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documentation: update CodingStyle on local variables naming in macros 

Describe proper naming convention for local variables in macros
resembling functions.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bartosz Golaszewski 2015-04-16 12:43:31 -07:00 committed by Linus Torvalds
parent 95d119528b
commit f2027543b9
1 changed files with 13 additions and 0 deletions
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Documentation/CodingStyle
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@ -659,6 +659,19 @@ macros using parameters.
#define CONSTANT 0x4000
#define CONSTEXP (CONSTANT | 3)
5) namespace collisions when defining local variables in macros resembling
functions:
#define FOO(x) \
({ \
typeof(x) ret; \
ret = calc_ret(x); \
(ret); \
)}
ret is a common name for a local variable - __foo_ret is less likely
to collide with an existing variable.
The cpp manual deals with macros exhaustively. The gcc internals manual also
covers RTL which is used frequently with assembly language in the kernel.