babel+parser@7.12.3/node_modules/@babel/parser/typings/babel-parser.d.ts",
@@ -1557,6 +1562,7 @@
     "semanticDiagnosticsPerFile": [
       "../../../../../node_modules/.pnpm/@babel+parser@7.12.3/node_modules/@babel/parser/typings/babel-parser.d.ts",
       "../../../../../node_modules/.pnpm/@babel+types@7.12.1/node_modules/@babel/types/lib/index.d.ts",
+      "../../../../../node_modules/.pnpm/@babel+types@7.14.5/node_modules/@babel/types/lib/index.d.ts",
       "../../../../../node_modules/.pnpm/@types+babel__core@7.1.10/node_modules/@types/babel__core/index.d.ts",
       "../../../../../node_modules/.pnpm/@types+babel__generator@7.6.2/node_modules/@types/babel__generator/index.d.ts",
       "../../../../../node_modules/.pnpm/@types+babel__template@7.0.3/node_modules/@types/babel__template/index.d.ts",

packages/typescript/test/fixtures/noForceEmit/emitDeclarationOnly/main.ts

@@ -0,0 +1,3 @@
+const answer = 42;
+
+export { answer };

packages/typescript/test/fixtures/noForceEmit/emitDeclarationOnly/tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "compilerOptions": {
+    "emitDeclarationOnly": true,
+    "declaration": true,
+    "outDir": "dist"
+  }
+}

packages/typescript/test/fixtures/noForceEmit/noEmit/main.ts

@@ -0,0 +1,3 @@
+const answer = 42;
+
+export { answer };

packages/typescript/test/fixtures/noForceEmit/noEmit/tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "compilerOptions": {
+    "declaration": true,
+    "noEmit": true,
+    "outDir": "dist"
+  }
+}

packages/typescript/test/test.js

@@ -1208,3 +1208,66 @@ test.serial('works when code is in src directory', async (t) => {
     ['index.js', 'index.d.ts']
   );
 });
+
+test.serial('noForceEmit option defers to tsconfig.json for emitDeclarationOnly', async (t) => {
+  const input = 'fixtures/noForceEmit/emitDeclarationOnly/main.ts';
+  const warnings = [];
+  const bundle = await rollup({
+    input,
+    plugins: [
+      typescript({
+        tsconfig: 'fixtures/noForceEmit/emitDeclarationOnly/tsconfig.json',
+        noForceEmit: true
+      })
+    ],
+    onwarn(warning) {
+      warnings.push(warning);
+    }
+  });
+  // generate a single output bundle, in which case, declaration files were not correctly emitted
+  const output = await getCode(
+    bundle,
+    { format: 'esm', file: 'fixtures/noForceEmit/emitDeclarationOnly/dist/main.js' },
+    true
+  );
+
+  t.deepEqual(
+    output.map((out) => out.fileName),
+    // original file is passed through, main.d.ts is emitted
+    ['main.js', 'main.d.ts']
+  );
+  t.is(warnings.length, 0);
+  // test that NO transpilation happened
+  const originalCode = fs.readFileSync(path.join(__dirname, input), 'utf8');
+  t.is(output[0].code, originalCode);
+});
+
+test.serial('noForceEmit option defers to tsconfig.json for noEmit', async (t) => {
+  const input = 'fixtures/noForceEmit/noEmit/main.ts';
+  const warnings = [];
+  const bundle = await rollup({
+    input,
+    plugins: [
+      typescript({ tsconfig: 'fixtures/noForceEmit/noEmit/tsconfig.json', noForceEmit: true })
+    ],
+    onwarn(warning) {
+      warnings.push(warning);
+    }
+  });
+  // generate a single output bundle, in which case, declaration files were not correctly emitted
+  const output = await getCode(
+    bundle,
+    { format: 'esm', file: 'fixtures/noForceEmit/noEmit/dist/main.js' },
+    true
+  );
+
+  t.deepEqual(
+    output.map((out) => out.fileName),
+    // no `main.d.ts`, main.js is passed through
+    ['main.js']
+  );
+  t.is(warnings.length, 0);
+  // test that NO transpilation happened
+  const originalCode = fs.readFileSync(path.join(__dirname, input), 'utf8');
+  t.is(output[0].code, originalCode);
+});

packages/typescript/types/index.d.ts

@@ -83,6 +83,10 @@ export interface RollupTypescriptPluginOptions {
    * Pass additional compiler options to the plugin.
    */
   compilerOptions?: PartialCompilerOptions;
+  /**
+   * Override force setting of `noEmit` and `emitDeclarationOnly` and use what is defined in `tsconfig.json`
+   */
+  noForceEmit?: boolean;
 }
 
 export interface FlexibleCompilerOptions extends CompilerOptions {