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+---- Thread: Rule 7.0.2: Unclear/questionable rationale (/showthread.php?tid=1718)
Rule 7.0.2: Unclear/questionable rationale - cgpzs - 06-12-2024
Hi,
Rule 7.0.2 bans any type of conversion to bool (implicit or explicit) anywhere in the code (with some exceptions). The rationale says:
"However, this interpretation may not be appropriate for APIs, such as POSIX, that do not use Boolean return values."
This sounds strange, why should modern C++17 code (that may not use C-style POSIX functions at all) be limited by this?
Could you show an example code that highlights how this is a problem and leads to unexpected behavior? For example, how is this code unsafe/can lead to unexpected results?
Code:
bool b1 = static_cast< bool >( 4 ); // Non-compliantConversion from fundamental types to bool is well-defined behavior as per [conv.bool]:
"A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true."
Thanks!
RE: Rule 7.0.2: Unclear/questionable rationale - misra cpp - 20-12-2024
The issue is with functions like strcmp, where an implicit conversion to bool may not give the answer expected (0 being equality)
Also in a case like if (a = b) .... (though this is also non-compliant with another rule)