Preserve trailing double spaces in JSDoc (#18594)

Co-authored-by: fisker <lionkay@gmail.com>

changelog_unreleased/javascript/18594.md

@@ -0,0 +1,13 @@
+#### Preserve trailing double spaces in JSDoc (#18594 by @seiyab)
+
+Some tools treat these spaces as meaningful.
+
+```bash
+await require('prettier').format('/**\n * With 2 spaces   \n */', {parser: 'babel'});
+
+# Prettier stable
+// -> '/**\n * With 2 spaces\n */\n'
+
+# Prettier main
+// -> '/**\n * With 2 spaces  \n */\n'
+```

src/language-js/print/comment.js

@@ -1,9 +1,19 @@
-import { hardline, join, replaceEndOfLine } from "../../document/index.js";
+import {
+  hardline,
+  literalline,
+  markAsRoot,
+  replaceEndOfLine,
+} from "../../document/index.js";
 import { locEnd, locStart } from "../loc.js";
 import isBlockComment from "../utilities/is-block-comment.js";
 import isIndentableBlockComment from "../utilities/is-indentable-block-comment.js";
 import isLineComment from "../utilities/is-line-comment.js";
 
+/**
+@import {Doc} from "../../document/index.js"
+@import {Comment} from "../types/estree.js"
+*/
+
 function printComment(path, options) {
   const comment = path.node;
 
@@ -26,19 +36,33 @@ function printComment(path, options) {
   throw new Error("Not a comment: " + JSON.stringify(comment));
 }
 
+/**
+@param {Comment} comment
+@returns {Doc}
+*/
 function printIndentableBlockComment(comment) {
   const lines = comment.value.split("\n");
+  const isJsdoc = comment.value[0] === "*" && comment.value[1] !== "*";
 
   return [
     "/*",
-    join(
-      hardline,
-      lines.map((line, index) =>
-        index === 0
-          ? line.trimEnd()
-          : " " + (index < lines.length - 1 ? line.trim() : line.trimStart()),
-      ),
-    ),
+    lines.map((line, index) => {
+      if (index === 0) {
+        return [line.trimEnd(), hardline];
+      }
+
+      if (index === lines.length - 1) {
+        return [" ", line.trimStart()];
+      }
+
+      const trimmed = line.trim();
+      const content = [" ", trimmed];
+      if (isJsdoc && trimmed !== "*" && line.endsWith("  ")) {
+        return [content, "  ", markAsRoot(literalline)];
+      }
+
+      return [content, hardline];
+    }),
     "*/",
   ];
 }

tests/format/js/comments/__snapshots__/format.test.js.snap

@@ -3374,6 +3374,7 @@ function HelloWorld() {
         </div>
     );
 }
+
 =====================================output=====================================
 /** @type {any} */
 const x = (
@@ -3437,6 +3438,7 @@ function HelloWorld() {
         </div>
     );
 }
+
 =====================================output=====================================
 /** @type {any} */
 const x = (

tests/format/js/comments/jsdoc.js

@@ -23,4 +23,4 @@ function HelloWorld() {
            <span>Test</span>
         </div>
     );
-}
+}

tests/format/js/comments/trailing-spaces/format.test.js

@@ -0,0 +1,124 @@
+import { outdent } from "outdent";
+
+const fixtures = {
+  importMeta: import.meta,
+  snippets: [
+    {
+      name: "Preserve trailing double spaces in JSDoc",
+      code: outdent`
+        /**
+         * 2 spaces.${" ".repeat(2)}
+         */
+      `,
+      output: outdent`
+        /**
+         * 2 spaces.${" ".repeat(2)}
+         */\n
+      `,
+    },
+    {
+      name: "Misaligned",
+      code: outdent`
+        /**
+           * 2 spaces.${" ".repeat(2)}
+        */
+      `,
+      output: outdent`
+        /**
+         * 2 spaces.${" ".repeat(2)}
+         */\n
+      `,
+    },
+    {
+      name: "Non-top-level",
+      code: outdent`
+        function foo() {
+                /**
+                 * 2 spaces.${" ".repeat(2)}
+                 */
+        }
+      `,
+      output: outdent`
+        function foo() {
+          /**
+           * 2 spaces.${" ".repeat(2)}
+           */
+        }\n
+      `,
+    },
+    {
+      name: "Preserve trailing 2+ spaces in JSDoc",
+      code: outdent`
+        /**
+         * 3 spaces.${" ".repeat(3)}
+         */
+      `,
+      output: outdent`
+        /**
+         * 3 spaces.${" ".repeat(2)}
+         */\n
+      `,
+    },
+    {
+      name: "Spaces on start line",
+      code: outdent`
+        /**${" ".repeat(2)}
+         * 2 spaces.${" ".repeat(2)}
+         */
+      `,
+      output: outdent`
+        /**
+         * 2 spaces.${" ".repeat(2)}
+         */\n
+      `,
+    },
+    {
+      name: "Remove on blank line",
+      code: outdent`
+        /**
+         *${" ".repeat(2)}
+         */
+      `,
+      output: outdent`
+        /**
+         *
+         */\n
+      `,
+    },
+    {
+      name: "Remove trailing single space in JSDoc",
+      code: outdent`
+        /**
+         * 1 space.${" ".repeat(1)}
+         */
+      `,
+      output: outdent`
+        /**
+         * 1 space.
+         */\n
+      `,
+    },
+    /*
+    > Each comment must start with a `/**` sequence in order to be recognized by the JSDoc parser.
+    > Comments beginning with `/*`, `/***`, or more than 3 stars will be ignored.
+    > This is a feature to allow you to suppress parsing of comment blocks.
+
+    https://jsdoc.app/about-getting-started
+    */
+    {
+      name: "Remove trailing single space in non-JSDoc",
+      code: outdent`
+        /***
+          * NOT JSDOC.${" ".repeat(2)}
+          */
+      `,
+      output: outdent`
+        /***
+         * NOT JSDOC.
+         */\n
+      `,
+    },
+  ],
+};
+
+runFormatTest(fixtures, ["babel", "flow", "typescript"]);

tests/format/vue/comments/trailing-spaces-in-js-comment/format.test.js

@@ -0,0 +1,34 @@
+import { outdent } from "outdent";
+
+const fixtures = {
+  importMeta: import.meta,
+  snippets: [
+    {
+      name: "Preserve trailing double spaces in JSDoc",
+      code: outdent`
+        <script>
+        function foo
+        (
+                              uglyParameter,
+        toEnsure, thisCode,
+        isFormatted, byJsParser) {
+          /**
+          * Should not break when html parser add indention.${" ".repeat(2)}
+          */
+        }
+        </script>
+      `,
+      output: outdent`
+        <script>
+          function foo(uglyParameter, toEnsure, thisCode, isFormatted, byJsParser) {
+            /**
+             * Should not break when html parser add indention.${" ".repeat(2)}
+             */
+          }
+        </script>\n
+      `,
+    },
+  ],
+};
+
+runFormatTest(fixtures, ["vue"], { vueIndentScriptAndStyle: true });