Add const reassign rule (#5388)

* Add const reassign rule * Update src/utils/logs.ts Co-authored-by: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com> * Update tests --------- Co-authored-by: Lukas Taegert-Atkinson <lukastaegert@users.noreply.github.com>
rollup · Feb 15, 2024 · d6fd383 · d6fd383
1 parent f74d0a9
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diff --git a/src/ast/nodes/AssignmentExpression.ts b/src/ast/nodes/AssignmentExpression.ts
@@ -1,5 +1,6 @@
 import type MagicString from 'magic-string';
 import { BLANK } from '../../utils/blank';
+import { logConstVariableReassignError } from '../../utils/logs';
 import {
 	findFirstOccurrenceOutsideComment,
 	findNonWhiteSpace,
@@ -79,6 +80,12 @@ export default class AssignmentExpression extends NodeBase {
 	}
 
 	initialise(): void {
+		if (this.left instanceof Identifier) {
+			const variable = this.scope.variables.get(this.left.name);
+			if (variable?.kind === 'const') {
+				this.scope.context.error(logConstVariableReassignError(), this.left.start);
+			}
+		}
 		this.left.setAssignedValue(this.right);
 	}
 

diff --git a/src/utils/logs.ts b/src/utils/logs.ts
@@ -82,6 +82,7 @@ const ADDON_ERROR = 'ADDON_ERROR',
 	CHUNK_INVALID = 'CHUNK_INVALID',
 	CIRCULAR_DEPENDENCY = 'CIRCULAR_DEPENDENCY',
 	CIRCULAR_REEXPORT = 'CIRCULAR_REEXPORT',
+	CONST_REASSIGN = 'CONST_REASSIGN',
 	CYCLIC_CROSS_CHUNK_REEXPORT = 'CYCLIC_CROSS_CHUNK_REEXPORT',
 	DEPRECATED_FEATURE = 'DEPRECATED_FEATURE',
 	DUPLICATE_ARGUMENT_NAME = 'DUPLICATE_ARGUMENT_NAME',
@@ -312,6 +313,13 @@ export function logDeprecation(
 	};
 }
 
+export function logConstVariableReassignError() {
+	return {
+		code: CONST_REASSIGN,
+		message: 'Cannot reassign a variable declared with `const`'
+	};
+}
+
 export function logDuplicateArgumentNameError(name: string): RollupLog {
 	return { code: DUPLICATE_ARGUMENT_NAME, message: `Duplicate argument name "${name}"` };
 }

diff --git a/test/function/samples/error-const-reassign/_config.js b/test/function/samples/error-const-reassign/_config.js
@@ -0,0 +1,21 @@
+const path = require('node:path');
+const MAIN_ID = path.resolve(__dirname, 'main.js');
+
+module.exports = defineTest({
+	description: 'Cannot reassign a variable declared with `const`',
+	error: {
+		code: 'CONST_REASSIGN',
+		frame: `
+			1: const foo = 1;\n2: foo = 2;\n   ^
+		`,
+		id: MAIN_ID,
+		loc: {
+			column: 0,
+			file: MAIN_ID,
+			line: 2
+		},
+		message: 'Cannot reassign a variable declared with `const`',
+		pos: 15,
+		watchFiles: [MAIN_ID]
+	}
+});
diff --git a/test/function/samples/error-const-reassign/main.js b/test/function/samples/error-const-reassign/main.js
@@ -0,0 +1,2 @@
+const foo = 1;
+foo = 2;