find-dead-code

Find 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:

1. File and line number
2. What is unused (function, type, constant, variable, import)
3. Tool that detected it (staticcheck, deadcode, goimports)
4. Classification (remove / verify / false positive)
5. Estimated lines saved

Summary: total findings, how many safe to remove, estimated cleanup size.