This curious typo could be a serious bug
Here’s an interesting bug I found in my old code. It’s a small typo that completely nukes an if switch, and the best part is that it is undetected by:
- MSVC with
/W4 - clang with
-Wall -Wextra - GCC with
-Wall -Wextra
Here it is:
struct FancyString {
enum CaseSensitivity {CaseInsensitive, CaseSensitive};
bool contains(const char* what, CaseSensitivity = CaseSensitive);
};
void bug(const FancyString& log)
{
if (log.contains("exception"), FancyString::CaseInsensitive)
throw std::exception();
}
Do you see it?
The only reason I noticed is the new major release of the FancyString library added [[nodiscard]] where approapriate. That, of course, did finally catch this error, which was lurking in our codebase for many years.
Godbolt: https://godbolt.org/z/zYsb36vf9
Conclusions:
[[nodiscard]]is great, don’t be lazy and always put it where appropriate.- Compilers need more static analysis and warnings for suspicioius code constructs.