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SubjectRe: checkpatch.pl: Wrong check SINGLE_STATEMENT_DO_WHILE_MACRO
On Thu, Aug 02, 2012 at 10:00:04AM +0200, Schrober wrote:
> Hi,
>
> I think your check for SINGLE_STATEMENT_DO_WHILE_MACRO is wrong. Just to give
> an example:
>
> #define foobar(x) \
> do { \
> if (pizza_ready(x)) \
> eat_pizza(x); \
> } while (0)
>
>
> if (hungry(y))
> foobar(x);
> else
> barfoo(x);
>
> checkpatch does now complain about something like "WARNING: Single statement
> macros should not use a do {} while (0) loop"
>
> But we would have an ambiguous else when the do-while is removed. The code
> works as expected with the do-while but the else is "attached" to the wrong
> "if" when the do-while is removed.
>
> And yes, this example is made that easy to make it easy to understand. There
> are examples were static inline code would not work very well (vararg for
> example).
>
> Please fix or remove your check. Otherwise some people will be start to
> overeagerly change these macros and break the kernel doing that.

It does appear this check should not apply when a control statement is
included.

-apw


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