find-dead-code

ค้นหาฟังก์ชัน ชนิด ค่าคงที่ การนำเข้า และเส้นทางโค้ดที่ไม่สามารถเข้าถึงได้ซึ่งไม่ได้ใช้งาน ใช้เมื่อผู้ใช้ขอให้ค้นหา dead code, unused code, cleanup candidates หรือ…

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:

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.