PoC: preventing infinite loops idea

Author: ota-meshi

packages/eslint-plugin-svelte/src/rules/no-dynamic-slot-name.ts

@@ -2,7 +2,7 @@ import type { AST } from 'svelte-eslint-parser';
 import type { TSESTree } from '@typescript-eslint/types';
 import { createRule } from '../utils/index.js';
 import {
-	findVariable,
+	findVariableSafe,
 	getAttributeValueQuoteAndRange,
 	getStringIfConstant
 } from '../utils/ast-utils.js';
@@ -72,23 +72,19 @@ export default createRule('no-dynamic-slot-name', {
 		}
 
 		/** Find data expression */
-		function findRootExpression(
-			node: TSESTree.Expression,
-			already = new Set<TSESTree.Identifier>()
-		): TSESTree.Expression {
-			if (node.type !== 'Identifier' || already.has(node)) {
+		function findRootExpression(node: TSESTree.Expression): TSESTree.Expression {
+			if (node.type !== 'Identifier') {
 				return node;
 			}
-			already.add(node);
-			const variable = findVariable(context, node);
+			const variable = findVariableSafe(findRootExpression, context, node);
 			if (!variable || variable.defs.length !== 1) {
 				return node;
 			}
 			const def = variable.defs[0];
 			if (def.type === 'Variable') {
 				if (def.parent.kind === 'const' && def.node.init) {
 					const init = def.node.init;
-					return findRootExpression(init, already);
+					return findRootExpression(init);
 				}
 			}
 			return node;

packages/eslint-plugin-svelte/src/rules/no-navigation-without-resolve.ts

@@ -1,7 +1,7 @@
 import type { TSESTree } from '@typescript-eslint/types';
 import { createRule } from '../utils/index.js';
 import { ReferenceTracker } from '@eslint-community/eslint-utils';
-import { findVariable } from '../utils/ast-utils.js';
+import { findVariableSafe } from '../utils/ast-utils.js';
 import type { RuleContext } from '../types.js';
 import type { AST } from 'svelte-eslint-parser';
 
@@ -126,7 +126,7 @@ function extractResolveReferences(
 		}
 	})) {
 		if (node.type === 'ImportSpecifier') {
-			const variable = findVariable(context, node.local);
+			const variable = findVariableSafe(extractResolveReferences, context, node.local);
 			if (variable === null) {
 				continue;
 			}
@@ -228,7 +228,7 @@ function isResolveCall(
 		return true;
 	}
 	if (node.type === 'Identifier') {
-		const variable = findVariable(context, node);
+		const variable = findVariableSafe(isResolveCall, context, node);
 		if (
 			variable !== null &&
 			variable.identifiers.length > 0 &&

packages/eslint-plugin-svelte/src/utils/ast-utils.ts

@@ -230,6 +230,43 @@ export function findVariable(context: RuleContext, node: TSESTree.Identifier): V
 	// Remove the $ and search for the variable again, as it may be a store access variable.
 	return eslintUtils.findVariable(initialScope, node.name.slice(1));
 }
+
+const findVariableSafeVisited = new WeakMap<
+	RuleContext,
+	// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type -- ignore
+	WeakMap<Function, Set<TSESTree.Identifier>>
+>();
+
+/**
+ * Find the variable of a given name safely, avoiding infinite recursion.
+ * This should be used when the caller function may be called recursively.
+ * @param caller The caller function. This is used to track recursion.
+ * @param context The rule context.
+ * @param node The identifier node to find.
+ */
+export function findVariableSafe(
+	// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type -- ignore
+	caller: Function,
+	context: RuleContext,
+	node: TSESTree.Identifier
+): Variable | null {
+	let visited = findVariableSafeVisited.get(context);
+	if (!visited) {
+		visited = new WeakMap();
+		findVariableSafeVisited.set(context, visited);
+	}
+	let visitedNodes = visited.get(caller);
+	if (!visitedNodes) {
+		visitedNodes = new Set();
+		visited.set(caller, visitedNodes);
+	}
+	if (visitedNodes.has(node)) {
+		return null;
+	}
+	visitedNodes.add(node);
+	return findVariable(context, node);
+}
+
 /**
  * Iterate the identifiers of a given pattern node.
  */

packages/eslint-plugin-svelte/src/utils/expression-affixes.ts

@@ -1,5 +1,5 @@
 import type { TSESTree } from '@typescript-eslint/types';
-import { findVariable } from './ast-utils.js';
+import { findVariableSafe } from './ast-utils.js';
 import type { RuleContext } from '../types.js';
 import type { AST } from 'svelte-eslint-parser';
 
@@ -36,7 +36,7 @@ function extractVariablePrefixVariable(
 	context: RuleContext,
 	expression: TSESTree.Identifier
 ): TSESTree.Identifier | null {
-	const variable = findVariable(context, expression);
+	const variable = findVariableSafe(extractVariablePrefixVariable, context, expression);
 	if (
 		variable === null ||
 		variable.identifiers.length !== 1 ||
@@ -111,7 +111,7 @@ function extractVariablePrefixLiteral(
 	context: RuleContext,
 	expression: TSESTree.Identifier
 ): string | null {
-	const variable = findVariable(context, expression);
+	const variable = findVariableSafe(extractVariablePrefixLiteral, context, expression);
 	if (
 		variable === null ||
 		variable.identifiers.length !== 1 ||
@@ -176,7 +176,7 @@ function extractVariableSuffixLiteral(
 	context: RuleContext,
 	expression: TSESTree.Identifier
 ): string | null {
-	const variable = findVariable(context, expression);
+	const variable = findVariableSafe(extractVariableSuffixLiteral, context, expression);
 	if (
 		variable === null ||
 		variable.identifiers.length !== 1 ||

packages/eslint-plugin-svelte/tests/fixtures/rules/consistent-selector-style/valid/type-id-class/recursive-loop01-input.svelte

@@ -0,0 +1,6 @@
+<script>
+	const a = derived;
+	const derived = a;
+</script>
+
+<a id={derived}>Click me!</a>

packages/eslint-plugin-svelte/tests/fixtures/rules/no-dynamic-slot-name/invalid/recursive-loop01-errors.yaml

@@ -0,0 +1,4 @@
+- message: '`<slot>` name cannot be dynamic.'
+  line: 6
+  column: 12
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/no-dynamic-slot-name/invalid/recursive-loop01-input.svelte

@@ -0,0 +1,6 @@
+<script>
+	const f = SLOT_NAME;
+	const SLOT_NAME = f;
+</script>
+
+<slot name={SLOT_NAME} />

packages/eslint-plugin-svelte/tests/fixtures/rules/no-dynamic-slot-name/invalid/recursive-loop01-output.svelte

@@ -0,0 +1,6 @@
+<script>
+	const f = SLOT_NAME;
+	const SLOT_NAME = f;
+</script>
+
+<slot name={SLOT_NAME} />

packages/eslint-plugin-svelte/tests/fixtures/rules/no-navigation-without-resolve/invalid/recursive-loop01-errors.yaml

@@ -0,0 +1,4 @@
+- message: Found a link with a url that isn't resolved.
+  line: 6
+  column: 9
+  suggestions: null

packages/eslint-plugin-svelte/tests/fixtures/rules/no-navigation-without-resolve/invalid/recursive-loop01-input.svelte

@@ -0,0 +1,6 @@
+<script>
+	const a = value;
+	const value = a;
+</script>
+
+<a href={value}>Click me!</a>