add support for formatting Nullable<GenericValueType<...>> with nullability annotations

Author: smdn

src/Smdn.Reflection.ReverseGenerating/Smdn.Reflection.ReverseGenerating/CSharpTypeFormatter.FormatTypeNameWithNullabilityAnnotation.cs

@@ -77,13 +77,16 @@ FormatTypeNameOptions options
         nullabilityAnnotationForByRefParameter = NullableAnnotationSyntaxString;
 
       // nullable value types (Nullable<>)
-      if (IsValueTupleType(nullableUnderlyingType))
+      if (IsValueTupleType(nullableUnderlyingType)) {
         // special case for nullable value tuples (Nullable<ValueTuple<>>)
         return FormatValueTuple(target, builder, options).Append(nullabilityAnnotationForByRefParameter);
-      else if (isGenericTypeClosedOrDefinition)
+      }
+      else if (nullableUnderlyingType.IsGenericType) {
         // case for nullable generic value types (Nullable<GenericValueType<>>)
-        // TODO: cannot get NullabilityInfo of generic type argument from Nullable<GenericValueType<>> (ex: KeyValuePair<int?, string?>?)
-        return builder.Append(FormatTypeNameCore(targetType, options));
+        return FormatNullableGenericValueType(target, builder, options)
+          .Append(GetNullabilityAnnotation(target))
+          .Append(nullabilityAnnotationForByRefParameter);
+      }
 
       targetType = nullableUnderlyingType;
     }
@@ -202,5 +205,28 @@ FormatTypeNameOptions options
 
     return builder.Append(')').Append(GetNullabilityAnnotation(target));
   }
+
+  private static StringBuilder FormatNullableGenericValueType(
+    NullabilityInfo target,
+    StringBuilder builder,
+    FormatTypeNameOptions options
+  )
+  {
+    if (options.TypeWithNamespace && !target.Type.IsNested)
+      builder.Append(target.Type.Namespace).Append('.');
+
+    builder
+      .Append(target.Type.GenericTypeArguments[0].GetGenericTypeName()) // the name of GenericValueType of Nullable<GenericValueType<>>
+      .Append('<');
+
+    for (var i = 0; i < target.GenericTypeArguments.Length; i++) {
+      if (0 < i)
+        builder.Append(", ");
+
+      FormatTypeNameWithNullabilityAnnotation(target.GenericTypeArguments[i], builder, options);
+    }
+
+    return builder.Append('>');
+  }
 }
 #endif // SYSTEM_REFLECTION_NULLABILITYINFO

tests/Smdn.Reflection.ReverseGenerating/Smdn.Reflection.ReverseGenerating/Generator.MemberDeclaration.Parameters.NullabilityAnnotations.cs

@@ -74,10 +74,10 @@ public void NullableNonLanguagePrimitiveRefType(Uri? p) { }
   [MemberDeclarationTestCase($"public void {nameof(ListOfKeyValuePairOfRefTypeValue)}(List<KeyValuePair<string, string>> p) {{}}", ParameterWithNamespace = false)] public void ListOfKeyValuePairOfRefTypeValue(List<KeyValuePair<string, string>> p) { }
   [MemberDeclarationTestCase($"public void {nameof(ListOfKeyValuePairOfNullableRefTypeValue)}(List<KeyValuePair<string, string?>> p) {{}}", ParameterWithNamespace = false)] public void ListOfKeyValuePairOfNullableRefTypeValue(List<KeyValuePair<string, string?>> p) { }
   [MemberDeclarationTestCase($"public void {nameof(ListOfNullableKeyValuePairOfRefTypeValue)}(List<KeyValuePair<string, string>?> p) {{}}", ParameterWithNamespace = false)] public void ListOfNullableKeyValuePairOfRefTypeValue(List<KeyValuePair<string, string>?> p) { }
-  [SkipTestCase("cannot get NullabilityInfo of generic type argument from Nullable<GenericValueType<>>")] [MemberDeclarationTestCase($"public void {nameof(ListOfNullableKeyValuePairOfNullableRefTypeValue)}(List<KeyValuePair<string, string?>?> p) {{}}", ParameterWithNamespace = false)] public void ListOfNullableKeyValuePairOfNullableRefTypeValue(List<KeyValuePair<string, string?>?> p) { }
+  [MemberDeclarationTestCase($"public void {nameof(ListOfNullableKeyValuePairOfNullableRefTypeValue)}(List<KeyValuePair<string, string?>?> p) {{}}", ParameterWithNamespace = false)] public void ListOfNullableKeyValuePairOfNullableRefTypeValue(List<KeyValuePair<string, string?>?> p) { }
   [MemberDeclarationTestCase($"public void {nameof(NullableListOfKeyValuePairOfRefTypeValue)}(List<KeyValuePair<string, string>>? p) {{}}", ParameterWithNamespace = false)] public void NullableListOfKeyValuePairOfRefTypeValue(List<KeyValuePair<string, string>>? p) { }
   [MemberDeclarationTestCase($"public void {nameof(NullableListOfKeyValuePairOfNullableRefTypeValue)}(List<KeyValuePair<string, string?>>? p) {{}}", ParameterWithNamespace = false)] public void NullableListOfKeyValuePairOfNullableRefTypeValue(List<KeyValuePair<string, string?>>? p) { }
-  [SkipTestCase("cannot get NullabilityInfo of generic type argument from Nullable<GenericValueType<>>")] [MemberDeclarationTestCase($"public void {nameof(NullableListOfNullableKeyValuePairOfNullableRefTypeValue)}(List<KeyValuePair<string, string?>?>? p) {{}}", ParameterWithNamespace = false)] public void NullableListOfNullableKeyValuePairOfNullableRefTypeValue(List<KeyValuePair<string, string?>?>? p) { }
+  [MemberDeclarationTestCase($"public void {nameof(NullableListOfNullableKeyValuePairOfNullableRefTypeValue)}(List<KeyValuePair<string, string?>?>? p) {{}}", ParameterWithNamespace = false)] public void NullableListOfNullableKeyValuePairOfNullableRefTypeValue(List<KeyValuePair<string, string?>?>? p) { }
 
