From 7750b9a8d69228ee281fdda89cd9afee8cf98113 Mon Sep 17 00:00:00 2001
From: dudik <dudi.keleti@gmail.com>
Date: Wed, 19 Nov 2025 14:36:13 +0100
Subject: [PATCH 1/2] Convert return expression when expression type is
 assignable to T but different (e.g., value type -> object)

---
 .../Debugger/Expressions/ProbeExpressionParser.cs      | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.cs b/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.cs
index 7ba6694b31d2..e935599f8cea 100644
--- a/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.cs
+++ b/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.cs
@@ -441,7 +441,15 @@ private Expression HandleReturnType(Expression finalExpr, List<ParameterExpressi
     {
         if (typeof(T).IsAssignableFrom(finalExpr.Type))
         {
-            return finalExpr;
+            // If the expression type is already exactly T, return as-is.
+            if (finalExpr.Type == typeof(T))
+            {
+                return finalExpr;
+            }
+
+            // When the expression type is assignable to T but different (e.g., value type -> object),
+            // we need an explicit conversion.
+            return Expression.Convert(finalExpr, typeof(T));
         }
 
         if (typeof(T).IsNumeric()

From 854987a213b37dcd8dcdff28c75735871226433b Mon Sep 17 00:00:00 2001
From: dudik <dudi.keleti@gmail.com>
Date: Wed, 19 Nov 2025 14:58:50 +0100
Subject: [PATCH 2/2] add test that reproduce the issue

---
 .../DebuggerExpressionLanguageTests.cs        | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tracer/test/Datadog.Trace.Tests/Debugger/DebuggerExpressionLanguageTests.cs b/tracer/test/Datadog.Trace.Tests/Debugger/DebuggerExpressionLanguageTests.cs
index 13af04659172..c41299dc44b8 100644
--- a/tracer/test/Datadog.Trace.Tests/Debugger/DebuggerExpressionLanguageTests.cs
+++ b/tracer/test/Datadog.Trace.Tests/Debugger/DebuggerExpressionLanguageTests.cs
@@ -111,6 +111,32 @@ public async Task TestMetrics(string expressionTestFilePath)
             await Test(expressionTestFilePath);
         }
 
+        [Fact]
+        public void ProbeExpressionParser_ObjectReturnType_AllowsValueTypeResults()
+        {
+            // Arrange
+            var scopeMembers = CreateScopeMembers();
+            const string json = """
+                                {
+                                  "ref": "@duration"
+                                }
+                                """;
+
+            // Act
+            var compiled = ProbeExpressionParser<object>.ParseExpression(json, scopeMembers);
+            var result = compiled.Delegate(
+                scopeMembers.InvocationTarget,
+                scopeMembers.Return,
+                scopeMembers.Duration,
+                scopeMembers.Exception,
+                scopeMembers.Members);
+
+            // Assert
+            Assert.NotNull(result);
+            Assert.IsType<TimeSpan>(result);
+            Assert.True(compiled.Errors == null || compiled.Errors.Length == 0);
+        }
+
         private async Task Test(string expressionTestFilePath)
         {
             // Arrange