Attempt to use AST-based code rewriting to rewrite code for using Uber FX. Starting out with a particular use case.

This expects a module that has:

1. Some struct such as

type X struct {
 Field1 Type1
 Field2 Type2
 ...
}

2. And a constructor NewX such as:

func NewX(Field1 Type1, Field2 Type2, ...) X

or

func NewX(Field1 Type1, Field2 Type2, ...) *X

(The return type can either be a value X or pointer to it *X).

The behavior is to walk through the code and rewrite it as follows:

1. Add an XParams struct:

type X struct {
 fx.In
 
 Field1 Type1
 Field2 Type2
 ...
}

(For why the duplication of the fields is needed instead of just embedding X in XParams, see discussion at uber-go/fx#1110.

2. Replace NewX constructor with NewXOrig.

3. Add a new constructor NewX such as:

func NewX(params XParams) X {
  diutils.ConstructVal[X, XParams](params)
}

or

func NewX(params XParams) *X {
  diutils.Construct[X, XParams](params)
}

The diutils.Construct() or diutils.ConstructVal() uses reflection to properly assign fields.

4. Add, if needed, appropriate imports: go.uber.org/fx and/or github.com/debedb/fxforce5/diutils.

5. Add, if needed, the above dependencies into go.mod (TODO).

6. Add an fx.Module var:

var X = fx.Module("X", fx.Provide(NewX))

• uber-go/fx#1110