find-dead-code
Find unused functions, types, constants, imports, and unreachable code paths. Use when the user asks to find dead code, unused code, cleanup candidates, or…
npx skills add https://github.com/openshift/lightspeed-operator --skill find-dead-codeFind Dead Code
Detect unused Go code that can be safely removed.
Rules
- Report findings, do not delete. Removal is a separate task.
- Focus on production code (
internal/,api/,cmd/). Skip tests unless explicitly asked. - Tools have false positives — classify each finding before recommending removal.
- Code used via reflection or dynamic dispatch (e.g. Kubernetes controller-runtime, interface implementations) is not dead.
Step 1: Determine Scope
Ask the user:
- Branch mode: only files changed in the current branch vs main.
- Full mode: scan the entire codebase.
For branch mode:
git diff --name-only upstream/main -- 'internal/' 'api/' 'cmd/' | grep '\.go$' | grep -v '_test\.go$'
Step 2: Run Go Standard Tooling
Check for unused code with the compiler:
go build ./... 2>&1 | grep "declared and not used"
go vet ./... 2>&1 | grep -E "(not used|never used)"
Step 3: Run staticcheck
staticcheck detects unused code, including unexported functions, constants, and variables:
staticcheck -checks=U1000 ./...
U1000 reports unused code that is not exported and not referenced.
Step 4: Run deadcode (Go 1.23+)
If Go 1.23+ is available:
go run golang.org/x/tools/cmd/deadcode@latest -filter <package-pattern>
This finds functions, types, and variables that are never called or referenced.
Step 5: Check Unused Imports
goimports -l <target>
Any file listed has unused imports. Review with:
goimports -d <file>
Step 6: Filter False Positives
Common false positives in this codebase:
| Pattern | Why it's not dead |
|---|---|
Reconcile(ctx, req) implementations | Called by controller-runtime via interface |
SetupWithManager() functions | Called by manager setup code |
init() functions | Called automatically by Go runtime |
| Interface method implementations | Called through interface, not directly |
kubebuilder: marker functions | Used by code generation |
Constants/vars in constants.go | May be used in tests or future code |
Error constants matching Err* pattern | May be used in error wrapping |
Step 7: Classify Findings
For each finding, classify:
| Category | Criteria | Action |
|---|---|---|
| Remove | Clearly unused, no interface/reflection use | Safe to delete |
| Verify | Possibly used dynamically or via interface | Search for references before removing |
| False positive | Interface impl, reflection, kubebuilder marker | Skip |
For "Verify" findings, search for references:
rg "<function_or_type_name>" internal/ api/ cmd/ test/
Step 8: Report
For each finding:
- File and line number
- What is unused (function, type, constant, variable, import)
- Tool that detected it (staticcheck, deadcode, goimports)
- Classification (remove / verify / false positive)
- Estimated lines saved
Summary: total findings, how many safe to remove, estimated cleanup size.