From 41acf0bd49684e84a67f3b7e7a75e5d9a0a9fc06 Mon Sep 17 00:00:00 2001
From: Demian Banakh <dembanakh01@gmail.com>
Date: Thu, 26 Jan 2023 22:19:49 +0100
Subject: [PATCH] Allow calling extension methods on `this` as receiver

---
 AUTHORS                                       |  1 +
 .../javac/handlers/HandleExtensionMethod.java |  7 ++++++-
 .../after-delombok/ExtensionMethodThis.java   | 14 ++++++++++++++
 .../after-ecj/ExtensionMethodThis.java        | 19 +++++++++++++++++++
 .../resource/before/ExtensionMethodThis.java  | 17 +++++++++++++++++
 5 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 test/transform/resource/after-delombok/ExtensionMethodThis.java
 create mode 100644 test/transform/resource/after-ecj/ExtensionMethodThis.java
 create mode 100644 test/transform/resource/before/ExtensionMethodThis.java

diff --git a/AUTHORS b/AUTHORS
index 50f9e10eec..736e955531 100755
--- a/AUTHORS
+++ b/AUTHORS
@@ -13,6 +13,7 @@ Christoph Dreis <christoph.dreis@freenet.de>
 DaveLaw <project.lombok@apconsult.de>
 Dave Brosius <dbrosius@mebigfatguy.com>
 Dawid Rusin <dawidrusin90@gmail.com>
+Demian Banakh <dembanakh01@gmail.com>
 Denis Stepanov <denis.stepanov@gmail.com>
 Emil Lundberg <emil@yubico.com>
 Enrique da Costa Cambio <enrique.dacostacambio@gmail.com>
diff --git a/src/core/lombok/javac/handlers/HandleExtensionMethod.java b/src/core/lombok/javac/handlers/HandleExtensionMethod.java
index af03d00085..58e9ce3412 100644
--- a/src/core/lombok/javac/handlers/HandleExtensionMethod.java
+++ b/src/core/lombok/javac/handlers/HandleExtensionMethod.java
@@ -171,7 +171,8 @@ private void handleMethodCall(final JCMethodInvocation methodCall) {
 			JCExpression receiver = receiverOf(methodCall);
 			String methodName = methodNameOf(methodCall);
 			
-			if ("this".equals(receiver.toString()) || "this".equals(methodName) || "super".equals(methodName)) return;
+			if ("this".equals(receiver.toString()) && isImplicitReceiver(methodCall)) return;
+			if ("this".equals(methodName) || "super".equals(methodName)) return;
 			Map<JCTree, JCTree> resolution = new JavacResolution(methodCallNode.getContext()).resolveMethodMember(methodCallNode);
 			
 			JCTree resolvedMethodCall = resolution.get(methodCall);
@@ -224,5 +225,9 @@ private JCExpression receiverOf(final JCMethodInvocation methodCall) {
 				return ((JCFieldAccess) methodCall.meth).selected;
 			}
 		}
+		
+		private boolean isImplicitReceiver(final JCMethodInvocation methodCall) {
+			return methodCall.meth instanceof JCIdent;
+		}
 	}
 }
diff --git a/test/transform/resource/after-delombok/ExtensionMethodThis.java b/test/transform/resource/after-delombok/ExtensionMethodThis.java
new file mode 100644
index 0000000000..be49af1aa4
--- /dev/null
+++ b/test/transform/resource/after-delombok/ExtensionMethodThis.java
@@ -0,0 +1,14 @@
+class ExtensionMethodThis {
+	public void test() {
+		ExtensionMethodThis.Extensions.hello(this);
+		hello();
+	}
+	
+	private void hello() {
+	}
+	
+	static class Extensions {
+		public static void hello(ExtensionMethodThis self) {	
+		}
+	}
+}
diff --git a/test/transform/resource/after-ecj/ExtensionMethodThis.java b/test/transform/resource/after-ecj/ExtensionMethodThis.java
new file mode 100644
index 0000000000..93df61d454
--- /dev/null
+++ b/test/transform/resource/after-ecj/ExtensionMethodThis.java
@@ -0,0 +1,19 @@
+import lombok.experimental.ExtensionMethod;
+@ExtensionMethod(ExtensionMethodThis.Extensions.class) class ExtensionMethodThis {
+  static class Extensions {
+    Extensions() {
+      super();
+    }
+    public static void hello(ExtensionMethodThis self) {
+    }
+  }
+  ExtensionMethodThis() {
+    super();
+  }
+  public void test() {
+    ExtensionMethodThis.Extensions.hello(this);
+    hello();
+  }
+  private void hello() {
+  }
+}
diff --git a/test/transform/resource/before/ExtensionMethodThis.java b/test/transform/resource/before/ExtensionMethodThis.java
new file mode 100644
index 0000000000..7f66a08a9d
--- /dev/null
+++ b/test/transform/resource/before/ExtensionMethodThis.java
@@ -0,0 +1,17 @@
+import lombok.experimental.ExtensionMethod;
+
+@ExtensionMethod(ExtensionMethodThis.Extensions.class)
+class ExtensionMethodThis {
+	public void test() {
+		this.hello();
+		hello();
+	}
+	
+	private void hello() {
+	}
+	
+	static class Extensions {
+		public static void hello(ExtensionMethodThis self) {
+		}
+	}
+}