public static IType MapType()

in ReSharper.FSharp/src/FSharp/FSharp.Psi/src/Util/FcsTypeMappingUtil.cs [108:180]
62 lines of code
22 McCabe index (conditional complexity)

    public static IType MapType([NotNull] this FSharpType fcsType, [NotNull] IList<ITypeParameter> typeParams,
      [NotNull] IPsiModule psiModule, bool isFromMethod = false, bool isFromReturn = false)
    {
      var type = GetStrippedType(fcsType);
      if (type == null || type.IsUnresolved)
        return TypeFactory.CreateUnknownType(psiModule);

      // F# 4.0 specs 18.1.3
      try
      {
        // todo: check type vs fcsType
        if (isFromMethod && type.IsNativePointerType && !HasGenericTypeParams(fcsType))
        {
          var argType = GetSingleTypeArgument(fcsType, typeParams, psiModule, true);
          return TypeFactory.CreatePointerType(argType);
        }
      }
      catch (Exception e)
      {
        Logger.LogMessage(LoggingLevel.WARN, "Could not map pointer type: {0}", fcsType);
        Logger.LogExceptionSilently(e);
      }

      if (isFromReturn && type.IsUnitType)
        return psiModule.GetPredefinedType().Void;

      if (type.IsGenericParameter)
        return GetTypeParameterByName(type, typeParams, psiModule);

      if (!type.HasTypeDefinition)
        return TypeFactory.CreateUnknownType(psiModule);

      var entity = type.TypeDefinition;
      // F# 4.0 specs 5.1.4
      if (entity.IsArrayType)
      {
        var argType = GetSingleTypeArgument(type, typeParams, psiModule, isFromMethod);
        return TypeFactory.CreateArrayType(argType, type.TypeDefinition.ArrayRank, NullableAnnotation.Unknown);
      }

      // e.g. byref<int>, we need int
      if (entity.IsByRef)
        return MapType(type.GenericArguments[0], typeParams, psiModule, isFromMethod, isFromReturn);

      if (entity.IsProvidedAndErased)
        return entity.BaseType is { } baseType
          ? MapType(baseType.Value, typeParams, psiModule, isFromMethod, isFromReturn)
          : TypeFactory.CreateUnknownType(psiModule);

      // todo: prevent getting clr name
      var clrName = entity.GetClrName();
      if (clrName == null)
      {
        // bug Microsoft/visualfsharp#3532
        // e.g. byref<int>, we need int
        return entity.CompiledName == "byref`1" && entity.AccessPath == "Microsoft.FSharp.Core"
          ? MapType(type.GenericArguments[0], typeParams, psiModule, isFromMethod, isFromReturn)
          : TypeFactory.CreateUnknownType(psiModule);
      }

      if (entity.IsProvidedAndGenerated &&
          ProvidedTypesResolveUtil.TryGetProvidedType(psiModule, clrName, out var providedType))
        return MapType(providedType, psiModule);

      var typeElement = entity.GetTypeElement(psiModule);
      if (typeElement == null)
        return TypeFactory.CreateUnknownType(psiModule);

      var genericArgs = type.GenericArguments;
      return genericArgs.IsEmpty()
        ? TypeFactory.CreateType(typeElement)
        : GetTypeWithSubstitution(typeElement, genericArgs, typeParams, psiModule, isFromMethod);
    }