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+--- Thread: AUTOSAR C++14 M5-2-10 for unique_ptr in combination with ++ operator (/showthread.php?tid=1769)
AUTOSAR C++14 M5-2-10 for unique_ptr in combination with ++ operator - kth - 08-05-2026
The AUTOSAR C++14 Guidelines ("AUTOSAR Guidelines for the use of the C++14 language in critical and safety-related systems") contain the MISRA C++:2008 rule 5-2-10 as rule M5-2-2. M5-2-2 was modified to required but - AFAIK - nothing else was changed.
Quote:Rule M5-2-10 (required, implementation, automated)
The increment (++) and decrement ( ) operators shall not be mixed with other operators in an expression.
There is a similar MISRA C:2012/2023/2025 rule
Quote:Rule 13.3 A full expression containing an increment (++) or decrement (--) operator should have no other potential side effects other than that caused by the increment or decrement operator
Also some examples are shared:
Code:
u8a = ++u8b + u8c--; // Non-compliant
// The following sequence is clearer and therefore safer:
++u8b;
u8a = u8b + u8c;
u8c--;While this makes makes sense for C and C++, there are differences between C and C. What about the following code:
Code:
#include <cstdint>
#include <memory>
struct Data {
std::int32_t member;
};
std::int32_t main(){
std::unique_ptr<Data> d = std::make_unique<Data>(12);
d->member++; // Compliant ?
}Shall a AUTOSAR C++14/MISRA C++:2008 checker report a violation for "d->member++" or is that OK?
RE: AUTOSAR C++14 M5-2-10 for unique_ptr in combination with ++ operator - misra cpp - 08-05-2026
We think that M5-2-2 is not relevant to this topic. The relevant AUTOSAR rule is M5-2-10.
AUTOSAR took the M5-2-10 headline from that in MISRA C++::2008, and whilst that says "... should not be mixed with other operators in an expression", the rationale makes it clear that this only applies to arithmetic operators, so a checker should accept "d->member++;"