   class Params {
     [MemberDeclarationTestCase($"public void {nameof(ArrayOfValueType)}(params int[] p) {{}}")] public void ArrayOfValueType(params int[] p) { }

tests/Smdn.Reflection.ReverseGenerating/Smdn.Reflection.ReverseGenerating/Generator.MemberDeclaration.ReturnParameters.NullabilityAnnotations.cs

@@ -59,10 +59,10 @@ public class NullabilityAnnotations {
   [MemberDeclarationTestCase($"public List<KeyValuePair<string, string>> {nameof(ListOfKeyValuePairOfRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string>> ListOfKeyValuePairOfRefTypeValue() => throw null;
   [MemberDeclarationTestCase($"public List<KeyValuePair<string, string?>> {nameof(ListOfKeyValuePairOfNullableRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string?>> ListOfKeyValuePairOfNullableRefTypeValue() => throw null;
   [MemberDeclarationTestCase($"public List<KeyValuePair<string, string>?> {nameof(ListOfNullableKeyValuePairOfRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string>?> ListOfNullableKeyValuePairOfRefTypeValue() => throw null;
-  [SkipTestCase("cannot get NullabilityInfo of generic type argument from Nullable<GenericValueType<>>")] [MemberDeclarationTestCase($"public List<KeyValuePair<string, string?>?> {nameof(ListOfNullableKeyValuePairOfNullableRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string?>?> ListOfNullableKeyValuePairOfNullableRefTypeValue() => throw null;
+  [MemberDeclarationTestCase($"public List<KeyValuePair<string, string?>?> {nameof(ListOfNullableKeyValuePairOfNullableRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string?>?> ListOfNullableKeyValuePairOfNullableRefTypeValue() => throw null;
   [MemberDeclarationTestCase($"public List<KeyValuePair<string, string>>? {nameof(NullableListOfKeyValuePairOfRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string>>? NullableListOfKeyValuePairOfRefTypeValue() => throw null;
   [MemberDeclarationTestCase($"public List<KeyValuePair<string, string?>>? {nameof(NullableListOfKeyValuePairOfNullableRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string?>>? NullableListOfKeyValuePairOfNullableRefTypeValue() => throw null;
-  [SkipTestCase("cannot get NullabilityInfo of generic type argument from Nullable<GenericValueType<>>")] [MemberDeclarationTestCase($"public List<KeyValuePair<string, string?>?>? {nameof(NullableListOfNullableKeyValuePairOfNullableRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string?>?>? NullableListOfNullableKeyValuePairOfNullableRefTypeValue() => throw null;
+  [MemberDeclarationTestCase($"public List<KeyValuePair<string, string?>?>? {nameof(NullableListOfNullableKeyValuePairOfNullableRefTypeValue)}() {{}}", MemberWithNamespace = false)] public List<KeyValuePair<string, string?>?>? NullableListOfNullableKeyValuePairOfNullableRefTypeValue() => throw null;
 
   class Modifiers {
     class Ref {