TypeScript: Fix missing comments in MethodDefinition (#9872)

changelog_unreleased/typescript/9872.md

@@ -0,0 +1,19 @@
+#### Fix missing comments in `MethodDefinition` (#9872 by @fisker)
+
+`typescript` parser only, `babel-ts` don't have this issue.
+
+<!-- prettier-ignore -->
+```typescript
+// Input
+class Foo {
+  bar() /* bat */;
+}
+
+// Prettier stable
+Error: Comment "bat" was not printed. Please report this error!
+
+// Prettier master
+class Foo {
+  bar /* bat */();
+}
+```

src/language-js/comments.js

@@ -531,7 +531,8 @@ function handleCommentInEmptyParens({ comment, enclosingNode, text }) {
   }
   if (
     enclosingNode &&
-    enclosingNode.type === "MethodDefinition" &&
+    (enclosingNode.type === "MethodDefinition" ||
+      enclosingNode.type === "TSAbstractMethodDefinition") &&
     getFunctionParameters(enclosingNode.value).length === 0
   ) {
     addDanglingComment(enclosingNode.value, comment);

src/language-js/print/function.js

@@ -95,12 +95,19 @@ function printMethod(path, options, print) {
 
   parts.push(
     printPropertyKey(path, options, print),
-    node.optional || node.key.optional ? "?" : "",
-    node === value
-      ? printMethodInternal(path, options, print)
-      : path.call((path) => printMethodInternal(path, options, print), "value")
+    node.optional || node.key.optional ? "?" : ""
   );
 
+  if (node === value) {
+    parts.push(printMethodInternal(path, options, print));
+  } else if (value.type === "FunctionExpression") {
+    parts.push(
+      path.call((path) => printMethodInternal(path, options, print), "value")
+    );
+  } else {
+    parts.push(path.call(print, "value"));
+  }
+
   return concat(parts);
 }
 
@@ -371,5 +378,6 @@ module.exports = {
   printMethod,
   printReturnStatement,
   printThrowStatement,
+  printMethodInternal,
   shouldPrintParamsWithoutParens,
 };

src/language-js/print/typescript.js

@@ -34,7 +34,7 @@ const {
   printTypeParameters,
 } = require("./type-parameters");
 const { printPropertyKey } = require("./property");
-const { printFunctionDeclaration } = require("./function");
+const { printFunctionDeclaration, printMethodInternal } = require("./function");
 const { printInterface } = require("./interface");
 const { printAssignmentRight } = require("./assignment");
 const { printBlock } = require("./block");
@@ -546,6 +546,8 @@ function printTypescript(path, options, print) {
       ]);
     case "TSTypeAnnotation":
       return path.call(print, "typeAnnotation");
+    case "TSEmptyBodyFunctionExpression":
+      return printMethodInternal(path, options, print);
 
     // These are not valid TypeScript. Printing them just for the sake of error recovery.
     case "TSJSDocAllType":

src/language-js/printer-estree.js

@@ -1276,7 +1276,9 @@ function canAttachComment(node) {
     !isLineComment(node) &&
     node.type !== "EmptyStatement" &&
     node.type !== "TemplateElement" &&
-    node.type !== "Import"
+    node.type !== "Import" &&
+    // `babel-ts` don't have similar node for `class Foo { bar() /* bat */; }`
+    node.type !== "TSEmptyBodyFunctionExpression"
   );
 }
 

tests/typescript/class/__snapshots__/jsfmt.spec.js.snap

@@ -72,6 +72,38 @@ class F<__T> {}
 ================================================================================
 `;
 
+exports[`empty-method-body.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+// #9324
+
+class foo1 {
+  bar() /* bat */;
+}
+
+// #9367
+class Test {
+  foo (/* 2 */) /* 3 */;
+}
+
+=====================================output=====================================
+// #9324
+
+class foo1 {
+  bar /* bat */();
+}
+
+// #9367
+class Test {
+  foo /* 3 */(/* 2 */);
+}
+
+================================================================================
+`;
+
 exports[`extends_implements.ts format 1`] = `
 ====================================options=====================================
 parsers: ["typescript"]

tests/typescript/class/empty-method-body.ts

@@ -0,0 +1,10 @@
+// #9324
+
+class foo1 {
+  bar() /* bat */;
+}
+
+// #9367
+class Test {
+  foo (/* 2 */) /* 3 */;
+}