CLI Version

0.45.0-rc44 - the absolute most bleeding-edge version of the CLI

Generator Version

0.23.5 - observed in fern-go-fiber and fern-go-model

Describe the Bug

When defining an API spec with a timestamp type on an undiscriminated union, I observed the latest version of the generator for fern-go-fiber (and fern-go-model in testing) acting up on the Go source code it generated:

> fern generate
# (snip deprecations)
[api]: ✓ All checks passed
┌─
[api]: fernapi/fern-go-fiber failed to parse Go code: logs\types.go:676:55: expected ';', found '{' (and 3 more errors)  
[api]: fernapi/fern-openapi Downloaded to <>\models\openapi
┌─
│ ✓  fernapi/fern-openapi
│ x  fernapi/fern-go-fiber
└─

Additional Context

After doing some magic to get local development working again, I did a deep dive:

• Instrumented additional logging into generator/go with some fmt.Errorf wraps to drill down to the generated source (where this error is emitted, in generators/go/internal/generator/file_writer.go)
• Added some printing of the troublesome generated source
• Observed the following, since up to this point I had no idea what was going on:

> ..\..\fern\generators\go\build\fern-go-fiber.exe config.json
failed to run: failed to parse Go code: logs\types.go:676:55: expected ';', found '{' (and 3 more errors); source:
=-=
672: }
674: return json.Marshal(l.String)
675: }

676: if l.typ == "Timestamp" || l.Timestamp != time.Time{} {
                                                        ^
677: return json.Marshal(l.Timestamp)
678: }
679: return nil, fmt.Errorf("type %T does not include a non-empty union type", l)
680: }

• Aha, that's a golang parser no-no!
• Found the generator source that controls this:
  
• Looks like it's in VisitUndiscriminatedUnion...
• To be safe, I wrap each full if statement in parentheses to resolve -> and a subsequent local build + execution shows successful generation.

I made the needed changes to fix this on a fork, will make a PR shortly stemming from this issue! I will leave the improved error / generated source logging changes as a separate commit to let them be cherry-picked out.