C#: Adds version 8 and expands nullability to reference types (#1632)

.github/workflows/test-pr.yaml

@@ -123,7 +123,7 @@ jobs:
               if: ${{ contains(matrix.fixture, 'csharp') }}
               uses: actions/setup-dotnet@v3
               with:
-                  dotnet-version: 6
+                  dotnet-version: 8
 
             - name: Install Rust
               if: ${{ contains(matrix.fixture, 'rust') }}

packages/quicktype-core/src/language/CSharp/CSharpRenderer.ts

@@ -188,7 +188,7 @@ export class CSharpRenderer extends ConvenienceRenderer {
     ): Sourcelike {
         t = followTargetType(t);
         const csType = this.csType(t, follow, withIssues);
-        if (isValueType(t)) {
+        if (isValueType(t) || this._csOptions.version >= 8) {
             return [csType, "?"];
         } else {
             return csType;

packages/quicktype-core/src/language/CSharp/NewtonSoftCSharpRenderer.ts

@@ -192,6 +192,15 @@ export class NewtonsoftCSharpRenderer extends CSharpRenderer {
         return this._options.baseclass;
     }
 
+    protected emitDefaultFollowingComments(): void {
+        if (!this._needHelpers || this._options.version < 8) return;
+
+        this.emitLine("#pragma warning restore CS8618");
+        this.emitLine("#pragma warning restore CS8601");
+        this.emitLine("#pragma warning restore CS8603");
+        this.emitLine("#pragma warning restore CS8765");
+    }
+
     protected emitDefaultLeadingComments(): void {
         if (!this._needHelpers) return;
 
@@ -225,6 +234,14 @@ export class NewtonsoftCSharpRenderer extends CSharpRenderer {
                 ";",
             );
         });
+
+        if (this._options.version >= 8) {
+            this.emitLine("#nullable enable");
+            this.emitLine("#pragma warning disable CS8618");
+            this.emitLine("#pragma warning disable CS8601");
+            this.emitLine("#pragma warning disable CS8603");
+            this.emitLine("#pragma warning disable CS8765");
+        }
     }
 
     private converterForType(t: Type): Name | undefined {

packages/quicktype-core/src/language/CSharp/SystemTextJsonCSharpRenderer.ts

@@ -275,6 +275,13 @@ export class SystemTextJsonCSharpRenderer extends CSharpRenderer {
         const isNullable = followTargetType(property.type).isNullable;
         const isOptional = property.isOptional;
 
+        // [JsonRequired] makes deserialization fail if the property is
+        // missing from the JSON.  It requires System.Text.Json 7.0 or
+        // later (.NET 7+).
+        if (this._options.checkRequired && !isOptional) {
+            attributes.push(["[JsonRequired]"]);
+        }
+
         if (isOptional && !isNullable) {
             attributes.push([
                 "[",

packages/quicktype-core/src/language/CSharp/language.ts

@@ -69,6 +69,7 @@ export const cSharpOptions = {
         {
             "5": 5,
             "6": 6,
+            "8": 8,
         } as const,
         "6",
         "secondary",

test/fixtures/csharp-SystemTextJson/test.csproj

@@ -1,9 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="System.Text.Json" Version="6.0.10" />
+    <PackageReference Include="System.Text.Json" Version="8.0.5" />
   </ItemGroup>
 </Project>

test/fixtures/csharp/test.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp6.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />

test/languages.ts

@@ -118,6 +118,7 @@ export const CSharpLanguage: Language = {
     quickTestRendererOptions: [
         { "array-type": "list" },
         { "csharp-version": "5" },
+        { "csharp-version": "8" },
         { density: "dense" },
         { "number-type": "decimal" },
         { "any-type": "dynamic" },
@@ -160,14 +161,12 @@ export const CSharpLanguageSystemTextJson: Language = {
         "minmaxlength.schema", // generated converter triggers CS8602 warnings, which "dotnet run" prints to stdout, breaking the JSON comparison
         "optional-constraints.schema", // same CS8602 stdout issue; also min/max on integers and pattern on optional strings aren't checked, so expected-failure samples don't fail
         "optional-const-ref.schema", // same CS8602 stdout issue; also min/max on integers isn't checked, so the expected-failure sample doesn't fail
-        "required.schema", // the renderer doesn't implement check-required, so the expected-failure sample doesn't fail
-        "strict-optional.schema", // the renderer doesn't implement check-required, so the expected-failure sample doesn't fail
-        "intersection.schema", // the renderer doesn't implement check-required, so the expected-failure sample doesn't fail
     ],
     rendererOptions: { "check-required": "true", framework: "SystemTextJson" },
     quickTestRendererOptions: [
         { "array-type": "list" },
         { "csharp-version": "6" },
+        { "csharp-version": "8" },
         { density: "dense" },
         { "number-type": "decimal" },
         { "any-type": "dynamic" },