fix(eslint-plugin): [no-confusing-void-expression] handle unfixable c…

…ases (#7674) * fix(eslint-plugin): [no-confusing-void-expression] handle unfixable cases * Fix post-merge issues --------- Co-authored-by: Josh Goldberg ✨ <git@joshuakgoldberg.com>
typescript-eslint · Oct 16, 2023 · 7e52f27 · 7e52f27
1 parent d475f88
commit 7e52f27
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Showing 2 changed files with 101 additions and 3 deletions.
diff --git a/packages/eslint-plugin/src/rules/no-confusing-void-expression.ts b/packages/eslint-plugin/src/rules/no-confusing-void-expression.ts
@@ -127,6 +127,9 @@ export default createRule<Options, MessageId>({
             node,
             messageId: 'invalidVoidExprArrow',
             fix(fixer) {
+              if (!canFix(arrowFunction)) {
+                return null;
+              }
               const arrowBody = arrowFunction.body;
               const arrowBodyText = sourceCode.getText(arrowBody);
               const newArrowBodyText = `{ ${arrowBodyText}; }`;
@@ -169,6 +172,9 @@ export default createRule<Options, MessageId>({
               node,
               messageId: 'invalidVoidExprReturnLast',
               fix(fixer) {
+                if (!canFix(returnStmt)) {
+                  return null;
+                }
                 const returnValue = returnStmt.argument!;
                 const returnValueText = sourceCode.getText(returnValue);
                 let newReturnStmtText = `${returnValueText};`;
@@ -337,5 +343,19 @@ export default createRule<Options, MessageId>({
 
       return ['(', '[', '`'].includes(startToken.value);
     }
+
+    function canFix(
+      node: TSESTree.ReturnStatement | TSESTree.ArrowFunctionExpression,
+    ): boolean {
+      const services = getParserServices(context);
+
+      const targetNode =
+        node.type === AST_NODE_TYPES.ReturnStatement
+          ? node.argument!
+          : node.body;
+
+      const type = getConstrainedTypeAtLocation(services, targetNode);
+      return tsutils.isTypeFlagSet(type, ts.TypeFlags.VoidLike);
+    }
   },
 });
diff --git a/packages/eslint-plugin/tests/rules/no-confusing-void-expression.test.ts b/packages/eslint-plugin/tests/rules/no-confusing-void-expression.test.ts
@@ -199,12 +199,25 @@ function notcool(input: string) {
     {
       code: 'foo => foo && console.log(foo);',
       errors: [{ line: 1, column: 15, messageId: 'invalidVoidExprArrow' }],
-      output: `foo => { foo && console.log(foo); };`,
+    },
+    {
+      code: '(foo: undefined) => foo && console.log(foo);',
+      errors: [{ line: 1, column: 28, messageId: 'invalidVoidExprArrow' }],
+      output: `(foo: undefined) => { foo && console.log(foo); };`,
     },
     {
       code: 'foo => foo || console.log(foo);',
       errors: [{ line: 1, column: 15, messageId: 'invalidVoidExprArrow' }],
-      output: `foo => { foo || console.log(foo); };`,
+    },
+    {
+      code: '(foo: undefined) => foo || console.log(foo);',
+      errors: [{ line: 1, column: 28, messageId: 'invalidVoidExprArrow' }],
+      output: `(foo: undefined) => { foo || console.log(foo); };`,
+    },
+    {
+      code: '(foo: void) => foo || console.log(foo);',
+      errors: [{ line: 1, column: 23, messageId: 'invalidVoidExprArrow' }],
+      output: `(foo: void) => { foo || console.log(foo); };`,
     },
     {
       code: 'foo => (foo ? console.log(true) : console.log(false));',
@@ -310,7 +323,72 @@ function notcool(input: string) {
         };
       `,
     },
-
+    {
+      code: `
+        const f = function () {
+          let num = 1;
+          return num ? console.log('foo') : num;
+        };
+      `,
+      errors: [{ line: 4, column: 24, messageId: 'invalidVoidExprReturnLast' }],
+    },
+    {
+      code: `
+        const f = function () {
+          let undef = undefined;
+          return undef ? console.log('foo') : undef;
+        };
+      `,
+      errors: [{ line: 4, column: 26, messageId: 'invalidVoidExprReturnLast' }],
+      output: `
+        const f = function () {
+          let undef = undefined;
+          undef ? console.log('foo') : undef;
+        };
+      `,
+    },
+    {
+      code: `
+        const f = function () {
+          let num = 1;
+          return num || console.log('foo');
+        };
+      `,
+      errors: [{ line: 4, column: 25, messageId: 'invalidVoidExprReturnLast' }],
+    },
+    {
+      code: `
+        const f = function () {
+          let bar = void 0;
+          return bar || console.log('foo');
+        };
+      `,
+      errors: [{ line: 4, column: 25, messageId: 'invalidVoidExprReturnLast' }],
+      output: `
+        const f = function () {
+          let bar = void 0;
+          bar || console.log('foo');
+        };
+      `,
+    },
+    {
+      code: `
+        let num = 1;
+        const foo = () => (num ? console.log('foo') : num);
+      `,
+      errors: [{ line: 3, column: 34, messageId: 'invalidVoidExprArrow' }],
+    },
+    {
+      code: `
+        let bar = void 0;
+        const foo = () => (bar ? console.log('foo') : bar);
+      `,
+      errors: [{ line: 3, column: 34, messageId: 'invalidVoidExprArrow' }],
+      output: `
+        let bar = void 0;
+        const foo = () => { bar ? console.log('foo') : bar; };
+      `,
+    },
     {
       options: [{ ignoreVoidOperator: true }],
       code: "return console.log('foo');",