Recently reading some pieces of code I encountered several .cpp files that contained #pragma once in the beginning of file. I know that it is usually used in .h files as guards.

What are the cases when #pragma once should/can/must be used in .cpp files?

CodePudding user response：

#pragma once shouldn't be used in source files, its one goal is to act as include guard. I won't do much harm .cpp files are normally going to be "scanned" once during compilation anyway. Note: Clang tidy will warn you if you do it.

Warning clang-diagnostic-pragma-once-outside-header #pragma once in main file