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Add utility macros for clang detection, and deprecation with messages.

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There are three new macros added to features.h and sys/cdefs.h:

 * __glibc_clang_prereq: just like __GNUC_PREREQ, but for clang.
 * __glibc_clang_has_extension: wraps clang's intrinsic __has_extension.
   Writing "#if defined __clang__ && __has_extension (...)" doesn't work,
   because compilers other than clang will object to the unknown macro
   __has_extension even though they don't need to evaluate it.
   Instead, write "#if __glibc_clang_has_extension (...)".

 * __attribute_deprecated_msg__(msg): like __attribute_deprecated__, but
   if possible, prints a message.

The first two are used to define the third.  The third will be used
in subsequent patches.

	* include/features.h (__glibc_clang_prereq): New macro.
	* misc/sys/cdefs.h (__glibc_clang_has_extension)
	(__attribute_deprecated_msg__): New macros.
This commit is contained in:
Zack Weinberg 2016-04-28 11:07:58 -04:00
parent bf91be88ea
commit cab4d74b01
3 changed files with 42 additions and 5 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2016-08-03 Zack Weinberg <zackw@panix.com>
* include/features.h (__glibc_clang_prereq): New macro.
* misc/sys/cdefs.h (__glibc_clang_has_extension)
(__attribute_deprecated_msg__): New macros.
2016-08-03 Joseph Myers <joseph@codesourcery.com>
* bits/libc-header-start.h (__GLIBC_USE_IEC_60559_BFP_EXT): New

19
include/features.h
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@ -138,13 +138,13 @@
# define __KERNEL_STRICT_NAMES
#endif
/* Convenience macros to test the versions of glibc and gcc.
Use them like this:
/* Convenience macro to test the version of gcc.
Use like this:
#if __GNUC_PREREQ (2,8)
... code requiring gcc 2.8 or later ...
#endif
Note - they won't work for gcc1 or glibc1, since the _MINOR macros
were not defined then. */
Note: only works for GCC 2.0 and later, because __GNUC_MINOR__ was
added in 2.0. */
#if defined __GNUC__ && defined __GNUC_MINOR__
# define __GNUC_PREREQ(maj, min) \
((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
@ -152,6 +152,17 @@
# define __GNUC_PREREQ(maj, min) 0
#endif
/* Similarly for clang. Features added to GCC after version 4.2 may
or may not also be available in clang, and clang's definitions of
__GNUC(_MINOR)__ are fixed at 4 and 2 respectively. Not all such
features can be queried via __has_extension/__has_feature. */
#if defined __clang_major__ && defined __clang_minor__
# define __glibc_clang_prereq(maj, min) \
((__clang_major__ << 16) + __clang_minor__ >= ((maj) << 16) + (min))
#else
# define __glibc_clang_prereq(maj, min) 0
#endif
/* Whether to use feature set F. */
#define __GLIBC_USE(F) __GLIBC_USE_ ## F

22
misc/sys/cdefs.h
View File

@ -77,6 +77,15 @@
#endif /* GCC. */
/* Compilers that are not clang may object to
#if defined __clang__ && __has_extension(...)
even though they do not need to evaluate the right-hand side of the &&. */
#if defined __clang__ && defined __has_extension
# define __glibc_clang_has_extension(ext) __has_extension (ext)
#else
# define __glibc_clang_has_extension(ext) 0
#endif
/* These two macros are not used in glibc anymore. They are kept here
only because some other projects expect the macros to be defined. */
#define __P(args) args
@ -249,13 +258,24 @@
# define __attribute_noinline__ /* Ignore */
#endif
/* gcc allows marking deprecated functions. */
/* Since version 3.2, gcc allows marking deprecated functions. */
#if __GNUC_PREREQ (3,2)
# define __attribute_deprecated__ __attribute__ ((__deprecated__))
#else
# define __attribute_deprecated__ /* Ignore */
#endif
/* Since version 4.5, gcc also allows one to specify the message printed
when a deprecated function is used. clang claims to be gcc 4.2, but
may also support this feature. */
#if __GNUC_PREREQ (4,5) || \
__glibc_clang_has_extension (__attribute_deprecated_with_message__)
# define __attribute_deprecated_msg__(msg) \
__attribute__ ((__deprecated__ (msg)))
#else
# define __attribute_deprecated_msg__(msg) __attribute_deprecated__
#endif
/* At some point during the gcc 2.8 development the `format_arg' attribute
for functions was introduced. We don't want to use it unconditionally
(although this would be possible) since it generates warnings.