Single Case Select

ID

go.single_case_select

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Code Smell

Language

Go

Tags

code-style, concurrency

Description

Reports a select statement that has exactly one communication case and no default clause. A single-case select blocks on one channel operation, which is identical to performing that operation directly.

Rationale

select exists to wait on several channel operations at once, or — with a default — to attempt one without blocking. A select with a single case and no default does neither: it simply blocks on that one operation, so v := ←ch says the same thing with less ceremony. The wrapper is usually a leftover from a version that once had multiple cases, and it hides the intent.

// FLAW — equivalent to `v := <-ch`
select {
case v := <-ch:
    use(v)
}

// OK — the default makes this a non-blocking receive
select {
case v := <-ch:
    use(v)
default:
    // nothing ready
}

Remediation

Replace the single-case select with the channel operation it wraps (v := ←ch). Keep the select only when there is more than one case, or when a default clause provides non-blocking behaviour.

References