From a1413453288d91f7fecef4fcfb97402d341b217f Mon Sep 17 00:00:00 2001
From: Carter Kozak <ckozak@ckozak.net>
Date: Tue, 22 Sep 2020 09:41:58 -0400
Subject: [PATCH] fix #1498: Fix InvocationHandlerDelegation false positive
 (#1499)

fix #1498: Fix InvocationHandlerDelegation false positive
---
 .../InvocationHandlerDelegation.java          | 21 ++++++++++++++++++-
 .../InvocationHandlerDelegationTest.java      | 21 +++++++++++++++++++
 changelog/@unreleased/pr-1499.v2.yml          |  5 +++++
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 changelog/@unreleased/pr-1499.v2.yml

diff --git a/baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/InvocationHandlerDelegation.java b/baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/InvocationHandlerDelegation.java
index bcb272533..f0b1fe405 100644
--- a/baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/InvocationHandlerDelegation.java
+++ b/baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/InvocationHandlerDelegation.java
@@ -26,6 +26,10 @@
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.matchers.Matchers;
 import com.google.errorprone.matchers.method.MethodMatchers;
+import com.google.errorprone.predicates.TypePredicate;
+import com.google.errorprone.predicates.TypePredicates;
+import com.google.errorprone.predicates.type.DescendantOf;
+import com.google.errorprone.suppliers.Suppliers;
 import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.ConditionalExpressionTree;
 import com.sun.source.tree.ExpressionTree;
@@ -37,6 +41,7 @@
 import com.sun.source.tree.NewClassTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.TryTree;
+import com.sun.tools.javac.code.Type;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -83,8 +88,22 @@ public final class InvocationHandlerDelegation extends BugChecker implements Bug
     private static final Matcher<Tree> CONTAINS_UNWRAP_THROWABLE =
             Matchers.contains(ExpressionTree.class, UNWRAP_THROWABLE);
 
+    private static final TypePredicate IS_ITE_SUBTYPE =
+            new DescendantOf(Suppliers.typeFromClass(InvocationTargetException.class));
+
+    private static final TypePredicate IS_ITE_UNION = (TypePredicate) (type, state) -> {
+        if (type.isUnion()) {
+            for (Type unionType : MoreASTHelpers.expandUnion(type)) {
+                if (IS_ITE_SUBTYPE.apply(unionType, state)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    };
+
     private static final Matcher<ExpressionTree> UNWRAP_ITE = MethodMatchers.instanceMethod()
-            .onDescendantOf(InvocationTargetException.class.getName())
+            .onClass(TypePredicates.anyOf(IS_ITE_SUBTYPE, IS_ITE_UNION))
             // getTargetException is deprecated, but does work correctly.
             .namedAnyOf("getCause", "getTargetException")
             .withParameters();
diff --git a/baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/InvocationHandlerDelegationTest.java b/baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/InvocationHandlerDelegationTest.java
index 4e86976da..a133947b7 100644
--- a/baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/InvocationHandlerDelegationTest.java
+++ b/baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/InvocationHandlerDelegationTest.java
@@ -133,6 +133,27 @@ void testCorrectInvocationHandler_doesntRethrow() {
                 .doTest();
     }
 
+    @Test
+    void testInvocationHandler_catchUnion() {
+        helper().addSourceLines(
+                        "Test.java",
+                        "import java.lang.reflect.InvocationHandler;",
+                        "import java.lang.reflect.Method;",
+                        "import java.lang.reflect.InvocationTargetException;",
+                        "import java.lang.reflect.UndeclaredThrowableException;",
+                        "final class Test implements InvocationHandler {",
+                        "  @Override",
+                        "  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {",
+                        "    try {",
+                        "      return method.invoke(this, args);",
+                        "    } catch (InvocationTargetException | UndeclaredThrowableException e) {",
+                        "      throw e.getCause();",
+                        "    }",
+                        "  }",
+                        "}")
+                .doTest();
+    }
+
     @Test
     void testCorrectInvocationHandler_lambda() {
         helper().addSourceLines(
diff --git a/changelog/@unreleased/pr-1499.v2.yml b/changelog/@unreleased/pr-1499.v2.yml
new file mode 100644
index 000000000..ce9de86cd
--- /dev/null
+++ b/changelog/@unreleased/pr-1499.v2.yml
@@ -0,0 +1,5 @@
+type: fix
+fix:
+  description: Fix InvocationHandlerDelegation false positive
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/1499