From ff379ff0e6410f15632fbd2d21c6cd5e865cd189 Mon Sep 17 00:00:00 2001
From: Liam Miller-Cushon <cushon@google.com>
Date: Sat, 10 Aug 2024 11:25:27 -0700
Subject: [PATCH] Fix a crash in InvalidLink on `///` markdown doc comments

`[foo]` is getting 'desugared' to a link node for `{@link foo}` that doesn't have a start position, for now this change avoids a crash and skip emitting a fix for that case.

PiperOrigin-RevId: 661643507
---
 .../google/errorprone/util/RuntimeVersion.java  |  5 +++++
 .../errorprone/bugpatterns/javadoc/Utils.java   |  2 +-
 .../bugpatterns/javadoc/InvalidLinkTest.java    | 17 +++++++++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/check_api/src/main/java/com/google/errorprone/util/RuntimeVersion.java b/check_api/src/main/java/com/google/errorprone/util/RuntimeVersion.java
index 0785489c6450..28e95215a2a6 100644
--- a/check_api/src/main/java/com/google/errorprone/util/RuntimeVersion.java
+++ b/check_api/src/main/java/com/google/errorprone/util/RuntimeVersion.java
@@ -84,6 +84,11 @@ public static boolean isAtLeast22() {
     return FEATURE >= 22;
   }
 
+  /** Returns true if the current runtime is JDK 23 or newer. */
+  public static boolean isAtLeast23() {
+    return FEATURE >= 23;
+  }
+
   /**
    * Returns the latest {@code --release} version.
    *
diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/javadoc/Utils.java b/core/src/main/java/com/google/errorprone/bugpatterns/javadoc/Utils.java
index 1a81cf644787..0219c862da30 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/javadoc/Utils.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/javadoc/Utils.java
@@ -83,7 +83,7 @@ static SuggestedFix replace(DocTree docTree, String replacement, VisitorState st
     int startPos = getStartPosition(docTree, state);
     int endPos =
         (int) positions.getEndPosition(compilationUnitTree, getDocCommentTree(state), docTree);
-    if (endPos == Position.NOPOS) {
+    if (startPos == Position.NOPOS || endPos == Position.NOPOS) {
       return SuggestedFix.emptyFix();
     }
     return SuggestedFix.replace(startPos, endPos, replacement);
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/javadoc/InvalidLinkTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/javadoc/InvalidLinkTest.java
index 03cca7a05d5c..bad5c2775fda 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/javadoc/InvalidLinkTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/javadoc/InvalidLinkTest.java
@@ -17,9 +17,11 @@
 package com.google.errorprone.bugpatterns.javadoc;
 
 import static com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode.TEXT_MATCH;
+import static org.junit.Assume.assumeTrue;
 
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
 import com.google.errorprone.CompilationTestHelper;
+import com.google.errorprone.util.RuntimeVersion;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -181,4 +183,19 @@ public void emptyLinkTest() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void markdown() {
+    assumeTrue(RuntimeVersion.isAtLeast23());
+    helper
+        .addSourceLines(
+            "Test.java", //
+            "public class Test {",
+            "  /// Hello [bar]",
+            "  // BUG: Diagnostic contains: `bar` is a parameter",
+            "  static void foo(int bar) {}",
+            "}")
+        .setArgs("--release", "22")
+        .doTest();
+  }
 }