Re: Possible code defects: macros and precedence

Julia Lawall
2016-09-04T10:10:28Z

On Sat, 3 Sep 2016, Joe Perches wrote:

> There are many nominally incorrect macro definitions
> in linux-kernel source where parentheses are not used
> for various macros arguments with calculations.
>
> Does coccinelle or smatch have the ability to detect
> potential macro misuse where arguments passed to the
> macro are not correctly parenthesized by the macro?
>
> Something like:
>
> #define A 1
> #define B 2
> #define shift(val) (val << 1)
>
> where a use is:
>
> int c = shift(A | B)
>
> where the actual result is 5 but the expected result is 6?
>
> Can either tool suggest changing the macro to
>
> #define shift(val) ((val) << 1)

Coccinelle could do this. It is possible to match macro parameters, and
it is possible to match binary operators generically. I can look into it.

julia