The check finds usages of sizeof on expressions of STL container types. Most likely the user wanted to use .size() instead.

All class/struct types declared in namespace std:: having a const size() method are considered containers, with the exception of std::bitset and std::array.


std::string s;
int a = 47 + sizeof(s); // warning: sizeof() doesn't return the size of the container. Did you mean .size()?

int b = sizeof(std::string); // no warning, probably intended.

std::string array_of_strings[10];
int c = sizeof(array_of_strings) / sizeof(array_of_strings[0]); // no warning, definitely intended.

std::array<int, 3> std_array;
int d = sizeof(std_array); // no warning, probably intended.