The analyzer has detected an attempt to iterate an empty container. As a result, not a single iteration of the loop will occur. This may indicate an error.
Let's look at the example that may be the result of unsuccessful refactoring:
#include <vector> #include <string_view> std::vector<std::string_view> GetSystemPaths() { std::vector<std::string_view> paths; #ifdef _WIN32 paths.emplace_back("C:/Program files (x86)/Windows Kits"); paths.emplace_back("C:/Program Files (x86)/Microsoft Visual Studio"); #elif defined(__APPLE__) paths.emplace_back("/Applications"); paths.emplace_back("/Library"); paths.emplace_back("/usr/local/Cellar"); #elif defined(__linux__) // TODO: Don't forget to add some specific paths #endif return paths; } bool IsSystemPath(std::string_view path) { static const auto system_paths = GetSystemPaths(); for (std::string_view system_path : system_paths) { if (system_path == path) { return true; } } return false; }
The content of the 'system_paths' container depends on the operating system for which the application is compiled. For Linux and all other systems except Windows and macOS, an empty container is obtained as a result of the preprocessor directives expansion.
In the context of this example, this is an undesirable behavior of the 'GetSystemPaths' function. In the case of Linux, to fix the warning, a developer needs to add the necessary paths. When compiling to a new operating system (for example, FreeBSD) a developer may need to handle an error with static_assert. Here is the example of safe code:
#include <vector> #include <string_view> std::vector<std::string_view> GetSystemPaths() { std::vector<std::string_view> paths; #ifdef _WIN32 .... #elif defined(__APPLE__) .... #elif defined(__linux__) paths.emplace_back("/usr/include/"); paths.emplace_back("/usr/local/include"); #else static_assert(false, "Unsupported OS."); #endif return paths; }
In general, if an empty container iteration was the programmer's intent, then the warning can be suppressed.