fn add_variant_discriminant(
sema: &Semantics<'_, RootDatabase>,
builder: &mut SourceChangeBuilder,
variant_node: &Variant,
radix: &mut Radix,
)fn add_variant_discriminant(
sema: &Semantics<'_, RootDatabase>,
builder: &mut SourceChangeBuilder,
variant_node: &Variant,
radix: &mut Radix,
)