fix(prefer-array-to-sorted): skip non-array iterable spreads (#134)

* fix(prefer-array-to-sorted): bail on non-array iterable spread without type info

Avoid unsafe untyped autofixes for spread-copy sorts whose source is known not to be an array. These rewrites can otherwise turn Set/Map/iterator sources into invalid `.toSorted()` calls.

Bail on known collection constructors, local identifiers initialized from those constructors, iterator-returning `.entries()`/`.keys()`/`.values()` calls, and TS syntax-only iterable annotations when type services are unavailable. Keep `Object.entries()` and known array sources fixable.

Verified with the focused rule test, lint, build, and a consumer probe across representative checked-out projects.

* chore: drop casts

* chore: remove redundant check

Variable IDs are the same as their declarator's name, so no need
checking it again.

---------

Co-authored-by: James Garbutt <43081j@users.noreply.github.com>

Author: webpro

src/rules/prefer-array-to-sorted.test.ts

@@ -25,6 +25,14 @@ const ruleTester = new RuleTester({
     sourceType: 'module'
   }
 });
+const tsSyntaxRuleTester = new TSRuleTester({
+  languageOptions: {
+    parserOptions: {
+      ecmaVersion: 2022,
+      sourceType: 'module'
+    }
+  }
+});
 
 ruleTester.run(
   'prefer-array-to-sorted (untyped)',
@@ -40,7 +48,17 @@ ruleTester.run(
 
       // slice with different arguments
       'arr.slice(1).sort();',
-      'arr.slice(0, 5).sort();'
+      'arr.slice(0, 5).sort();',
+
+      'const sorted = [...new Set([1, 2, 3])].sort();',
+      'const sorted = [...new Set(arr)].sort();',
+      'const sorted = [...new Map()].sort();',
+      'const foundVersions = new Set(); const sorted = [...foundVersions].sort();',
+      'let foundVersions = new Set(); const sorted = [...foundVersions].sort();',
+      'const entries = new Map(); const sorted = [...entries].sort();',
+      'const sorted = [...items.entries()].sort();',
+      'const sorted = [...items.keys()].sort();',
+      'const sorted = [...items.values()].sort();'
     ],
 
     invalid: [
@@ -174,6 +192,12 @@ ruleTester.run(
           }
         ]
       },
+      {
+        code: 'const sorted = [...Object.entries(counts)].sort(([a], [b]) => a.localeCompare(b));',
+        output:
+          'const sorted = Object.entries(counts).toSorted(([a], [b]) => a.localeCompare(b));',
+        errors: [{messageId: 'preferToSorted'}]
+      },
 
       // Multiple arguments (edge case - sort() typically takes 0 or 1 arg)
       {
@@ -244,6 +268,26 @@ ruleTester.run(
   }
 );
 
+tsSyntaxRuleTester.run(
+  'prefer-array-to-sorted (typescript syntax)',
+  preferArrayToSorted,
+  {
+    valid: [
+      'function sortItems<T>(items: Iterable<T>) { return [...items].sort(); }',
+      'function sortItems(items: Map<string, number>) { return [...items.entries()].sort(); }',
+      'const items: Set<string> = new Set(); const sorted = [...items].sort();',
+      'let items: Iterable<string>; const sorted = [...items].sort();'
+    ],
+    invalid: [
+      {
+        code: 'const items: string[] = []; const sorted = [...items].sort();',
+        output: 'const items: string[] = []; const sorted = items.toSorted();',
+        errors: [{messageId: 'preferToSorted'}]
+      }
+    ]
+  }
+);
+
 typedRuleTester.run('prefer-array-to-sorted (typed)', preferArrayToSorted, {
   valid: [
     // Set spread - Set doesn't have toSorted()

src/rules/prefer-array-to-sorted.ts

@@ -9,6 +9,116 @@ import {isArrayType} from '../utils/typescript.js';
 
 type MessageIds = 'preferToSorted';
 
