From 721096fd16b9f9af7ae7dd657bd9d4ae75db5b46 Mon Sep 17 00:00:00 2001
From: Liam Miller-Cushon <cushon@google.com>
Date: Fri, 30 Dec 2022 17:04:58 -0800
Subject: [PATCH] Fix a crash in NonCanonicalType on module symbols

Fixes https://github.com/google/error-prone/issues/3639

PiperOrigin-RevId: 498646740
---
 .../errorprone/bugpatterns/NonCanonicalType.java     |  7 ++++++-
 .../errorprone/bugpatterns/NonCanonicalTypeTest.java | 12 ++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/NonCanonicalType.java b/core/src/main/java/com/google/errorprone/bugpatterns/NonCanonicalType.java
index bfe848bba12..0991a851a59 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/NonCanonicalType.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/NonCanonicalType.java
@@ -89,7 +89,12 @@ private static String canonicalName(MemberSelectTree tree) {
     if (!(sym instanceof Symbol.TypeSymbol)) {
       return null;
     }
-    return sym.owner.getQualifiedName() + "." + sym.getSimpleName();
+    Symbol owner = sym.owner;
+    if (owner == null) {
+      // module symbols don't have owners
+      return null;
+    }
+    return owner.getQualifiedName() + "." + sym.getSimpleName();
   }
 
   private static final Pattern PACKAGE_CLASS_NAME_SPLITTER = Pattern.compile("(.*?)\\.([A-Z].*)");
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/NonCanonicalTypeTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/NonCanonicalTypeTest.java
index 127bca95cc5..23d1d6e8ab6 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/NonCanonicalTypeTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/NonCanonicalTypeTest.java
@@ -242,4 +242,16 @@ public void innerArray() {
             "}")
         .doTest();
   }
+
+  // see https://github.com/google/error-prone/issues/3639
+  @Test
+  public void moduleInfo() {
+    compilationHelper
+        .addSourceLines(
+            "module-info.java", //
+            "module testmodule {",
+            "  requires java.base;",
+            "}")
+        .doTest();
+  }
 }