Synopsis

Avoid side effects in arguments to unsafe macros.

Enabled by default

Yes

Severity/Certainty

Low/Low

Full description

An unsafe function-like macro is one whose expansion results in evaluating one of its parameters more than once or not at all. Never invoke an unsafe macro with arguments containing side effects.

Coding standards

Code examples

The following code example fails the check and will give a warning:

#define ABS(x) (((x) < 0) ? -(x) : (x))

void example(void) {
    int n = 0;
    int m = ABS(++n);
}

The following code example passes the check and will not give a warning about this issue:

#define ABS(x) (((x) < 0) ? -(x) : (x))

void example(void) {
    int n = 0;
    ++n;
    int m = ABS(n);
}