Fix ApplyInterface interface source resolution

[qqxhb]

Summary

• make ApplyInterface interface source resolution more robust by using go list -json to locate the package directory and its GoFiles
• avoids relying on go/build.Default.Import (can be sensitive to unusual GOROOT/toolchain setups)
• avoids pulling in golang.org/x/tools/go/packages to reduce toolchain-compat issues in some linters

Tests

• go test ./...

[propel-code-bot]

It also adds parser fixtures and a new test to validate that GetInterfacePath correctly locates interface files.

Affected Areas

• internal/parser/export.go
• generator.go
• internal/parser/export_test.go
• internal/parser/fixtures/ifaces/ifaces.go

This summary was automatically generated by @propel-code-bot

[propel-code-bot]

LGTM, ship it! 🚢

Details

Why was this auto-approved?

✅ APPROVED: No issues detected.

[propel-code-bot]

[Documentation] The PR intent/summary says GetInterfacePath now uses golang.org/x/tools/go/packages, but the implementation here shells out to go list. If the switch to go list is intentional, please update the PR description to avoid confusion; otherwise, consider using packages.Load (e.g., with packages.NeedFiles) to align with the stated goal.

Context for Agents

The PR intent/summary says `GetInterfacePath` now uses `golang.org/x/tools/go/packages`, but the implementation here shells out to `go list`. If the switch to `go list` is intentional, please update the PR description to avoid confusion; otherwise, consider using `packages.Load` (e.g., with `packages.NeedFiles`) to align with the stated goal.

File: internal/parser/export.go
Line: 59

[propel-code-bot]

[Logic] If the runtime.Caller scan never finds a non-gen file, file stays empty and filepath.Dir(file) becomes ".", so go list runs in the current working directory. That can resolve the wrong package and make interface discovery fail silently. Guard against file == "" before running go list to surface a clear error.

Suggested change

	cmd := exec.Command("go", "list", "-json", ".")
	if file == "" {
	return nil, fmt.Errorf("go list package %s fail: failed to locate caller file", arg.PkgPath())
	}
	cmd := exec.Command("go", "list", "-json", ".")

Context for Agents

If the `runtime.Caller` scan never finds a non-gen file, `file` stays empty and `filepath.Dir(file)` becomes ".", so `go list` runs in the current working directory. That can resolve the wrong package and make interface discovery fail silently. Guard against `file == ""` before running `go list` to surface a clear error.

```suggestion
			if file == "" {
				return nil, fmt.Errorf("go list package %s fail: failed to locate caller file", arg.PkgPath())
			}
			cmd := exec.Command("go", "list", "-json", ".")
```

File: internal/parser/export.go
Line: 59

Dismissing previous approval: 1 new comment(s) require attention based on Default policy