> Do not use for loop initial declarations
> Variadic macros are acceptable, but remember
Maybe my brain is too smooth, but I don't understand how for(int i = 0...) is too clever but variadic macros are not. That makes no sense to me.
> Variadic macros are acceptable, but remember
Maybe my brain is too smooth, but I don't understand how for(int i = 0...) is too clever but variadic macros are not. That makes no sense to me.
I think the no "loop initial declarations" is for consistency with "all declarations at the top". Other coding style guides favor "declarations as close as possible to first use", including guidelines for mission critical systems (if you resort to argument from authority I have some too...) [1].
As much as I like Suckless, this section is just pet peeves that can safely be ignored; unless you submit a patch to a project that aligns with it.
True and it would indeed be desirable that it were. Here I go out on a limb and assume it's because someone got bitten by attempting to use the loop index outside the loop (common for search operations) while declaring the index within and outside the loop. A bug (gcc and clang can warn about using -Wshadow, but which sadly isn't part of -Wall) which might easily occur when multiple people edit the code over a longer time-span.
Why not force c90 altogether then?
An example of such a macro is the following macro (the loop and the variable declaration will both be optimized out by the compiler; I have tested this):
#define lpt_document() for(int lpt_document_=lpt_begin();lpt_document_;lpt_document_=(lpt_end(),0))
#define win_form(xxx) for(win_memo win_mem=win_begin_();;win_step_(&win_mem,xxx))