Re: [Emacs-diffs] master 6cd5678: Clarify compiler-pacifier in frame.c

[Paul Eggert <eggert@cs.ucla.edu>]

Eli Zaretskii wrote:

> This is backwards: it would mean we should use UNINIT all over the
> place just to be sure we will be able to spot some imaginary bugs by
> flipping a compiler switch.

That's not what UNINIT is for. It should be used only to pacify GCC. If GCC is 
happy with plain 'int x;' then UNINIT should not be used.

Furthermore, these use-before-set bugs are not "imaginary". In the typical case 
where GCC's -Wmaybe-uninitialized diagnostics are not false alarms, they are 
quite useful in spotting and fixing use-before-set bugs. I've fixed many that 
way myself, typically in my working copy as I develop code. Indeed, 'configure' 
enables -Wmaybe-uninitialized precisely because its utility outweighs its cost 
of a few false alarms and resulting need to use UNINIT or unnecessary 
initializations.

UNINIT can improve debugging, whereas unnecessary initializations can make the 
code look nicer. There's a tradeoff here, and different developers have 
different preferences of course. Developers who don't use tools that can take 
advantage of UNINIT may not appreciate or value its advantages.