System format optional setters (#3592)

* system optional setters

* update option list

* fixup tests

* Update changelog

* Improve documentation and adapt for normalized options

Co-authored-by: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>

CHANGELOG.md

@@ -1,5 +1,22 @@
 # rollup changelog
 
+## 2.11.0
+*2020-05-27*
+
+### Features
+* Provide a normalized set of options with proper default values to `buildStart` and `renderStart` (#3597)
+* Do not count adding properties to the prototype of an unused class as a side-effect (#3598)
+
+### Bug Fixes
+* Do not fail when using a `/*#__PURE__*/` annotation inside a class field (#3599)
+* Allow using `--watch` and `--treeshake` together with sub-options such as `--watch.clearScreen` on the command line (#3597)
+
+### Pull Requests
+* [#3597](https://github.com/rollup/rollup/pull/3597): Provide normalized options (@lukastaegert)
+* [#3598](https://github.com/rollup/rollup/pull/3598): Treeshake prototype modifications in classes (@lukastaegert)
+* [#3599](https://github.com/rollup/rollup/pull/3599): Retain pure annotations in class fields (@lukastaegert)
+* [#3601](https://github.com/rollup/rollup/pull/3601): Fix white-space in docs (@tu4mo)
+
 ## 2.10.9
 *2020-05-24*
 

cli/help.md

@@ -54,6 +54,7 @@ Basic options:
 --no-stdin                  do not read "-" from stdin
 --no-strict                 Don't emit `"use strict";` in the generated modules
 --strictDeprecations        Throw errors for deprecated features
+--systemNullSetters         Replace empty SystemJS setters with `null`
 --no-treeshake              Disable tree-shaking optimisations
 --no-treeshake.annotations  Ignore pure call annotations
 --no-treeshake.moduleSideEffects Assume modules have no side-effects

docs/01-command-line-reference.md

@@ -93,7 +93,8 @@ export default { // can be an array (for multiple inputs)
     namespaceToStringTag,
     noConflict,
     preferConst,
-    strict
+    strict,
+    systemNullSetters
   },
 
   watch: {
@@ -310,6 +311,7 @@ Many options have command line equivalents. In those cases, any arguments passed
 --no-stdin                  do not read "-" from stdin
 --no-strict                 Don't emit `"use strict";` in the generated modules
 --strictDeprecations        Throw errors for deprecated features
+--systemNullSetters         Replace empty SystemJS setters with `null`
 --no-treeshake              Disable tree-shaking optimisations
 --no-treeshake.annotations  Ignore pure call annotations
 --no-treeshake.moduleSideEffects Assume modules have no side-effects

docs/02-javascript-api.md

@@ -148,7 +148,8 @@ const outputOptions = {
   namespaceToStringTag,
   noConflict,
   preferConst,
-  strict
+  strict,
+  systemNullSetters
 };
 ```
 

docs/999-big-list-of-options.md

@@ -1045,6 +1045,13 @@ Default: `true`
 
 Whether to include the 'use strict' pragma at the top of generated non-ES bundles. Strictly speaking, ES modules are *always* in strict mode, so you shouldn't disable this without good reason.
 
+#### output.systemNullSetters
+Type: `boolean`<br>
+CLI: `--systemNullSetters`/`--no-systemNullSetters`<br>
+Default: `false`
+
+When outputting the `system` module format, this will replace empty setter functions with `null` as an output simplification. This is *only supported in SystemJS 6.3.3 and above*.
+
 #### preserveSymlinks
 Type: `boolean`<br>
 CLI: `--preserveSymlinks`<br>

src/finalisers/system.ts

@@ -193,6 +193,8 @@ export default function system(
 						.map(s =>
 							s
 								? `function${_}(module)${_}{${n}${t}${t}${t}${s}${n}${t}${t}}`
+								: options.systemNullSetters
+								? `null`
 								: `function${_}()${_}{}`
 						)
 						.join(`,${_}`)}],`

src/rollup/types.d.ts

@@ -567,6 +567,7 @@ export interface OutputOptions {
 	sourcemapFile?: string;
 	sourcemapPathTransform?: (sourcePath: string) => string;
 	strict?: boolean;
+	systemNullSetters?: boolean;
 }
 
 export interface NormalizedOutputOptions {
@@ -608,6 +609,7 @@ export interface NormalizedOutputOptions {
 	sourcemapFile: string | undefined;
 	sourcemapPathTransform: ((sourcePath: string) => string) | undefined;
 	strict: boolean;
+	systemNullSetters: boolean;
 }
 
 export type WarningHandlerWithDefault = (

src/utils/options/mergeOptions.ts

@@ -217,7 +217,8 @@ function mergeOutputOptions(
 		sourcemapExcludeSources: getOption('sourcemapExcludeSources'),
 		sourcemapFile: getOption('sourcemapFile'),
 		sourcemapPathTransform: getOption('sourcemapPathTransform'),
-		strict: getOption('strict')
+		strict: getOption('strict'),
+		systemNullSetters: getOption('systemNullSetters')
 	};
 
 	warnUnknownOptions(config, Object.keys(outputOptions), 'output options', warn);

src/utils/options/normalizeOutputOptions.ts

@@ -59,7 +59,8 @@ export function normalizeOutputOptions(
 		sourcemapPathTransform: config.sourcemapPathTransform as
 			| ((sourcePath: string) => string)
 			| undefined,
-		strict: (config.strict as boolean | undefined) ?? true
+		strict: (config.strict as boolean | undefined) ?? true,
+		systemNullSetters: (config.systemNullSetters as boolean | undefined) || false
 	};
 
 	warnUnknownOptions(config, Object.keys(outputOptions), 'output options', inputOptions.onwarn);

test/form/samples/unused-import/_config.js

@@ -3,7 +3,8 @@ module.exports = {
 	options: {
 		external: ['external'],
 		output: {
-			globals: { external: 'external' }
+			globals: { external: 'external' },
+			systemNullSetters: true
 		}
 	}
 };

test/form/samples/unused-import/_expected/system.js

@@ -1,7 +1,7 @@
 System.register(['external'], function () {
 	'use strict';
 	return {
-		setters: [function () {}],
+		setters: [null],
 		execute: function () {
 
 

test/hooks/index.js

@@ -65,7 +65,8 @@ describe('hooks', () => {
 								preferConst: false,
 								sourcemap: false,
 								sourcemapExcludeSources: false,
-								strict: true
+								strict: true,
+								systemNullSetters: false
 							});
 							assert.strictEqual(options.banner(), 'new banner');
 						},