feat: add fixer for derived-has-same-inputs-outputs

.changeset/neat-dots-grin.md

@@ -0,0 +1,5 @@
+---
+'eslint-plugin-svelte': minor
+---
+
+Adds a suggestion to the `derived-has-same-inputs-outputs` rule which renames the outputs.

README.md

@@ -323,7 +323,7 @@ These rules relate to style guidelines, and are therefore quite subjective:
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [svelte/consistent-selector-style](https://sveltejs.github.io/eslint-plugin-svelte/rules/consistent-selector-style/) | enforce a consistent style for CSS selectors |  |
-| [svelte/derived-has-same-inputs-outputs](https://sveltejs.github.io/eslint-plugin-svelte/rules/derived-has-same-inputs-outputs/) | derived store should use same variable names between values and callback |  |
+| [svelte/derived-has-same-inputs-outputs](https://sveltejs.github.io/eslint-plugin-svelte/rules/derived-has-same-inputs-outputs/) | derived store should use same variable names between values and callback | :bulb: |
 | [svelte/first-attribute-linebreak](https://sveltejs.github.io/eslint-plugin-svelte/rules/first-attribute-linebreak/) | enforce the location of first attribute | :wrench: |
 | [svelte/html-closing-bracket-new-line](https://sveltejs.github.io/eslint-plugin-svelte/rules/html-closing-bracket-new-line/) | Require or disallow a line break before tag's closing brackets | :wrench: |
 | [svelte/html-closing-bracket-spacing](https://sveltejs.github.io/eslint-plugin-svelte/rules/html-closing-bracket-spacing/) | require or disallow a space before tag's closing brackets | :wrench: |

docs/rules.md

@@ -80,7 +80,7 @@ These rules relate to style guidelines, and are therefore quite subjective:
 | Rule ID                                                                                                  | Description                                                                        |          |
 | :------------------------------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------- | :------- |
 | [svelte/consistent-selector-style](./rules/consistent-selector-style.md)                                 | enforce a consistent style for CSS selectors                                       |          |
-| [svelte/derived-has-same-inputs-outputs](./rules/derived-has-same-inputs-outputs.md)                     | derived store should use same variable names between values and callback           |          |
+| [svelte/derived-has-same-inputs-outputs](./rules/derived-has-same-inputs-outputs.md)                     | derived store should use same variable names between values and callback           | :bulb:   |
 | [svelte/first-attribute-linebreak](./rules/first-attribute-linebreak.md)                                 | enforce the location of first attribute                                            | :wrench: |
 | [svelte/html-closing-bracket-new-line](./rules/html-closing-bracket-new-line.md)                         | Require or disallow a line break before tag's closing brackets                     | :wrench: |
 | [svelte/html-closing-bracket-spacing](./rules/html-closing-bracket-spacing.md)                           | require or disallow a space before tag's closing brackets                          | :wrench: |

docs/rules/derived-has-same-inputs-outputs.md

@@ -10,6 +10,8 @@ since: 'v2.8.0'
 
 > derived store should use same variable names between values and callback
 
+- :bulb: Some problems reported by this rule are manually fixable by editor [suggestions](https://eslint.org/docs/developer-guide/working-with-rules#providing-suggestions).
+
 ## :book: Rule Details
 
 This rule reports where variable names and callback function's argument names are different.

packages/eslint-plugin-svelte/src/rules/derived-has-same-inputs-outputs.ts

@@ -1,7 +1,56 @@
 import type { TSESTree } from '@typescript-eslint/types';
+import type { Variable } from '@typescript-eslint/scope-manager';
 import { createRule } from '../utils/index.js';
-import type { RuleContext } from '../types.js';
+import type { RuleContext, RuleFixer } from '../types.js';
 import { extractStoreReferences } from './reference-helpers/svelte-store.js';
+import { getScope } from '../utils/ast-utils.js';
+
+function findVariableForName(
+	context: RuleContext,
+	node: TSESTree.Node,
+	name: string,
+	expectedName: string
+): { hasConflict: boolean; variable: Variable | null } {
+	const scope = getScope(context, node);
+	let hasConflict = false;
+	let variable: Variable | null = null;
+
+	for (const ref of scope.references) {
+		if (ref.identifier.name === expectedName) {
+			hasConflict = true;
+			break;
+		}
+	}
+
+	if (!hasConflict) {
+		for (const v of scope.variables) {
+			if (hasConflict && variable) {
+				break;
+			}
+			if (v.name === expectedName) {
+				hasConflict = true;
+				continue;
+			}
+			if (v.name === name) {
+				variable = v;
+			}
+		}
+	}
+
+	return { hasConflict, variable };
+}
+
+function createFixer(node: TSESTree.Node, variable: Variable | null, name: string) {
+	return function* fix(fixer: RuleFixer) {
+		yield fixer.replaceText(node, name);
+
+		if (variable) {
+			for (const ref of variable.references) {
+				yield fixer.replaceText(ref.identifier, name);
+			}
+		}
+	};
+}
 
 export default createRule('derived-has-same-inputs-outputs', {
 	meta: {
@@ -11,9 +60,11 @@ export default createRule('derived-has-same-inputs-outputs', {
 			recommended: false,
 			conflictWithPrettier: false
 		},
+		hasSuggestions: true,
 		schema: [],
 		messages: {
-			unexpected: "The argument name should be '{{name}}'."
+			unexpected: "The argument name should be '{{name}}'.",
+			renameParam: 'Rename the parameter from {{oldName}} to {{newName}}.'
 		},
 		type: 'suggestion'
 	},
@@ -49,11 +100,27 @@ export default createRule('derived-has-same-inputs-outputs', {
 			if (fnParam.type !== 'Identifier') return;
 			const expectedName = `$${args.name}`;
 			if (expectedName !== fnParam.name) {
+				const { hasConflict, variable } = findVariableForName(
+					context,
+					fn.body,
+					fnParam.name,
+					expectedName
+				);
+
 				context.report({
 					node: fn,
 					loc: fnParam.loc,
 					messageId: 'unexpected',
-					data: { name: expectedName }
+					data: { name: expectedName },
+					suggest: hasConflict
+						? undefined
+						: [
+								{
+									messageId: 'renameParam',
+									data: { oldName: fnParam.name, newName: expectedName },
+									fix: createFixer(fnParam, variable, expectedName)
+								}
+							]
 				});
 			}
 		}
@@ -77,11 +144,27 @@ export default createRule('derived-has-same-inputs-outputs', {
 				if (element && element.type === 'Identifier' && argName) {
 					const expectedName = `$${argName}`;
 					if (expectedName !== element.name) {
+						const { hasConflict, variable } = findVariableForName(
+							context,
+							fn.body,
+							element.name,
+							expectedName
+						);
+
 						context.report({
 							node: fn,
 							loc: element.loc,
 							messageId: 'unexpected',
-							data: { name: expectedName }
+							data: { name: expectedName },
+							suggest: hasConflict
+								? undefined
+								: [
+										{
+											messageId: 'renameParam',
+											data: { oldName: element.name, newName: expectedName },
+											fix: createFixer(element, variable, expectedName)
+										}
+									]
 						});
 					}
 				}