---
id: "bug-1440"
status: "fixed"
status_updated: "2026-09-24"
status_note: "b7b90e9d"
component: "apiserver"
severity: "unknown"
timestamp: "2026-07-15T09:35:00Z"
last_seen: "2026-09-19T09:00:00Z"
occurrences: 1
files: ["src/frontend/apiserver/backend/wire_dispatch_test.go"]
tags: ["cgo", "go-test", "toolchain-limitation", "wire_dispatch_test", "job-array-single-wal-record", "backend-package", "build-error", "golang-go-13938"]
related: []
fix_commits: ["b7b90e9d"]
legacy: true
---

# bug-1440: use of cgo in test wire_dispatch_test.go not supported / FAIL apiserver/backend [setup failed]

## Description
use of cgo in test wire_dispatch_test.go not supported / FAIL apiserver/backend [setup failed]

## Environment
_Not recorded (migrated from buglog.json)._

## Reproduction
_Not recorded (migrated from buglog.json)._

## Root cause
Go toolchain hard restriction, not an environment/CGO_CFLAGS/nix issue: cmd/go's module indexer (GOROOT share/go/src/cmd/go/internal/modindex/read.go, ~line 589, inside the per-file import scan) explicitly checks `if imp.path == "C" { if isTest { badGoFile(name, fmt.Errorf("use of cgo in test %s not supported", name)) } }`. Any `_test.go` file that directly does `import "C"` is rejected outright the moment CGO is active for that file (CGO_ENABLED=1 and the file's build tag, here `//go:build cgo`, is satisfied) -- this is golang/go#13938, a long-standing toolchain limitation, confirmed by reading the actual installed Go 1.25.5 source in the nix shell. Because wire_dispatch_test.go and clib.go/convert.go/peers_test.go/handler_test.go/convert_test.go/heartbeat_test.go (the last four carry no build tag, so they build under BOTH cgo and !cgo) all live in the same package, the ENTIRE apiserver/backend package fails as `[setup failed]` under `make test-backend` (CGO_ENABLED=1) -- this also silently prevented the pre-existing cgo-buildable tests (handler_test.go, convert_test.go, peers_test.go, heartbeat_test.go) from running, even though none of them regressed on their own. The `!cgo`-tagged files (integration_test.go, control_host_test.go, stub_funcs_test.go) are unaffected since they're excluded from the CGO_ENABLED=1 file set entirely; `make test` (CGO_ENABLED=0) passed clean (apiserver/backend ok, 1.510s) confirming no regression on the non-cgo path.

## Fix
NOT FIXED -- user explicitly instructed build/run/report only, no source edits. Reported fix path for the user: remove `import "C"` (and any direct `C.xxx` calls) from wire_dispatch_test.go itself; move the cgo-dependent helpers (buildEncodedJobArrayPush, deliverViaRealDispatchChain, and the `/* ... */ import "C"` preamble with the wire_test_* static C helpers) into a new non-test `.go` file in the same package (e.g. clib_wire_test_helpers.go, `//go:build cgo`), exposing plain-Go-signature functions the _test.go file can call without itself using cgo directly. This mirrors the established pattern already used for other CGO test-only helpers in this package. Because the file was rejected before type-checking, it is unknown whether wire_dispatch_test.go has any further errors (undefined C symbols, type mismatches) beyond this first, blocking one -- those can only be discovered after this structural fix.

## Verification
_Not recorded (migrated from buglog.json)._

## References
_Not recorded (migrated from buglog.json)._