Messages in this thread | | | Date | Sun, 12 Mar 2023 16:23:48 +0200 | Subject | Re: [PATCH] staging: iio: meter: enclose Macros with complex values in parentheses | From | Menna Mahmoud <> |
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On ١٢/٣/٢٠٢٣ ١٦:١٢, Julia Lawall wrote: > > On Sun, 12 Mar 2023, Menna Mahmoud wrote: > >> enclose Macros with complex values in parentheses is especially useful >> in making macro definitions “safe” (so that they >> evaluate each operand exactly once). > enclose -> Enclose, and Macros -> macros > > I don't understand the above comment though. How does adding parentheses > around the body of a macro cause the operands to be evaluated only once? > And the macros that you have changed don't have any operands. > > The value of adding parentheses is normally to ensure that the body of the > macro doesn't interact with the context in a weird way. For example, you > could have > > #define ADD 3 + 4 > > Then if you use your macro as 6 * ADD, you will end up evaluating > 6 * 3 + 4, ie 18 + 4, when you might have expected 6 * 7. The issue is > that * has higher precedence than +.
yes, I mean that but i couldn't explain it well, thanks for your feedback.
> > But I don't think that such a problem can arise with a cast expression, so > parentheses around it should not be necessary.
So, no need for this patch?
>> this error reported by chechpatch.pl > this error is reported by checkpatch. > >> "ERROR: Macros with complex values should be enclosed in parentheses" >> >> for ADE7854_SPI_SLOW, ADE7854_SPI_BURST and ADE7854_SPI_FAST >> macros and this error fixed by enclose these macros in parentheses. > The last two lines aren't needed. One can easily see that from looking at > the patch.
Got it, Thank you.
Menna
> julia > >> Signed-off-by: Menna Mahmoud <eng.mennamahmoud.mm@gmail.com> >> --- >> drivers/staging/iio/meter/ade7854.h | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/staging/iio/meter/ade7854.h b/drivers/staging/iio/meter/ade7854.h >> index 7a49f8f1016f..41eeedef569b 100644 >> --- a/drivers/staging/iio/meter/ade7854.h >> +++ b/drivers/staging/iio/meter/ade7854.h >> @@ -139,9 +139,9 @@ >> #define ADE7854_MAX_RX 7 >> #define ADE7854_STARTUP_DELAY 1000 >> >> -#define ADE7854_SPI_SLOW (u32)(300 * 1000) >> -#define ADE7854_SPI_BURST (u32)(1000 * 1000) >> -#define ADE7854_SPI_FAST (u32)(2000 * 1000) >> +#define ADE7854_SPI_SLOW ((u32)(300 * 1000)) >> +#define ADE7854_SPI_BURST ((u32)(1000 * 1000)) >> +#define ADE7854_SPI_FAST ((u32)(2000 * 1000)) >> >> /** >> * struct ade7854_state - device instance specific data >> -- >> 2.34.1 >> >> > >
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