From ad888b7faec116ee2e66fc3a6891ee321bd38c65 Mon Sep 17 00:00:00 2001
From: Joshua Chen <sidachen2003@gmail.com>
Date: Sat, 21 May 2022 13:07:31 +0800
Subject: [PATCH] fix(utils): avoid replacing Markdown links missing the
 directly next link (#7458)

---
 .../__snapshots__/markdownLinks.test.ts.snap  |  7 ++++
 .../src/__tests__/markdownLinks.test.ts       | 33 +++++++++++++++++--
 .../docusaurus-utils/src/markdownLinks.ts     |  3 ++
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/packages/docusaurus-utils/src/__tests__/__snapshots__/markdownLinks.test.ts.snap b/packages/docusaurus-utils/src/__tests__/__snapshots__/markdownLinks.test.ts.snap
index 56c08fd6f9e1..1ff0a5351c06 100644
--- a/packages/docusaurus-utils/src/__tests__/__snapshots__/markdownLinks.test.ts.snap
+++ b/packages/docusaurus-utils/src/__tests__/__snapshots__/markdownLinks.test.ts.snap
@@ -135,6 +135,13 @@ The following operations are defined for [URI]s:
 }
 `;
 
+exports[`replaceMarkdownLinks replaces two links on the same line 1`] = `
+{
+  "brokenMarkdownLinks": [],
+  "newContent": "[TypeScript](/programming-languages/typescript/) and [Go](/programming-languages/go/)",
+}
+`;
+
 exports[`replaceMarkdownLinks resolves absolute and relative links differently 1`] = `
 {
   "brokenMarkdownLinks": [
diff --git a/packages/docusaurus-utils/src/__tests__/markdownLinks.test.ts b/packages/docusaurus-utils/src/__tests__/markdownLinks.test.ts
index d47b3ab3e2db..866e3594d47a 100644
--- a/packages/docusaurus-utils/src/__tests__/markdownLinks.test.ts
+++ b/packages/docusaurus-utils/src/__tests__/markdownLinks.test.ts
@@ -38,6 +38,35 @@ describe('replaceMarkdownLinks', () => {
     ).toMatchSnapshot();
   });
 
+  it('replaces two links on the same line', () => {
+    // cSpell:ignore Goooooooooo
+    // This is a very arcane bug: if we continue matching using the previous
+    // matching index (as is the behavior of RegExp#exec), it will go right over
+    // the next Markdown link and fail to match the "Go" link. This only happens
+    // when: (1) the replaced link is much shorter than the Markdown path, (2)
+    // the next link is very close to the current one (e.g. here if it's not
+    // "Go" but "Goooooooooo", or if every link has the /docs/ prefix, the bug
+    // will not trigger because it won't overshoot)
+    expect(
+      replaceMarkdownLinks({
+        siteDir: '.',
+        filePath: 'docs/intro.md',
+        contentPaths: {
+          contentPath: 'docs',
+          contentPathLocalized: 'i18n/docs-localized',
+        },
+        sourceToPermalink: {
+          '@site/docs/intro.md': '/',
+          '@site/docs/programming-languages/typescript/typescript.md':
+            '/programming-languages/typescript/',
+          '@site/docs/programming-languages/go/go.md':
+            '/programming-languages/go/',
+        },
+        fileString: `[TypeScript](programming-languages/typescript/typescript.md) and [Go](programming-languages/go/go.md)`,
+      }),
+    ).toMatchSnapshot();
+  });
+
   it('replaces reference style Markdown links', () => {
     expect(
       replaceMarkdownLinks({
@@ -155,7 +184,7 @@ The following operations are defined for [URI]s:
     ).toMatchSnapshot();
   });
 
-  // TODO bad
+  // FIXME
   it('ignores links in inline code', () => {
     expect(
       replaceMarkdownLinks({
@@ -175,7 +204,7 @@ The following operations are defined for [URI]s:
     ).toMatchSnapshot();
   });
 
-  // TODO bad
+  // FIXME
   it('replaces links with same title as URL', () => {
     expect(
       replaceMarkdownLinks({
diff --git a/packages/docusaurus-utils/src/markdownLinks.ts b/packages/docusaurus-utils/src/markdownLinks.ts
index 3a7966ad8db7..c83bffeb406c 100644
--- a/packages/docusaurus-utils/src/markdownLinks.ts
+++ b/packages/docusaurus-utils/src/markdownLinks.ts
@@ -138,6 +138,9 @@ export function replaceMarkdownLinks<T extends ContentPaths>({
           .map((part) => part.replace(/\s/g, '%20'))
           .join('/');
         modifiedLine = modifiedLine.replace(mdLink, encodedPermalink);
+        // Adjust the lastIndex to avoid passing over the next link if the
+        // newly replaced URL is shorter.
+        mdRegex.lastIndex += encodedPermalink.length - mdLink.length;
       } else {
         const brokenMarkdownLink: BrokenMarkdownLink<T> = {
           contentPaths,