fix(eslint-plugin): [prefer-nullish-coalescing] treat any/unknown as non-nullable (typescript-eslint#8262)

auvred · danvk · commit 2ecc5e7b1168 · 2024-02-04T16:48:17.000-05:00
* fix(eslint-plugin): [prefer-nullish-coalescing] treat any/unknown as non-nullable

* chore: rm unrelated changes

* test: add declarations of 'y' variable
diff --git a/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts b/packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
@@ -10,8 +10,8 @@ import {
   getTypeFlags,
   isLogicalOrOperator,
   isNodeEqual,
-  isNullableType,
   isNullLiteral,
+  isTypeFlagSet,
   isUndefinedIdentifier,
   nullThrows,
   NullThrowsReasons,
@@ -309,7 +309,7 @@ export default createRule<Options, MessageIds>({
       ): void {
         const tsNode = parserServices.esTreeNodeToTSNodeMap.get(node);
         const type = checker.getTypeAtLocation(tsNode.left);
-        if (!isNullableType(type)) {
+        if (!isTypeFlagSet(type, ts.TypeFlags.Null | ts.TypeFlags.Undefined)) {
           return;
         }
 
diff --git a/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts b/packages/eslint-plugin/tests/rules/prefer-nullish-coalescing.test.ts
@@ -222,6 +222,21 @@ x || y;
       `,
       options: [{ ignorePrimitives: true }],
     })),
+    `
+      declare const x: any;
+      declare const y: number;
+      x || y;
+    `,
+    `
+      declare const x: unknown;
+      declare const y: number;
+      x || y;
+    `,
+    `
+      declare const x: never;
+      declare const y: number;
+      x || y;
+    `,
   ],
   invalid: [
     ...nullishTypeInvalidTest((nullish, type) => ({
