From 417785a2bee94a9cf2807a14f72d2ae24a3548dc Mon Sep 17 00:00:00 2001
From: AlekseyTs <AlekseyTs@users.noreply.github.com>
Date: Mon, 5 Jun 2023 08:00:50 -0700
Subject: [PATCH] `makeNotNullMembersMaybeNull` - skip primary constructor
 capture fields

Fixes #68384.
---
 .../Portable/FlowAnalysis/NullableWalker.cs   |  3 +
 .../Semantics/PrimaryConstructorTests.cs      | 67 +++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs b/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs
index 071424a5d9935..eeda541534b67 100644
--- a/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs
+++ b/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs
@@ -883,6 +883,9 @@ void makeNotNullMembersMaybeNull()
                                 case PropertySymbol:
                                     // skip any manually implemented non-required properties.
                                     continue;
+                                case FieldSymbol { OriginalDefinition: SynthesizedPrimaryConstructorParameterBackingFieldSymbol }:
+                                    // Skip primary constructor capture fields, compiler initializes them with parameters' values
+                                    continue;
                                 case FieldSymbol { IsConst: true }:
                                     continue;
                                 case FieldSymbol { AssociatedSymbol: PropertySymbol prop }:
diff --git a/src/Compilers/CSharp/Test/Semantic/Semantics/PrimaryConstructorTests.cs b/src/Compilers/CSharp/Test/Semantic/Semantics/PrimaryConstructorTests.cs
index e3905450d2eff..e3e15050ed716 100644
--- a/src/Compilers/CSharp/Test/Semantic/Semantics/PrimaryConstructorTests.cs
+++ b/src/Compilers/CSharp/Test/Semantic/Semantics/PrimaryConstructorTests.cs
@@ -15389,6 +15389,73 @@ .property instance int32 P2()
 ".Replace("[mscorlib]", ExecutionConditionUtil.IsDesktop ? "[mscorlib]" : "[netstandard]"));
         }
 
+        [Fact]
+        [WorkItem("https://github.com/dotnet/roslyn/issues/68384")]
+        public void ParameterCapturing_152_NullableAnalysis()
+        {
+            var source = @"
+#nullable enable
+
+class B(string s)
+{
+    public string S { get; } = s;
+}
+
+class C(B b)
+    : B(b.S)
+{
+    string T() => b.S;
+}";
+            var comp = CreateCompilation(source, options: TestOptions.ReleaseDll);
+            comp.VerifyDiagnostics();
+        }
+
+        [Fact]
+        [WorkItem("https://github.com/dotnet/roslyn/issues/68384")]
+        public void ParameterCapturing_153_NullableAnalysis()
+        {
+            var source = @"
+#nullable enable
+
+class B(System.Func<string> s)
+{
+    public string S { get; } = s();
+}
+
+class C(B b)
+    : B(() => b.S)
+{
+    string T() => b.S;
+}";
+            var comp = CreateCompilation(source, options: TestOptions.ReleaseDll);
+            comp.VerifyDiagnostics();
+        }
+
+        [Fact]
+        [WorkItem("https://github.com/dotnet/roslyn/issues/68384")]
+        public void ParameterCapturing_154_NullableAnalysis()
+        {
+            var source = @"
+#nullable enable
+
+class B(System.Func<string> s)
+{
+    public string S { get; } = s();
+}
+
+class C(B b)
+    : B(() =>
+        {
+            string local() => b.S;
+            return local();
+        })
+{
+    string T() => b.S;
+}";
+            var comp = CreateCompilation(source, options: TestOptions.ReleaseDll);
+            comp.VerifyDiagnostics();
+        }
+
         [Fact]
         public void CycleDueToIndexerNameAttribute_01()
         {