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 #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 info cpp and search for #pragma once.
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 …
https://dmalcolm.fedorapeople.org/gcc/2015-08-31/rst-experiment/pragmas-accepted-by-gcc.html
Structure-Packing Pragmas¶. For compatibility with Microsoft Windows compilers, GCC supports a set of #pragma directives that change the maximum alignment of members of structures (other than zero-width bit-fields), unions, and classes subsequently defined. The n value below always is required to be a small power of two and specifies the new alignment in bytes.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58770
Created attachment 31026 Benchmark files Putting #pragma once in a header file, with or without additional classic include guards, makes GCC very slow. I've created a small benchmark that I'm attaching, with the following files: * common.h: a common file to be included 10,000 times, protected with guards or the pragma.
https://www.reddit.com/r/cpp/comments/ajltg/whats_wrong_with_pragma_once/
Even if gcc and msvc support it - other compilers might not. Many compilers recognize include guards as special cases. (usually the same ones that support #pragma once). But at least include guards work on all compilers. Usually if you're targeting a device that uses a compiler that doesn't support #pragma once, the compilation time benefit you ...
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://stackoverflow.com/questions/1143936/pragma-once-vs-include-guards
I generally don't bother with #pragma once as my code sometimes does have to compile with something other than MSVC or GCC (compilers for embedded systems don't always have the #pragma). So I have to use #include guards anyway.
https://www.geeksforgeeks.org/pragma-directive-in-c-c/
Sep 11, 2018 · #pragma GCC dependency "parse.y" #pragma GCC dependency "/usr/include/time.h" rerun fixincludes #pragma GCC system_header: This pragma takes no arguments. It causes the rest of the code in the current file to be treated as if it came from a system header. #pragma once: The #pragma once directive has a very simple concept. The header file ...1.8/5
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.
https://www.reddit.com/r/cpp/comments/8devw1/can_anyone_actually_name_a_compiler_that_doesnt/
I use GCC, MSVC, Clang on linux, macOS and windows, cross-compiling or not, with distcc, ccache or icecc, use #pragma once in all my code, and never once had a problem due to it. However I spent hours debugging people who had copy-pasted include directives from one file to another.
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