From 4ff3f205408ff8bb413d69151105d301858136ba Mon Sep 17 00:00:00 2001 From: 卜部昌平 Date: Fri, 10 Apr 2020 14:11:40 +0900 Subject: add #include guard hack According to MSVC manual (*1), cl.exe can skip including a header file when that: - contains #pragma once, or - starts with #ifndef, or - starts with #if ! defined. GCC has a similar trick (*2), but it acts more stricter (e. g. there must be _no tokens_ outside of #ifndef...#endif). Sun C lacked #pragma once for a looong time. Oracle Developer Studio 12.5 finally implemented it, but we cannot assume such recent version. This changeset modifies header files so that each of them include strictly one #ifndef...#endif. I believe this is the most portable way to trigger compiler optimizations. [Bug #16770] *1: https://docs.microsoft.com/en-us/cpp/preprocessor/once *2: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html --- missing/crypt.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'missing/crypt.h') diff --git a/missing/crypt.h b/missing/crypt.h index 7c2642f593..ff135eee93 100644 --- a/missing/crypt.h +++ b/missing/crypt.h @@ -1,3 +1,5 @@ +#ifndef CRYPT_H +#define CRYPT_H 1 /* * Copyright (c) 1989, 1993 * The Regents of the University of California. All rights reserved. @@ -30,9 +32,6 @@ * SUCH DAMAGE. */ -#ifndef CRYPT_H -#define CRYPT_H 1 - /* ===== Configuration ==================== */ #ifdef CHAR_BITS -- cgit v1.2.3