Searching for Does Gcc Support Pragma Once information? Find all needed info by using official links provided below.
https://stackoverflow.com/questions/28772519/does-mingw-4-8-2-support-pragma-once
The real question is whether gcc (the compiler portion of the MinGW system) supports #pragma once. The answer is yes. The #pragma feature is actually supported by the C preprocessor used by gcc, which is documented separately. Gnu CPP's implementation of #pragma once is described here.
https://www.howtobuildsoftware.com/index.php/how-do/PE2/gcc-mingw-does-mingw-482-support-pragma-once
The real question is whether gcc (the compiler portion of the MinGW system) supports #pragma once. The answer is yes. The #pragma feature is actually supported by the C preprocessor used by gcc, which is documented separately. Gnu CPP's implementation of #pragma once is described here. Depending on how your system is configured, you might be able to read this on your system by typing …
https://dmalcolm.fedorapeople.org/gcc/2015-08-31/rst-experiment/pragmas-accepted-by-gcc.html
Pragmas Accepted by GCC¶ GCC supports several types of pragmas, primarily in order to compile code originally written for other compilers. Note that in general we do not recommend the use of pragmas; See Declaring Attributes of Functions, for further explanation.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58770
The GCC preprocessor is very optimized for include guards. Perhaps the same optimizations are not applied for "#pragma once". Someone will need to investigate where the two code paths differ and what could be the reason for the slow-down.
https://stackoverflow.com/questions/1143936/pragma-once-vs-include-guards
If you're positive that you will never use this code in a compiler that doesn't support it (Windows/VS, GCC, and Clang are examples of compilers that do support it), then you can certainly use #pragma once without worries.
https://en.wikipedia.org/wiki/Pragma_once
In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as include guards, but with several advantages, including: less code, avoidance of name clashes, and sometimes improvement in …
https://www.geeksforgeeks.org/pragma-directive-in-c-c/
This happens because GCC does not support #pragma startup or exit. However, you can use the below code for a similar output on GCC compilers. However, you …
https://en.cppreference.com/w/cpp/preprocessor/impl
#pragma once is a non-standard pragma that is supported by the vast majority of modern compilers. If it appears in a header file, it indicates that it is only to be parsed once, even if it is (directly or indirectly) included multiple times in the same source file.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=11569
#pragma once used in a .h file indicates that it is only to be parsed once, even if it is (directly or indirectly) included multiple times in the same source file. However, every time you use this pragma, you get a warning saying it is "obsolete", and there seems to be no compiler option to turnoff this warning.
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