[THRIFT-4290] C# nullable option generates invalid code for non-required enum field with default value

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.9.3, 0.10.0
• Fix Version/s: 0.11.0
• Component/s: C# - Compiler

Environment

Windows

• Assignee: James E. King III
• Reporter: Dirk Sandbrink
• Created: 21/Aug/17 19:24
• Updated: 14/Dec/17 13:55
• Resolved: 07/Sep/17 17:32

Description

When generating C# code with the nullable option invalid setter code is generated for enum fields which have a default value (and thus still need an isset flag).

For example use the Work struct from tutorial.thrift and add a default value to the enum field:

struct Work {
  1: i32 num1 = 0,
  2: i32 num2,
  3: Operation op = Operation.ADD,
  4: optional string comment,
}

Then the generated code in Work.cs looks like this:

  public Operation? Op
  {
    get
    {
      return _op;
    }
    set
    {
      __isset.op = true;
      this._op = value;
    }
  }

This code is invalid, because value is of type Operation?, the correct code should be:

  public Operation? Op
  {
    get
    {
      return _op;
    }
    set
    {
      __isset.op = value.HasValue;
      if (value.HasValue) this._op = value.Value;
    }
  }

I believe the error is located in file t_csharp_generator.cc in function t_csharp_generator::generate_csharp_property:

      if (ttype->is_base_type()) {
        use_nullable = ((t_base_type*)ttype)->get_base() != t_base_type::TYPE_STRING;
      }

Here use_nullable is set to true for all base types other then string, but not for enums.
A quick fix might be to add

      else if (ttype->is_enum()) {
        use_nullable = true;
      }

Issue Links

• links to: GitHub Pull Request #1347