style: cpp indentation

Joel Sherrill joel.sherrill at
Thu May 29 22:14:18 UTC 2014

On 5/29/2014 3:47 PM, Gedare Bloom wrote:
> Hi,
> Any guidance on whether we should have a style rule about CPP
> directives? Mainly this is for #ifdef #endif guards for conditional
> code compilation. There are two options based on what exists in the
> cpukit today:
> 1) Preprocessor directives within indented code should be one nesting
> level outside of the affected code.
> 2) Preprocessor directives within indented code should not be indented.
> You can see an example of both, e.g. at
> cpukit/score/src/threaddispatch.c:111-132 just to pick one.
(1) is historical
(2) is newer

Personally, I lean to (2) and may be the guilty party for much of that code.

Older C tended to always put the cpp #directives in the 1st column. Whether
there were broken compilers or we just followed K&R style, I don't know.

I think style (2) treats the conditionals like C logic and following the
same rules
seems to help.

But this is one of those things where I am sure I wrote in style (1) for
and somewhere was exposed to (2) and started using it.

FWIW The GNU Ada run-time for RTEMS should go back to the default of using
POSIX keys. That will fix it for SMP and eliminate some of this code.
> -Gedare
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Joel Sherrill, Ph.D.             Director of Research & Development
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