+const NON_ARRAY_COPY_SOURCE_CTORS = new Set(['Set', 'Map']);
+const NON_ARRAY_COPY_SOURCE_TYPES = new Set([
+  'Iterable',
+  'IterableIterator',
+  'Iterator',
+  'Map',
+  'ReadonlyMap',
+  'ReadonlySet',
+  'Set',
+  'URLSearchParams'
+]);
+const ITERATOR_RETURNING_METHODS = new Set(['entries', 'keys', 'values']);
+
+function getTypeReferenceName(node: TSESTree.Node): string | null {
+  if (node.type !== 'TSTypeReference') {
+    return null;
+  }
+
+  const {typeName} = node;
+  if (typeName.type === 'Identifier') {
+    return typeName.name;
+  }
+  if (typeName.type === 'TSQualifiedName') {
+    return typeName.right.name;
+  }
+  return null;
+}
+
+function hasKnownNonArrayTypeAnnotation(node: TSESTree.BindingName): boolean {
+  const typeAnnotation = node.typeAnnotation;
+  if (typeAnnotation === undefined) {
+    return false;
+  }
+
+  const annotation = typeAnnotation.typeAnnotation;
+  if (annotation.type === 'TSUnionType') {
+    return annotation.types.some((typeNode) => hasKnownNonArrayType(typeNode));
+  }
+  return hasKnownNonArrayType(annotation);
+}
+
+function hasKnownNonArrayType(node: TSESTree.Node): boolean {
+  const typeName = getTypeReferenceName(node);
+  return typeName !== null && NON_ARRAY_COPY_SOURCE_TYPES.has(typeName);
+}
+
+function isIteratorReturningCall(node: TSESTree.Node): boolean {
+  return (
+    node.type === 'CallExpression' &&
+    node.callee.type === 'MemberExpression' &&
+    node.callee.property.type === 'Identifier' &&
+    ITERATOR_RETURNING_METHODS.has(node.callee.property.name) &&
+    !(
+      node.callee.object.type === 'Identifier' &&
+      node.callee.object.name === 'Object'
+    )
+  );
+}
+
+function isKnownNonArrayCopySource(node: TSESTree.Node): boolean {
+  return (
+    isIteratorReturningCall(node) ||
+    (node.type === 'NewExpression' &&
+      node.callee.type === 'Identifier' &&
+      NON_ARRAY_COPY_SOURCE_CTORS.has(node.callee.name))
+  );
+}
+
+function resolvesToKnownNonArrayCopySource(
+  node: TSESTree.Node,
+  context: TSESLint.RuleContext<MessageIds, []>
+): boolean {
+  if (isKnownNonArrayCopySource(node)) {
+    return true;
+  }
+
+  if (node.type !== 'Identifier') {
+    return false;
+  }
+
+  const variable = context.sourceCode
+    .getScope(node)
+    .references.find((ref) => ref.identifier === node)?.resolved;
+
+  if (!variable || variable.defs.length !== 1) {
+    return false;
+  }
+
+  const def = variable.defs[0];
+  if (!def || (def.type !== 'Variable' && def.type !== 'Parameter')) {
+    return false;
+  }
+
+  if (hasKnownNonArrayTypeAnnotation(def.name)) {
+    return true;
+  }
+
+  if (def.type !== 'Variable' || def.node.type !== 'VariableDeclarator') {
+    return false;
+  }
+
+  const init = def.node.init;
+
+  return (
+    init !== null &&
+    isKnownNonArrayCopySource(init) &&
+    variable.references.every((ref) => !ref.isWrite() || ref.writeExpr === init)
+  );
+}
+
 export const preferArrayToSorted: TSESLint.RuleModule<MessageIds, []> = {
   meta: {
     type: 'suggestion',
@@ -40,7 +150,15 @@ export const preferArrayToSorted: TSESLint.RuleModule<MessageIds, []> = {
         const arrayNode = getArrayFromCopyPattern(sortCallee);
 
         if (arrayNode) {
-          if (isArrayType(arrayNode, context) === false) {
+          const arrayType = isArrayType(arrayNode, context);
+          if (arrayType === false) {
+            return;
+          }
+
+          if (
+            arrayType !== true &&
+            resolvesToKnownNonArrayCopySource(arrayNode, context)
+          ) {
             return;
           }