From 2214aa04511d88df14ca32f753c7c614343b786f Mon Sep 17 00:00:00 2001
From: Layomi Akinrinade <laakinri@microsoft.com>
Date: Fri, 7 Jan 2022 01:39:46 -0500
Subject: [PATCH] Suppress warnings about [Obsolete] member usage in JSON
 src-gen'd code

---
 .../gen/JsonSourceGenerator.Emitter.cs        |  5 ++-
 .../JsonSourceGeneratorTests.cs               | 31 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs b/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs
index 2a8e805499fd67..aa7404066fe22f 100644
--- a/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs
+++ b/src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs
@@ -146,7 +146,10 @@ private void AddSource(string fileName, string source, bool isRootContextDef = f
                 bool isInGlobalNamespace = @namespace == JsonConstants.GlobalNamespaceValue;
 
                 StringBuilder sb = new(@"// <auto-generated/>
-#nullable enable");
+#nullable enable
+
+// Suppress warnings about [Obsolete] member usage in generated code.
+#pragma warning disable CS0618");
 
                 if (!isInGlobalNamespace)
                 {
diff --git a/src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Unit.Tests/JsonSourceGeneratorTests.cs b/src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Unit.Tests/JsonSourceGeneratorTests.cs
index 2cb749bb40bc69..ca6b835f38170b 100644
--- a/src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Unit.Tests/JsonSourceGeneratorTests.cs
+++ b/src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Unit.Tests/JsonSourceGeneratorTests.cs
@@ -522,5 +522,36 @@ public class MyType
             Assert.Equal(1, types.Count);
             Assert.Equal("HelloWorld.MyType", types.Keys.First());
         }
+
+        [Fact]
+        public static void NoWarningsDueToObsoleteMembers()
+        {
+                string source = @"using System;
+using System.Text.Json.Serialization;
+
+namespace Test
+{
+    [JsonSerializable(typeof(ClassWithObsolete))]
+    public partial class JsonContext : JsonSerializerContext { }
+
+    public class ClassWithObsolete
+    {
+        [Obsolete(""This is a test"")]
+        public bool Test { get; set; }
+    }
+}
+";
+
+            Compilation compilation = CompilationHelper.CreateCompilation(source);
+            JsonSourceGenerator generator = new JsonSourceGenerator();
+
+            Compilation newCompilation = CompilationHelper.RunGenerators(compilation, out _, generator);
+            ImmutableArray<Diagnostic> generatorDiags = newCompilation.GetDiagnostics();
+
+            // No diagnostics expected.
+            CompilationHelper.CheckDiagnosticMessages(DiagnosticSeverity.Info, generatorDiags, Array.Empty<(Location, string)>());
+            CompilationHelper.CheckDiagnosticMessages(DiagnosticSeverity.Warning, generatorDiags, Array.Empty<(Location, string)>());
+            CompilationHelper.CheckDiagnosticMessages(DiagnosticSeverity.Error, generatorDiags, Array.Empty<(Location, string)>());
+        }
     }
 }