Merge pull request #38135 from RikkiGibson/nested-generic-pointer

Give LangVersion error when type is generic due to parent type

src/Compilers/CSharp/Portable/Symbols/BaseTypeAnalysis.cs

@@ -220,8 +220,9 @@ private static (bool definitelyManaged, bool hasGenerics) DependsOnDefinitelyMan
         }
 
         /// <summary>
-        /// Returns a boolean value if we can determine whether the type is managed
-        /// without looking at its fields and Unset otherwise.
+        /// Returns True or False if we can determine whether the type is managed
+        /// without looking at its fields and Unknown otherwise.
+        /// Also returns whether or not the given type is generic.
         /// </summary>
         private static (ThreeState isManaged, bool hasGenerics) IsManagedTypeHelper(NamedTypeSymbol type)
         {
@@ -231,7 +232,7 @@ private static (ThreeState isManaged, bool hasGenerics) IsManagedTypeHelper(Name
                 type = type.GetEnumUnderlyingType();
             }
 
-            bool hasGenerics = type.TupleUnderlyingTypeOrSelf().GetArity() > 0;
+            bool hasGenerics = type.TupleUnderlyingTypeOrSelf() is NamedTypeSymbol { IsGenericType: true };
 
             // Short-circuit common cases.
             switch (type.SpecialType)

src/Compilers/CSharp/Test/Semantic/Semantics/GenericConstraintsTests.cs

@@ -3938,6 +3938,33 @@ public unsafe struct OtherStruct
             CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
         }
 
+        [Fact]
+        public void GenericNestedStructPointerFieldRequiresCSharp8()
+        {
+            var code = @"
+public struct MyStruct<T>
+{
+    public struct InnerStruct
+    {
+        public T field;
+    }
+}
+
+public unsafe struct OtherStruct
+{
+    public MyStruct<int>.InnerStruct* ms;
+}
+";
+            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll, parseOptions: TestOptions.Regular7_3)
+                .VerifyDiagnostics(
+                    // (12,39): error CS8370: Feature 'unmanaged constructed types' is not available in C# 7.3. Please use language version 8.0 or greater.
+                    //     public MyStruct<int>.InnerStruct* ms;
+                    Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "ms").WithArguments("unmanaged constructed types", "8.0").WithLocation(12, 39)
+                );
+
+            CreateCompilation(code, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics();
+        }
+
         [Fact, WorkItem(32103, "https://github.com/dotnet/roslyn/issues/32103")]
         public void StructContainingTuple_Unmanaged_RequiresCSharp8()
         {

src/Compilers/CSharp/Test/Semantic/Semantics/UnsafeTests.cs

@@ -2715,11 +2715,14 @@ class C<U>
     S<int> f2;
     S<U>.R f3;
     S<int>.R f4;
+    S<U>.R2 f5;
+    S<int>.R2 f6;
 }
 
 struct S<T>
 {
     struct R { }
+    internal struct R2 { }
 }
 ";
             var compilation = CreateCompilation(text);
@@ -2734,6 +2737,11 @@ struct R { }
             Assert.Equal(ManagedKind.Managed, type.GetMember<FieldSymbol>("f3").Type.ManagedKind);
             Assert.True(type.GetMember<FieldSymbol>("f4").Type.IsManagedType);
             Assert.Equal(ManagedKind.Managed, type.GetMember<FieldSymbol>("f4").Type.ManagedKind);
+
+            Assert.False(type.GetMember<FieldSymbol>("f5").Type.IsManagedType);
+            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f5").Type.ManagedKind);
+            Assert.False(type.GetMember<FieldSymbol>("f6").Type.IsManagedType);
+            Assert.Equal(ManagedKind.UnmanagedWithGenerics, type.GetMember<FieldSymbol>("f6").Type.ManagedKind);
         }
 
         [Fact]