Use of the volatile qualifier

Reports any variable or field declared with the volatile qualifier.

volatile only tells the compiler not to cache a value in a register or reorder accesses to it around observable side effects; it says nothing about atomicity, memory ordering between threads, or visibility guarantees across cores. Code that reaches for volatile to make a variable safe to share between threads compiles but is not thread-safe, and the resulting data race is undefined behavior. Safety-critical and embedded coding standards restrict volatile to its one legitimate use — a genuine memory-mapped register or a signal handler variable — and forbid it everywhere else.

The following code illustrates the pattern detected by this rule:

For inter-thread communication, use std::atomic<T> (C++) or an explicit mutex/lock instead of volatile. Reserve volatile for its one legitimate use: a memory-mapped hardware register, or a sig_atomic_t variable touched by a signal handler.

This detector does not need any configuration.