From b9c272faabfa50a6397626214c97800a7de7ffc4 Mon Sep 17 00:00:00 2001
From: ghm <ghm@google.com>
Date: Fri, 17 Jan 2025 07:05:26 -0800
Subject: [PATCH] PatternMatchingInstanceof: handle ternaries.

How'd I forget them?

PiperOrigin-RevId: 716655410
---
 .../PatternMatchingInstanceof.java            |  9 +++
 .../PatternMatchingInstanceofTest.java        | 56 +++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceof.java b/core/src/main/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceof.java
index f9bf9062b91..ee6feb5626d 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceof.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceof.java
@@ -35,6 +35,7 @@
 import com.sun.source.tree.AssignmentTree;
 import com.sun.source.tree.BinaryTree;
 import com.sun.source.tree.BlockTree;
+import com.sun.source.tree.ConditionalExpressionTree;
 import com.sun.source.tree.IfTree;
 import com.sun.source.tree.InstanceOfTree;
 import com.sun.source.tree.ParenthesizedTree;
@@ -194,6 +195,14 @@ private static ImmutableList<Tree> findImpliedStatements(
           }
           return impliedStatements.build();
         }
+        case CONDITIONAL_EXPRESSION -> {
+          var conditionalExpression = (ConditionalExpressionTree) parent;
+          impliedStatements.add(
+              negated
+                  ? conditionalExpression.getFalseExpression()
+                  : conditionalExpression.getTrueExpression());
+          return impliedStatements.build();
+        }
         default -> {
           return impliedStatements.build();
         }
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceofTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceofTest.java
index c5fb75b4c41..3357e4082a2 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceofTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceofTest.java
@@ -591,4 +591,60 @@ public boolean equals(Object o) {
             """)
         .doTest();
   }
+
+  @Test
+  public void conditionalExpression() {
+    helper
+        .addInputLines(
+            "Test.java",
+            """
+            class Test {
+              private String val;
+
+              public String stringify(Object o) {
+                return o instanceof Test ? ((Test) o).val : "not a test";
+              }
+            }
+            """)
+        .addOutputLines(
+            "Test.java",
+            """
+            class Test {
+              private String val;
+
+              public String stringify(Object o) {
+                return o instanceof Test test ? test.val : "not a test";
+              }
+            }
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void conditionalExpression_negated() {
+    helper
+        .addInputLines(
+            "Test.java",
+            """
+            class Test {
+              private String val;
+
+              public String stringify(Object o) {
+                return !(o instanceof Test) ? "not a test" : ((Test) o).val;
+              }
+            }
+            """)
+        .addOutputLines(
+            "Test.java",
+            """
+            class Test {
+              private String val;
+
+              public String stringify(Object o) {
+                return !(o instanceof Test test) ? "not a test" : test.val;
+              }
+            }
+            """)
+        .doTest();
+  }
 }