No Unmodified Loop

ID

go.no_unmodified_loop

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Go

Tags

reliability, suspicious

Description

Reports a condition-only for cond { …​ } loop whose condition variables are never modified anywhere in the body and that has no other way to exit.

Rationale

The loop never makes progress towards its termination test: if the condition is true on entry it spins forever, and if false it never runs once. This is almost always a forgotten increment, a missing reassignment, or a guard placed on the wrong variable. A loop that modifies a condition variable, contains a break/return/goto, or passes a condition variable to a callee (which could mutate it through a pointer) is not reported.

// Bad
for i < n { fmt.Println(i) }   // FLAW — neither i nor n changes; never terminates

// Good
for i < n { i++ }              // OK — i is modified
for !done { done = next() }    // OK — done is reassigned

Remediation

Update a condition variable inside the loop body, or add an explicit exit (break/return) so the loop can terminate.

References