From affa37ac76a9bd726e46ad6108a707436fdfeded Mon Sep 17 00:00:00 2001
From: ghm <ghm@google.com>
Date: Thu, 14 Dec 2023 04:37:27 -0800
Subject: [PATCH] Do not flag unused parameters on _abstract_ methods.

I think this was introduced in https://github.com/google/error-prone/commit/88a224c9f00deca8757fd864a8d29941cff1ac12, where we suddenly start considering some _effectively_ private abstract methods.

PiperOrigin-RevId: 590895990
---
 .../java/com/google/errorprone/bugpatterns/UnusedVariable.java | 3 ++-
 .../com/google/errorprone/bugpatterns/UnusedVariableTest.java  | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/UnusedVariable.java b/core/src/main/java/com/google/errorprone/bugpatterns/UnusedVariable.java
index 4622c14cae5..8f2955ad0f6 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/UnusedVariable.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/UnusedVariable.java
@@ -706,7 +706,8 @@ private boolean isParameterSubjectToAnalysis(Symbol sym) {
       checkArgument(sym.getKind() == ElementKind.PARAMETER);
       Symbol enclosingMethod = sym.owner;
 
-      if (!(enclosingMethod instanceof MethodSymbol)) {
+      if (!(enclosingMethod instanceof MethodSymbol)
+          || isAbstract((MethodSymbol) enclosingMethod)) {
         return false;
       }
 
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/UnusedVariableTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/UnusedVariableTest.java
index 76ccd5999b8..79da2f90e8f 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/UnusedVariableTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/UnusedVariableTest.java
@@ -263,6 +263,9 @@ public void unusedParamInPrivateMethod() {
             "      System.out.println(i);",
             "    }",
             "  }",
+            "  private interface Foo {",
+            "    void foo(int a);",
+            "  }",
             "  public void main() {",
             "    test(1, 2);",
             "  }",