From 3a4b8a428f8a4b35de852abb72dd0cede3c399da Mon Sep 17 00:00:00 2001
From: Srikanth Sankaran <131454720+srikanth-sankaran@users.noreply.github.com>
Date: Wed, 6 Mar 2024 20:19:07 +0530
Subject: [PATCH] Apply the boxing conversion post instanceof where required
 (#2105)

* Fixes https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2104
---
 .../compiler/ast/InstanceOfExpression.java    |  9 ++++--
 .../regression/PatternMatching16Test.java     | 28 +++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/InstanceOfExpression.java b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/InstanceOfExpression.java
index 08f0a91435c..06972fc1fbc 100644
--- a/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/InstanceOfExpression.java
+++ b/org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/InstanceOfExpression.java
@@ -128,9 +128,14 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean
 			codeStream.iconst_0();
 
 		continueLabel.place();
-	} else if (!valueRequired) {
-		codeStream.pop();
 	}
+
+	if (valueRequired) {
+		codeStream.generateImplicitConversion(this.implicitConversion);
+	} else if (this.pattern == null) {
+		codeStream.pop(); // in the pattern case, if (!valueRequired), we have nothing on the stack to pop
+	}
+
 	codeStream.recordPositionsFrom(codeStream.position, this.sourceEnd);
 }
 
diff --git a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/PatternMatching16Test.java b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/PatternMatching16Test.java
index faf060c541b..9c9ad554257 100644
--- a/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/PatternMatching16Test.java
+++ b/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/PatternMatching16Test.java
@@ -4812,4 +4812,32 @@ public static void main(String [] args) {
 				"for\n"
 				+ "!for");
 	}
+	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2104
+	// [Patterns] Missing boxing conversion after instanceof leads to verify error
+	public void testBoxing() {
+		runConformTest(
+				new String[] {
+						"X.java",
+						"""
+						public class X {
+
+							public static void foo(Boolean b) {
+								System.out.println(b);
+							}
+
+							public static void main(String [] args) {
+								Object o = new Object();
+								foo(o instanceof String);
+								foo("Hello" instanceof String);
+								foo(o instanceof String s);
+								foo("Hello" instanceof String s);
+							}
+						}
+						""",
+				},
+				"false\n"
+				+ "true\n"
+				+ "false\n"
+				+ "true");
+	}
 }