A constructor initialiser naming the base class only reaches the base constructor in C++ and JavaScript; Python, C#, Go, Rust and C treat it as a field #169

What's wrong

A MemberInitialiser named after the class's BaseType is the C++ : Base(args) idiom. C++ writes it into its initialiser list. JavaScript was fixed to honour it in #156 (for #103), in JavaScriptGenerator.WriteSuperCall. The other five generators treat it as an ordinary member named after the base:

Reproduction (at 1d544a3)

The fixture has two classes:

• Shape: field sides, constructor Shape(int sides) with initialiser sides = sides.
• Circle : Shape: field radius, constructor Circle(double radius) with initialisers Shape = 0 and radius = radius.

This is the JS DerivedClassFile fixture plus MemberInitialiser("Shape").

Results per target:

• C++: : Shape(0), radius(radius), which is correct.
• JavaScript: super(0);, which is correct.
• Python: running the generated code, Circle(1.0).sides raises AttributeError: 'Circle' object has no attribute 'sides', because Shape.__init__ never ran.
• Go: go vet reports cannot use 0 (untyped int constant) as Shape value in struct literal.
• C#: CS1061, since there is no member Shape. Without : base(0) it also hits CS7036, since Shape has no parameterless constructor.
• Rust: E0560, since there is no field Shape.
• C: compile error, since there is no struct member Shape.

Why it matters

A derived class whose base needs constructor arguments can't be expressed portably in five of the seven targets. In Python the failure is silent until a base field is read. This is the same class of bug as #103, fixed there for JS only.

Suggested fix

• Move the base-initialiser lookup out of JavaScriptGenerator.WriteSuperCall into StandardLanguageGenerator, and make it reachable from the C# generator too. The rule: an initialiser whose Name equals BaseType.Name.
• Skip that initialiser when writing members, and emit the base call in each target's form:
  • Python: super().__init__(args) as the first statement of every derived constructor, with no arguments when there's no base initialiser.
  • C#: : base(args).
  • Go: Shape: NewShape(args).
  • Rust: base: Shape::new(args).
  • C: .base = Shape_create(args).

Acceptance criteria

• The fixture above compiles or runs through the existing C, C++, Rust, Go and Python harnesses, and sides is set.
• The C# output text is pinned in a test until Generated C# is never compiled in tests and generated JavaScript is barely syntax-checked, so C# compile bugs slip through #162 adds a C# compile test.
• A Python test shows that a derived class with an explicit constructor and no base initialiser still runs the base __init__.

Related: #149 (the synthesised Python __init__ hides the base constructor when the derived class has no constructor of its own) and #103 (the JS-only version of this bug).