06-01-2025, 11:56 AM
Hi,
as I understand it right now, rule 7.0.5 is very strict and often prevents unsigned integer types smaller than int from being used in a MISRA-compliant way. For example, take
Here, integral promotions happen on both the lhs and rhs of the == operator. Both are implicitly converted to int, thus changing from unsigned to signed, causing a violation to MisraC++ 2023 Rule 7.0.5.
But does Rule 7.0.5 even apply in this case? The rule is supposed to apply to "all expressions (including sub-expressions) of _numeric_ type". "cu8a == cu16a" is of type bool, so the rule does not apply to the full expression. However, the expressions on the LHS and RHS individually are of a numerical type and consist of the implicit "(int)cu8a" / "(int)cu16a.
The rule also states "For the usual arithmetic conversions, only the final type of an operand is considered." Which could suggest a restriction for operators that return integral types (otherwise the expression itself would not be of integral type and not considered at all).
The same case could be made with an implicit cast to bool, eg taking the sum or difference of cu8a and cu16a.
How exactly is the rule supposed to be scoped and what expressions / operands does it consider?
as I understand it right now, rule 7.0.5 is very strict and often prevents unsigned integer types smaller than int from being used in a MISRA-compliant way. For example, take
Code:
const uint8_t cu8a = 0;
const uint16_t cu16a = 0;
static_assert(cu8a == cu16a);Here, integral promotions happen on both the lhs and rhs of the == operator. Both are implicitly converted to int, thus changing from unsigned to signed, causing a violation to MisraC++ 2023 Rule 7.0.5.
But does Rule 7.0.5 even apply in this case? The rule is supposed to apply to "all expressions (including sub-expressions) of _numeric_ type". "cu8a == cu16a" is of type bool, so the rule does not apply to the full expression. However, the expressions on the LHS and RHS individually are of a numerical type and consist of the implicit "(int)cu8a" / "(int)cu16a.
The rule also states "For the usual arithmetic conversions, only the final type of an operand is considered." Which could suggest a restriction for operators that return integral types (otherwise the expression itself would not be of integral type and not considered at all).
The same case could be made with an implicit cast to bool, eg taking the sum or difference of cu8a and cu16a.
How exactly is the rule supposed to be scoped and what expressions / operands does it consider?