Given a mixin like this:

type FooMixin struct {
	mixin.Schema
}

func (FooMixin) Fields() []ent.Field {
	return []ent.Field{
		field.String("fooUrl").
			StorageKey("foo_url").
			SchemaType(/* ... */).
			GoType(new(url.URL)).
			ValueScanner(field.BinaryValueScanner[*url.URL]{}),
	}
}

The generated code does not compile. Digging in, the issue is that it doesn't generate a variable declaration due to this logic:

My guess at a solution:

• The ent/entc/gen.Field type needs a flag for whether it has a value scanner ~

  ent/entc/gen/type.go

  Line 94 in 5368e5c

  Validators int

• This needs to be copied over ~

  ent/entc/gen/type.go

  Line 252 in 5368e5c

  Validators: f.Validators,

• The template needs to add this to the list of things that cause a field to be reported in MixedInFields ~

  ent/entc/gen/type.go

  Line 469 in 5368e5c

  if f.Position != nil && f.Position.MixedIn && (f.Default || f.UpdateDefault || f.Validators > 0) {

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

NOTE: This sounds similar to #3255, but on closer inspection they seem like independent issues AFAICT.

Current Behavior 😯

Generated code fails to compile due to attempting to reference an undeclared local variable.

Expected Behavior 🤔

Generated code should declare the variable so it compiles.

Steps to Reproduce 🕹

Repro repo: https://github.com/mgabeler-lee-6rs/entbug-3785
Build output:

entbug-3785$ go build -v ./...
entgo.io/bug/ent
# entgo.io/bug/ent
ent/runtime.go:6:2: "net/url" imported and not used
ent/runtime.go:10:2: "entgo.io/ent/schema/field" imported and not used
ent/runtime.go:20:17: undefined: userMixinFields0

(I think the unused import problem will go away with the fix, not sure, but I personally normally run a formatter over generated code anyways that cleans up such things for me)

Steps:

1. Add a mixin like the above to a schema type
2. Generate the code
3. Try to compile it

Workaround

Add a no-op custom validator to the mixed in field so that the template declares the variable.

Your Environment 🌎