From ca6d987c56375908c62eec7c8819c62db8acd489 Mon Sep 17 00:00:00 2001
From: Sam Brannen <104798+sbrannen@users.noreply.github.com>
Date: Tue, 23 Apr 2024 11:34:18 +0300
Subject: [PATCH] Support compilation of array and list indexing with Integer
 in SpEL

Prior to this commit, the Spring Expression Language (SpEL) failed to
compile an expression that indexed into any array or list using an
Integer.

This commit adds support for compilation of such expressions by
ensuring that an Integer is unboxed into an int in the compiled
bytecode.

Closes gh-32694
---
 .../expression/spel/ast/Indexer.java          |  9 +++++--
 .../spel/SpelCompilationCoverageTests.java    | 26 +++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java b/spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java
index be10fbfed3..f3ba081fda 100644
--- a/spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java
+++ b/spring-expression/src/main/java/org/springframework/expression/spel/ast/Indexer.java
@@ -416,13 +416,13 @@ public class Indexer extends SpelNodeImpl {
 				default -> AALOAD;
 			};
 
-			generateIndexCode(index, mv, cf);
+			generateIndexCode(index, int.class, mv, cf);
 			mv.visitInsn(insn);
 		}
 
 		else if (this.indexedType == IndexedType.LIST) {
 			mv.visitTypeInsn(CHECKCAST, "java/util/List");
-			generateIndexCode(index, mv, cf);
+			generateIndexCode(index, int.class, mv, cf);
 			mv.visitMethodInsn(INVOKEINTERFACE, "java/util/List", "get", "(I)Ljava/lang/Object;", true);
 		}
 
@@ -473,6 +473,11 @@ public class Indexer extends SpelNodeImpl {
 		cf.exitCompilationScope();
 	}
 
+	private void generateIndexCode(SpelNodeImpl indexNode, Class<?> indexType, MethodVisitor mv, CodeFlow cf) {
+		String indexDesc = CodeFlow.toDescriptor(indexType);
+		generateCodeForArgument(mv, cf, indexNode, indexDesc);
+	}
+
 	@Override
 	public String toStringAST() {
 		return "[" + getChild(0).toStringAST() + "]";
diff --git a/spring-expression/src/test/java/org/springframework/expression/spel/SpelCompilationCoverageTests.java b/spring-expression/src/test/java/org/springframework/expression/spel/SpelCompilationCoverageTests.java
index 77da11dea1..e5a7b3692b 100644
--- a/spring-expression/src/test/java/org/springframework/expression/spel/SpelCompilationCoverageTests.java
+++ b/spring-expression/src/test/java/org/springframework/expression/spel/SpelCompilationCoverageTests.java
@@ -706,6 +706,32 @@ public class SpelCompilationCoverageTests extends AbstractExpressionTests {
 			assertThat(getAst().getExitDescriptor()).isEqualTo("Ljava/lang/String");
 		}
 
+		@Test  // gh-32694
+		void indexIntoArrayUsingIntegerWrapper() {
+			context.setVariable("array", new int[] {1, 2, 3, 4});
+			context.setVariable("index", 2);
+
+			expression = parser.parseExpression("#array[#index]");
+
+			assertThat(expression.getValue(context)).isEqualTo(3);
+			assertCanCompile(expression);
+			assertThat(expression.getValue(context)).isEqualTo(3);
+			assertThat(getAst().getExitDescriptor()).isEqualTo("I");
+		}
+
+		@Test  // gh-32694
+		void indexIntoListUsingIntegerWrapper() {
+			context.setVariable("list", List.of(1, 2, 3, 4));
+			context.setVariable("index", 2);
+
+			expression = parser.parseExpression("#list[#index]");
+
+			assertThat(expression.getValue(context)).isEqualTo(3);
+			assertCanCompile(expression);
+			assertThat(expression.getValue(context)).isEqualTo(3);
+			assertThat(getAst().getExitDescriptor()).isEqualTo("Ljava/lang/Object");
+		}
+
 		private String stringify(Object object) {
 			Stream<? extends Object> stream;
 			if (object instanceof Collection<?> collection) {