feat: improve svelte/valid-compile to use svelte.config.js's onwarn (#796)

close #311

Author: ota-meshi

.changeset/onwarn.md

@@ -0,0 +1,5 @@
+---
+'eslint-plugin-svelte': minor
+---
+
+feat: improve `svelte/valid-compile` to use `svelte.config.js`'s `onwarn` from the parser.

docs/rules/valid-compile.md

@@ -37,6 +37,45 @@ This rule uses Svelte compiler to check the source code.
 
 Note that we exclude reports for some checks, such as `missing-declaration`, and `dynamic-slot-name`, which you can check with different ESLint rules.
 
+### Using `svelte.config.js`
+
+If you want to suppress messages using [`onwarn` like `vite-plugin-svelte`](https://github.com/sveltejs/vite-plugin-svelte/blob/main/docs/config.md#onwarn), Use `eslint.config.js` and specify the information in `svelte.config.js` in your parser configuration.
+
+```js
+import svelteConfig from './svelte.config.js';
+export default [
+  // ...
+  {
+    files: ['**/*.svelte', '*.svelte'],
+    languageOptions: {
+      parserOptions: {
+        svelteConfig: svelteConfig
+      }
+    }
+  }
+];
+```
+
+See also [User Guide > Specify `svelte.config.js`](../user-guide.md#specify-svelte-config-js)
+
+#### onwarn
+
+This rule can use [`onwarn` like `vite-plugin-svelte`](https://github.com/sveltejs/vite-plugin-svelte/blob/main/docs/config.md#onwarn).
+
+Example:
+
+```js
+// svelte.config.js
+export default {
+  onwarn: (warning, handler) => {
+    if (warning.code === 'a11y-distracting-elements') return;
+    if (warning.code === 'a11y_distracting_elements') return; // for Svelte v5
+
+    handler(warning);
+  }
+};
+```
+
 ## :wrench: Options
 
 ```json

packages/eslint-plugin-svelte/src/rules/valid-compile.ts

@@ -1,5 +1,5 @@
 import { createRule } from '../utils';
-import type { Warning } from '../shared/svelte-compile-warns';
+import type { SvelteCompileWarnings, Warning } from '../shared/svelte-compile-warns';
 import { getSvelteCompileWarnings } from '../shared/svelte-compile-warns';
 import { getSourceCode } from '../utils/compat';
 
@@ -23,9 +23,21 @@ export default createRule('valid-compile', {
 		type: 'problem'
 	},
 	create(context) {
-		if (!getSourceCode(context).parserServices.isSvelte) {
+		const sourceCode = getSourceCode(context);
+		if (!sourceCode.parserServices.isSvelte) {
 			return {};
 		}
+		const onwarn = sourceCode.parserServices.svelteParseContext?.svelteConfig?.onwarn;
+
+		const transform: (warning: Warning) => Warning | null = onwarn
+			? (warning) => {
+					if (!warning.code) return warning;
+					let result: Warning | null = null;
+					onwarn(warning, (reportWarn) => (result = reportWarn));
+					return result;
+				}
+			: (warning) => warning;
+
 		const ignoreWarnings = Boolean(context.options[0]?.ignoreWarnings);
 
 		const ignores = [
@@ -39,17 +51,21 @@ export default createRule('valid-compile', {
 		/**
 		 * report
 		 */
-		function report(warnings: Warning[]) {
+		function report({ warnings, kind }: SvelteCompileWarnings) {
 			for (const warn of warnings) {
 				if (warn.code && ignores.includes(warn.code)) {
 					continue;
 				}
+				const reportWarn = kind === 'warn' ? transform(warn) : warn;
+				if (!reportWarn) {
+					continue;
+				}
 				context.report({
 					loc: {
-						start: warn.start || warn.end || { line: 1, column: 0 },
-						end: warn.end || warn.start || { line: 1, column: 0 }
+						start: reportWarn.start || reportWarn.end || { line: 1, column: 0 },
+						end: reportWarn.end || reportWarn.start || { line: 1, column: 0 }
 					},
-					message: `${warn.message}${warn.code ? `(${warn.code})` : ''}`
+					message: `${reportWarn.message}${reportWarn.code ? `(${reportWarn.code})` : ''}`
 				});
 			}
 		}
@@ -60,7 +76,7 @@ export default createRule('valid-compile', {
 				if (ignoreWarnings && result.kind === 'warn') {
 					return;
 				}
-				report(result.warnings);
+				report(result);
 			}
 		};
 	}

packages/eslint-plugin-svelte/src/shared/svelte-compile-warns/index.ts

@@ -1,5 +1,4 @@
