From ac1fb3434233e8f2c707a40ec979153406b94f8f Mon Sep 17 00:00:00 2001
From: GBNikola <GBNikola@users.noreply.github.com>
Date: Mon, 10 Aug 2026 14:54:50 +0200
Subject: [PATCH] AVRO-4331: [csharp] Fix unreachable code in generated
 Get()/Put()

avrogen built the Get()/Put() switch body via CodeSnippetExpression,
which CodeDom wraps in a CodeExpressionStatement and always suffixes
with a ";". Since every switch arm returns or throws, that trailing
";" is unreachable. Roslyn stays quiet about it, but IDE analyzers
with fuller flow analysis (ReSharper/Rider) flag it, forcing
consumers to suppress CS0162 for all avrogen output.

Use CodeSnippetStatement instead, which emits the block verbatim
with no appended semicolon.
---
 .../csharp/src/apache/main/CodeGen/CodeGen.cs |  8 +++---
 .../src/apache/test/CodGen/CodeGenTest.cs     | 26 +++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/lang/csharp/src/apache/main/CodeGen/CodeGen.cs b/lang/csharp/src/apache/main/CodeGen/CodeGen.cs
index 73b95852d7b..36c83a98496 100644
--- a/lang/csharp/src/apache/main/CodeGen/CodeGen.cs
+++ b/lang/csharp/src/apache/main/CodeGen/CodeGen.cs
@@ -874,15 +874,15 @@ protected virtual CodeTypeDeclaration processRecord(Schema schema)
             // end switch block for Get()
             getFieldStmt.AppendLine("\t\t\tdefault: throw new global::Avro.AvroRuntimeException(\"Bad index \" + fieldPos + \" in Get()\");")
                 .Append("\t\t\t}");
-            var cseGet = new CodeSnippetExpression(getFieldStmt.ToString());
-            cmmGet.Statements.Add(cseGet);
+            var cssGet = new CodeSnippetStatement(getFieldStmt.ToString());
+            cmmGet.Statements.Add(cssGet);
             ctd.Members.Add(cmmGet);
 
             // end switch block for Put()
             putFieldStmt.AppendLine("\t\t\tdefault: throw new global::Avro.AvroRuntimeException(\"Bad index \" + fieldPos + \" in Put()\");")
                 .Append("\t\t\t}");
-            var csePut = new CodeSnippetExpression(putFieldStmt.ToString());
-            cmmPut.Statements.Add(csePut);
+            var cssPut = new CodeSnippetStatement(putFieldStmt.ToString());
+            cmmPut.Statements.Add(cssPut);
             ctd.Members.Add(cmmPut);
 
             string nspace = recordSchema.Namespace;
diff --git a/lang/csharp/src/apache/test/CodGen/CodeGenTest.cs b/lang/csharp/src/apache/test/CodGen/CodeGenTest.cs
index 33c7f0cf6ee..f10f11df8dd 100644
--- a/lang/csharp/src/apache/test/CodGen/CodeGenTest.cs
+++ b/lang/csharp/src/apache/test/CodGen/CodeGenTest.cs
@@ -110,6 +110,32 @@ public void GetTypesShouldReturnTypes()
                 Assert.That(Regex.Matches(planetEnumCode, "public enum PlanetEnum").Count, Is.EqualTo(1));
             }
 
+            [Test]
+            public void RecordGetAndPutSwitchesShouldNotEmitUnreachableStatement()
+            {
+                AddSchema(@"
+{
+  ""name"": ""Sample"",
+  ""namespace"": ""Avro.Test.CodeGen.UnreachableCodeRegression"",
+  ""type"": ""record"",
+  ""fields"": [
+    { ""name"": ""value"", ""type"": ""string"" }
+  ]
+}
+");
+                GenerateCode();
+                var types = GetTypes();
+                bool hasSampleCode = types.TryGetValue("Sample", out string sampleCode);
+                Assert.That(hasSampleCode);
+
+                // The exhaustive switch in Get()/Put() must not be followed by a stray ";" -
+                // that empty statement is unreachable (every case returns or throws) and
+                // trips IDE-only unreachable-code analysis (e.g. ReSharper) even though Roslyn
+                // does not flag it.
+                Assert.That(Regex.IsMatch(sampleCode, @"\}\s*;\s*\}\s*public virtual void Put"), Is.False);
+                Assert.That(Regex.IsMatch(sampleCode, @"in Put\(\)""\);\s*\}\s*;"), Is.False);
+            }
+
             [Test]
             public void EnumWithKeywordSymbolsShouldHavePrefixedSymbols()
             {