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+---- Thread: How do explicit casts of arguments affect 21.15 (amendment 1)? (/showthread.php?tid=1415)
How do explicit casts of arguments affect 21.15 (amendment 1)? - abgs - 09-04-2018
When rule 21.15 of MISRA C 2012 Amendment 1 refers to the types that pointer arguments are pointers to, how are explicit casts interpreted? Are the types that they are pointers to considered before or after the cast?
Code:
void f(signed char* a, int* b, size_t n) {
memcmp(a, a, n); // ok - pointers to same type
memcmp(b, b, n); // ok - pointers to same type
memcmp((int*)b, (int*)b, n); // ok - same type and cast has no effect
memcmp((int*)a, (int*)a, n); // ok? - cast to different pointer type, arguments match before and after but with different matching types
memcmp(a, b, n); // violation - pointers to different types
memcmp((int*)a, b, n); // violation? - types only match due to pointer cast
memcmp((float*)a, (float*)b, n); // violation? - different pointer types cast to third common pointer type
memcmp((short*)a, a, n); // violation? - original pointer types match before cast
}Re: How do explicit casts of arguments affect 21.15 (amendment 1)? - misra-c - 24-04-2018
Rule 21.15 applies to the types after casting.
Code:
void f(signed char* a, int* b, size_t n) {
memcmp(a, a, n); // Compliant
memcmp(b, b, n); // Compliant
memcmp((int*)b, (int*)b, n); // Compliant
memcmp((int*)a, (int*)a, n); // Compliant - but violates Rule 11.3
memcmp(a, b, n); // Non-Compliant
memcmp((int*)a, b, n); // Compliant - but violates Rule 11.3
memcmp((float*)a, (float*)b, n); // Compliant - but violates Rules 11.3 and 21.16
memcmp((short*)a, a, n); // Non-Compliant - and also violates Rule 11.3
}