documentation: update CodingStyle on local variables naming in macros
authorBartosz Golaszewski <bgolaszewski@baylibre.com>
Thu, 16 Apr 2015 19:43:31 +0000 (12:43 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 17 Apr 2015 13:03:54 +0000 (09:03 -0400)
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>
Documentation/CodingStyle

index 449a8a19fc21fd12582e4ab144549740bd6dd4c3..4d4f06d47e0620325016bbda0af537995a8bfead 100644 (file)
@@ -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.