Unused Function Parameter

ID

go.unused_method_parameter

Severity

low

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Code Smell

Language

Go

Tags

code-style, unused-code

Description

Reports function and method parameters that are never referenced in the body. The blank identifier _ is treated as an explicit "intentionally unused" marker and is never reported. Because interface satisfaction in Go is structural and cannot be proven from a single file, the rule is deliberately conservative: functions with an empty body (the classic interface-stub shape) and unnamed parameters are skipped.

Rationale

Unused parameters bloat function signatures, confuse callers about what the function actually needs, and accumulate as dead code when contracts evolve. Go already provides the blank identifier _ to mark a parameter as deliberately ignored, so a genuinely unused named parameter is almost always a mistake or leftover.

// Bad - 'unused' is never referenced
func process(used string, unused int) {  // FLAW on 'unused'
    fmt.Println(used)
}

// Good - all parameters used
func process(used string, count int) {
    for i := 0; i < count; i++ {
        fmt.Println(used)
    }
}

// Good - blank identifier marks the parameter as intentionally ignored
func handler(_ http.ResponseWriter, r *http.Request) {
    log(r.URL.Path)
}

Remediation

Remove the unused parameter from the signature, or use it in the body. If the parameter is required to satisfy an interface, rename it to the blank identifier _ to make the intent explicit.

References