diff options
Diffstat (limited to 'include/ansidecl.h')
| -rw-r--r-- | include/ansidecl.h | 40 |
1 files changed, 33 insertions, 7 deletions
diff --git a/include/ansidecl.h b/include/ansidecl.h index 6e4bfc21f2..25f33dad23 100644 --- a/include/ansidecl.h +++ b/include/ansidecl.h @@ -1,5 +1,5 @@ /* ANSI and traditional C compatability macros - Copyright (C) 1991-2015 Free Software Foundation, Inc. + Copyright (C) 1991-2017 Free Software Foundation, Inc. This file is part of the GNU C Library. This program is free software; you can redistribute it and/or modify @@ -252,7 +252,7 @@ So instead we use the macro below and test it against specific values. */ # endif /* GNUC >= 3.0 */ #endif /* ATTRIBUTE_ALIGNED_ALIGNOF */ -/* Useful for structures whose layout must much some binary specification +/* Useful for structures whose layout must match some binary specification regardless of the alignment and padding qualities of the compiler. */ #ifndef ATTRIBUTE_PACKED # define ATTRIBUTE_PACKED __attribute__ ((packed)) @@ -313,13 +313,39 @@ So instead we use the macro below and test it against specific values. */ #define ENUM_BITFIELD(TYPE) unsigned int #endif - /* This is used to mark a class or virtual function as final. */ -#if __cplusplus >= 201103L -#define GCC_FINAL final +/* C++11 adds the ability to add "override" after an implementation of a + virtual function in a subclass, to: + (A) document that this is an override of a virtual function + (B) allow the compiler to issue a warning if it isn't (e.g. a mismatch + of the type signature). + + Similarly, it allows us to add a "final" to indicate that no subclass + may subsequently override the vfunc. + + Provide OVERRIDE and FINAL as macros, allowing us to get these benefits + when compiling with C++11 support, but without requiring C++11. + + For gcc, use "-std=c++11" to enable C++11 support; gcc 6 onwards enables + this by default (actually GNU++14). */ + +#if __cplusplus >= 201103 +/* C++11 claims to be available: use it. final/override were only + implemented in 4.7, though. */ +# if GCC_VERSION < 4007 +# define OVERRIDE +# define FINAL +# else +# define OVERRIDE override +# define FINAL final +# endif #elif GCC_VERSION >= 4007 -#define GCC_FINAL __final +/* G++ 4.7 supports __final in C++98. */ +# define OVERRIDE +# define FINAL __final #else -#define GCC_FINAL +/* No C++11 support; leave the macros empty: */ +# define OVERRIDE +# define FINAL #endif #ifdef __cplusplus |