[U-Boot] [PATCH v3 0/16] Provide a mechanism to avoid using #ifdef everywhere

[Tom Rini]

On Tue, Feb 26, 2013 at 08:10:53AM -0800, Simon Glass wrote:

> Many parts of the U-Boot code base are sprinkled with #ifdefs. This makes
> different boards compile different versions of the source code, meaning
> that we must build all boards to check for failures. It is easy to misspell
> an #ifdef and there is not as much checking of this by the compiler. Multiple
> dependent #ifdefs are harder to do than with if..then..else. Variable
> declarations must be #idefed as well as the code that uses them, often much
> later in the file/function. #ifdef indents don't match code indents and
> have their own separate indent feature. Overall, excessive use of #idef
> hurts readability and makes the code harder to modify and refactor. For
> people coming newly into the code base, #ifdefs can be a big barrier.
> 
> The use of #ifdef in U-Boot has possibly got a little out of hand. In an
> attempt to turn the tide, this series includes a patch which provides a way
> to make CONFIG macros available to C code without using the preprocessor.
> This makes it possible to use standard C conditional features such as
> if/then instead of #ifdef. A README update exhorts compliance.

OK, this is true.  Looking over the series, a number of the patches are
just general fixes / improvements that don't depend on the autoconf_...
work.  Lets split this out now and take them in now as they seem like
reviewable by inspection code.

For the approach itself, I'm not sure which is best here.  In a lot of
cases we're trading an #ifdef for adding a level of indent to already
pretty indented code and that feels like a wash, in terms of readability
to me.  We probably need to re-factor some of the code in question there
too for readability, then see about using autoconf_... type things, or
maybe something else.

-- 
Tom
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