The possibilities of ISO C printf format strings are limited, this is why many extensions have been added by several implementations.
Even though they are widespread and similar in many implementations, they are not standard, which means that using them may create portability
issues.
This rule reports an issue when format strings do not comply with ISO C standards.
Noncompliant code example
void test() {
printf("%1$d", 1); // Noncompliant; positional arguments are not supported by ISO C
printf("%qd", (long long)1); // Noncompliant; length specifier "q" is not supported by ISO C
}
