Fix missing parentheses in ConditionalTypeAnnotation

fisker · fisker · commit 543d87a8b027 · 2025-02-27T20:14:33.000+08:00
diff --git a/src/language-js/needs-parens.js b/src/language-js/needs-parens.js
@@ -10,10 +10,13 @@ import {
   isBinaryCastExpression,
   isBitwiseOperator,
   isCallExpression,
+  isConditionalType,
+  isIntersectionType,
   isMemberExpression,
   isNullishCoalescing,
   isObjectOrRecordExpression,
   isObjectProperty,
+  isUnionType,
   shouldFlatten,
   startsWithNoLookaheadToken,
 } from "./utils/index.js";
@@ -525,11 +528,20 @@ function needsParens(path, options) {
     // fallthrough
     case "TSConditionalType":
     case "TSConstructorType":
-      if (key === "extendsType" && parent.type === "TSConditionalType") {
-        if (node.type === "TSConditionalType") {
-          return true;
-        }
+    case "ConditionalTypeAnnotation":
+      if (
+        key === "extendsType" &&
+        isConditionalType(node) &&
+        parent.type === node.type
+      ) {
+        return true;
+      }
+
+      if (key === "checkType" && isConditionalType(parent)) {
+        return true;
+      }
 
+      if (key === "extendsType" && parent.type === "TSConditionalType") {
         let { typeAnnotation } = node.returnType || node.typeAnnotation;
 
         if (
@@ -547,15 +559,11 @@ function needsParens(path, options) {
         }
       }
 
-      if (key === "checkType" && parent.type === "TSConditionalType") {
-        return true;
-      }
     // fallthrough
     case "TSUnionType":
     case "TSIntersectionType":
       if (
-        (parent.type === "TSUnionType" ||
-          parent.type === "TSIntersectionType") &&
+        (isUnionType(parent) || isIntersectionType(parent)) &&
         parent.types.length > 1 &&
         (!node.types || node.types.length > 1)
       ) {
@@ -706,19 +714,6 @@ function needsParens(path, options) {
       );
     }
 
-    case "ConditionalTypeAnnotation":
-      if (
-        key === "extendsType" &&
-        parent.type === "ConditionalTypeAnnotation" &&
-        node.type === "ConditionalTypeAnnotation"
-      ) {
-        return true;
-      }
-
-      if (key === "checkType" && parent.type === "ConditionalTypeAnnotation") {
-        return true;
-      }
-
     // fallthrough
     case "OptionalIndexedAccessType":
       return key === "objectType" && parent.type === "IndexedAccessType";
diff --git a/src/language-js/utils/index.js b/src/language-js/utils/index.js
@@ -1060,13 +1060,18 @@ const isBinaryCastExpression = createTypeCheckFunction([
 ]);
 
 const isUnionType = createTypeCheckFunction([
-  "UnionTypeAnnotation",
   "TSUnionType",
+  "UnionTypeAnnotation",
 ]);
 
 const isIntersectionType = createTypeCheckFunction([
-  "IntersectionTypeAnnotation",
   "TSIntersectionType",
+  "IntersectionTypeAnnotation",
+]);
+
+const isConditionalType = createTypeCheckFunction([
+  "TSConditionalType",
+  "ConditionalTypeAnnotation",
 ]);
 
 export {
@@ -1092,6 +1097,7 @@ export {
   isBitwiseOperator,
   isCallExpression,
   isCallLikeExpression,
+  isConditionalType,
   isExportDeclaration,
   isFlowObjectTypePropertyAFunction,
   isFunctionCompositionArgs,
diff --git a/tests/format/flow/conditional-types/parentheses/format.test.js b/tests/format/flow/conditional-types/parentheses/format.test.js
@@ -0,0 +1,5 @@
+runFormatTest(import.meta, ["flow", "typescript"], {
+  errors: {
+    "babel-flow": true,
+  },
+});
diff --git a/tests/format/flow/conditional-types/parentheses/union.js b/tests/format/flow/conditional-types/parentheses/union.js
@@ -0,0 +1,2 @@
+type T<U> = 'a' | ('b' extends U ? 'c' : empty);
+type T<U> = 'a' & ('b' extends U ? 'c' : empty);

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+type T<U> = 'a' \| ('b' extends U ? 'c' : empty);`
	`2`	`+type T<U> = 'a' & ('b' extends U ? 'c' : empty);`