 import type { AST } from 'svelte-eslint-parser';
-import type {} from 'svelte'; // FIXME: Workaround to get type information for "svelte/compiler"
 import * as compiler from 'svelte/compiler';
 import type { SourceMapMappings } from '@jridgewell/sourcemap-codec';
 import { decode } from '@jridgewell/sourcemap-codec';
@@ -60,16 +59,25 @@ export type Loc = {
 	start?: {
 		line: number;
 		column: number;
+		character: number;
 	};
 	end?: {
 		line: number;
 		column: number;
+		character: number;
 	};
 };
-export type Warning = {
-	code?: string;
-	message: string;
-} & Loc;
+export type Warning = (
+	| {
+			code: string;
+			message: string;
+	  }
+	| {
+			code?: undefined;
+			message: string;
+	  }
+) &
+	Loc;
 
 /**
  * Get svelte compile warnings
@@ -228,51 +236,24 @@ function getSvelteCompileWarningsWithoutCache(context: RuleContext): SvelteCompi
 			}
 		}
 
-		public remapLocs(points: {
-			start?: {
-				line: number;
-				column: number;
-			};
-			end?: {
-				line: number;
-				column: number;
-			};
-		}): {
-			start?: {
-				line: number;
-				column: number;
-			};
-			end?: {
-				line: number;
-				column: number;
-			};
-		} {
+		public remapLocs(points: Loc): Loc {
 			const mapIndexes = this.mapIndexes;
 			const locs = (this.locs = this.locs ?? new LinesAndColumns(this.code));
-			let start:
-				| {
-						line: number;
-						column: number;
-				  }
-				| undefined = undefined;
-			let end:
-				| {
-						line: number;
-						column: number;
-				  }
-				| undefined = undefined;
+			let start: Loc['start'] | undefined = undefined;
+			let end: Loc['end'] | undefined = undefined;
 			if (points.start) {
 				const index = locs.getIndexFromLoc(points.start);
 				const remapped = remapIndex(index);
 				if (remapped) {
-					start = sourceCode.getLocFromIndex(remapped);
+					start = { ...sourceCode.getLocFromIndex(remapped), character: remapped };
 				}
 			}
 			if (points.end) {
 				const index = locs.getIndexFromLoc(points.end);
 				const remapped = remapIndex(index - 1 /* include index */);
 				if (remapped) {
-					end = sourceCode.getLocFromIndex(remapped + 1 /* restore */);
+					const character = remapped + 1; /* restore */
+					end = { ...sourceCode.getLocFromIndex(character), character };
 				}
 			}
 

packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/svelte-config-custom-warn/_config.js

@@ -0,0 +1,20 @@
+/**
+ * @typedef {import("svelte/compiler").Warning} Warning
+ */
+module.exports = {
+	languageOptions: {
+		parserOptions: {
+			svelteConfig: {
+				/**
+				 * @param {Warning} warning
+				 * @param {(warning: Warning) => void} handler
+				 * @returns {void}
+				 */
+				onwarn(warning, handler) {
+					// transform code
+					handler({ ...warning, code: 'foo' });
+				}
+			}
+		}
+	}
+};

packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/svelte-config-custom-warn/a11y-errors.yaml

@@ -0,0 +1,8 @@
+- message: '`<img>` element should have an alt attribute(foo)'
+  line: 5
+  column: 1
+  suggestions: null
+- message: Avoid using autofocus(foo)
+  line: 5
+  column: 12
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/svelte-config-custom-warn/a11y-input.svelte

@@ -0,0 +1,5 @@
+<script>
+	let src = 'tutorial/image.gif';
+</script>
+
+<img {src} autofocus />

packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/svelte-config-custom-warn/a11y-requirements.json

@@ -0,0 +1,3 @@
+{
+	"svelte": ">=5.0.0-0"
+}

packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/svelte-config-custom-warn/a11y-svelte4-errors.yaml

@@ -0,0 +1,8 @@
+- message: 'A11y: <img> element should have an alt attribute(foo)'
+  line: 5
+  column: 1
+  suggestions: null
+- message: 'A11y: Avoid using autofocus(foo)'
+  line: 5
+  column: 12
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/valid-compile/invalid/svelte-config-custom-warn/a11y-svelte4-input.svelte

@@ -0,0 +1,5 @@
+<script>
+	let src = 'tutorial/image.gif';
+</script>
+
+<img {src} autofocus />