typescript-eslint · bradzacher · Jan 12, 2024 · Dec 18, 2023 · Dec 18, 2023 · Jan 11, 2024
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts b/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
@@ -530,7 +530,7 @@ export default createRule<Options, MessageId>({
          propertyType.value.toString(),
        );
        if (propType) {
-          return isNullableType(propType, { allowUndefined: true });
+          return isNullableType(propType);
        }
      }
      const typeName = getTypeName(checker, propertyType);
@@ -568,14 +568,12 @@ export default createRule<Options, MessageId>({
          );

          if (propType) {
-            return isNullableType(propType, { allowUndefined: true });
+            return isNullableType(propType);
          }

          return !!checker.getIndexInfoOfType(type, ts.IndexKind.String);
        });
-        return (
-          !isOwnNullable && isNullableType(prevType, { allowUndefined: true })
-        );
+        return !isOwnNullable && isNullableType(prevType);
      }
      return false;
    }
@@ -612,8 +610,7 @@ export default createRule<Options, MessageId>({
      const possiblyVoid = isTypeFlagSet(type, ts.TypeFlags.Void);
      return (
        isTypeFlagSet(type, ts.TypeFlags.Any | ts.TypeFlags.Unknown) ||
-        (isOwnNullable &&
-          (isNullableType(type, { allowUndefined: true }) || possiblyVoid))
+        (isOwnNullable && (isNullableType(type) || possiblyVoid))
      );
    }


diff --git a/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts b/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
@@ -309,8 +309,7 @@ export default createRule<Options, MessageIds>({
      ): void {
        const tsNode = parserServices.esTreeNodeToTSNodeMap.get(node);
        const type = checker.getTypeAtLocation(tsNode.left);
-        const isNullish = isNullableType(type, { allowUndefined: true });
-        if (!isNullish) {
+        if (!isNullableType(type)) {
          return;
        }


diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts
@@ -48,6 +48,11 @@ const foo = { 0: 'hello', 5: 'hello' } as PossibleTuple;
    `
 let bar: number | undefined = x;
 let foo: number = bar!;
+    `,
+    `
+declare const a: { data?: unknown };
+
+const x = a.data!;
    `,
    {
      code: `

diff --git a/packages/type-utils/src/predicates.ts b/packages/type-utils/src/predicates.ts
@@ -2,15 +2,18 @@ import debug from 'debug';
 import * as tsutils from 'ts-api-utils';
 import * as ts from 'typescript';

-import { getTypeFlags, isTypeFlagSet } from './typeFlagUtils';
+import { isTypeFlagSet } from './typeFlagUtils';

 const log = debug('typescript-eslint:eslint-plugin:utils:types');

 export interface IsNullableTypeOptions {
  /**
-   * Whether the type is a receiving type (i.e. the type of a called function's parameter).
+   * @deprecated - this flag no longer does anything and will be removed in the next major
   */
  isReceiver?: boolean;
+  /**
+   * @deprecated - this flag no longer does anything and will be removed in the next major
+   */
  allowUndefined?: boolean;
 }

@@ -19,18 +22,15 @@ export interface IsNullableTypeOptions {
 */
 export function isNullableType(
  type: ts.Type,
-  { isReceiver = false, allowUndefined = true }: IsNullableTypeOptions = {},
+  _deprecated?: IsNullableTypeOptions,
 ): boolean {
-  const flags = getTypeFlags(type);
-
-  if (isReceiver && flags & (ts.TypeFlags.Any | ts.TypeFlags.Unknown)) {
-    return true;
-  }
-
-  if (allowUndefined) {
-    return (flags & (ts.TypeFlags.Null | ts.TypeFlags.Undefined)) !== 0;
-  }
-  return (flags & ts.TypeFlags.Null) !== 0;
+  return isTypeFlagSet(
+    type,
+    ts.TypeFlags.Any |
+      ts.TypeFlags.Unknown |
+      ts.TypeFlags.Null |
+      ts.TypeFlags.Undefined,
+  );
 }

 /**