feat(type-utils): isNullableType add Void logic (typescript-eslint#9937)

developer-bandi · web-flow · commit 3710c9c32c8b · 2024-09-12T09:32:59.000-04:00
* fix: isNullableType util add Void

* fix: lint error
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts b/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
@@ -644,10 +644,9 @@ export default createRule<Options, MessageId>({
             ? !isCallExpressionNullableOriginFromCallee(node)
             : true;
 
-      const possiblyVoid = isTypeFlagSet(type, ts.TypeFlags.Void);
       return (
         isTypeFlagSet(type, ts.TypeFlags.Any | ts.TypeFlags.Unknown) ||
-        (isOwnNullable && (isNullableType(type) || possiblyVoid))
+        (isOwnNullable && isNullableType(type))
       );
     }
 
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts b/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts
@@ -243,7 +243,7 @@ export default createRule<Options, MessageIds>({
 
         const type = getConstrainedTypeAtLocation(services, node.expression);
 
-        if (!isNullableType(type) && !isTypeFlagSet(type, ts.TypeFlags.Void)) {
+        if (!isNullableType(type)) {
           if (
             node.expression.type === AST_NODE_TYPES.Identifier &&
             isPossiblyUsedBeforeAssigned(node.expression)
diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
@@ -867,6 +867,15 @@ foo?.()?.toExponential();
 type Foo = { [key: string]: () => number | undefined } | null;
 declare const foo: Foo;
 foo?.['bar']()?.toExponential();
+    `,
+    `
+declare function foo(): void | { key: string };
+const bar = foo()?.key;
+    `,
+    `
+type fn = () => void;
+declare function foo(): void | fn;
+const bar = foo()?.();
     `,
     {
       languageOptions: { parserOptions: optionsWithExactOptionalPropertyTypes },
diff --git a/packages/type-utils/src/predicates.ts b/packages/type-utils/src/predicates.ts
@@ -15,7 +15,8 @@ export function isNullableType(type: ts.Type): boolean {
     ts.TypeFlags.Any |
       ts.TypeFlags.Unknown |
       ts.TypeFlags.Null |
-      ts.TypeFlags.Undefined,
+      ts.TypeFlags.Undefined |
+      ts.TypeFlags.Void,
   );
 }
 

Original file line number	Diff line number	Diff line change
`@@ -15,7 +15,8 @@ export function isNullableType(type: ts.Type): boolean {`
`15`	`15`	`ts.TypeFlags.Any \|`
`16`	`16`	`ts.TypeFlags.Unknown \|`
`17`	`17`	`ts.TypeFlags.Null \|`
`18`		`- ts.TypeFlags.Undefined,`
	`18`	`+ ts.TypeFlags.Undefined \|`
	`19`	`+ ts.TypeFlags.Void,`
`19`	`20`	`);`
`20`	`21`	`}`
`21`	`22`