ModelTransformer.mapShapes ignores location changes

[kubukoz]

When you use mapShapes to update your shapes' sourceLocation, it appears to be ignored.

Demo (scala-cli snippet):

//> using scala 3.6.3
//> using dep software.amazon.smithy:smithy-model:1.54.0
import software.amazon.smithy.model.Model
import software.amazon.smithy.model.transform.ModelTransformer
import software.amazon.smithy.model.shapes.Shape
import software.amazon.smithy.model.shapes.AbstractShapeBuilder
import software.amazon.smithy.model.shapes.StructureShape

def transform(s: Shape): Shape = {
  val sb: AbstractShapeBuilder[?, ?] = Shape
    .shapeToBuilder(s)

  sb
    .source("foo", 1, 2)
    .build()
}

val struct = StructureShape
  .builder()
  .id("foo#bar")
  .build()
// struct: StructureShape = (structure: `foo#bar`)

transform(struct).getSourceLocation()
// res0: SourceLocation = foo [1, 2]

val baseModel = Model.builder().addShape(struct).build()
// baseModel: Model = software.amazon.smithy.model.Model@5eab45b

// doesn't get updated with mapShapes
ModelTransformer
  .create()
  .mapShapes(
    baseModel,
    transform(_),
  )
  .expectShape(struct.getId())
  .getSourceLocation()
// res1: SourceLocation = N/A [0, 0]

// but it works when you create a model from scratch
Model
  .builder()
  .addShapes(
    baseModel.shapes().map(transform).toList()
  )
  .build()
  .expectShape(struct.getId())
  .getSourceLocation()
// res2: SourceLocation = foo [1, 2]

[mtdowling]

I don't have a solution, but I'm pretty sure this is caused by the fact that shape equality is not impacted by SourceLocation. So when mapShapes checks the return value, it sees the shape hasn't changed, and doesn't update it. This is the right behavior shape equality, but we might need something to account for this in the transform specifically.

[yefrig]

It is unlikely we will change the behaviour of the ModelTransformer. However, a workaround is for you to map over all the shapes that need their source location to be updated and then update them directly in your existing model as such:

existingModel.toBuilder().addShapes(<>).build();