Merge branch 'main' into main

typescript-eslint · Jan 21, 2024 · 445be6f · 445be6f
2 parents 4028ef7 + 920f909
commit 445be6f
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Showing 2 changed files with 29 additions and 3 deletions.
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts b/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
@@ -271,7 +271,10 @@ export default createRule<Options, MessageId>({
       if (
         isTypeFlagSet(
           type,
-          ts.TypeFlags.Any | ts.TypeFlags.Unknown | ts.TypeFlags.TypeParameter,
+          ts.TypeFlags.Any |
+            ts.TypeFlags.Unknown |
+            ts.TypeFlags.TypeParameter |
+            ts.TypeFlags.TypeVariable,
         )
       ) {
         return;
@@ -345,7 +348,8 @@ export default createRule<Options, MessageId>({
           flag |=
             ts.TypeFlags.Any |
             ts.TypeFlags.Unknown |
-            ts.TypeFlags.TypeParameter;
+            ts.TypeFlags.TypeParameter |
+            ts.TypeFlags.TypeVariable;
 
           // Allow loose comparison to nullish values.
           if (node.operator === '==' || node.operator === '!=') {

diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
@@ -253,6 +253,11 @@ function test<T>(a: T) {
   const t16 = undefined !== a;
 }
     `,
+    `
+function foo<T extends object>(arg: T, key: keyof T): void {
+  arg[key] == null;
+}
+    `,
 
     // Predicate functions
     `
@@ -317,6 +322,11 @@ function test<T>(a: T) {
     `
 function test<T extends string | null>(a: T) {
   return a ?? 'default';
+}
+    `,
+    `
+function foo<T extends object>(arg: T, key: keyof T): void {
+  arg[key] ?? 'default';
 }
     `,
     // Indexing cases
@@ -740,6 +750,11 @@ foo ||= 1;
     `
 declare let foo: number;
 foo &&= 1;
+    `,
+    `
+function foo<T extends object>(arg: T, key: keyof T): void {
+  arg[key] ??= 'default';
+}
     `,
     // https://github.com/typescript-eslint/typescript-eslint/issues/6264
     `
@@ -1084,7 +1099,14 @@ function test(a: never) {
       `,
       errors: [ruleError(3, 10, 'never')],
     },
-
+    {
+      code: `
+function test<T extends { foo: number }, K extends 'foo'>(num: T[K]) {
+  num ?? 'default';
+}
+      `,
+      errors: [ruleError(3, 3, 'neverNullish')],
+    },
     // Predicate functions
     {
       code: `