Re: Patch to use aes_*_ctr in newer versions of OpenSSL and #if LIBSSH2_DSA for more DSA-code

On Mon, 1 Mar 2010, Simon Josefsson wrote:

>> Ah, yes it was a warning only, the error must've been some mistake of mine.
>> I like -Wundef because it makes you write stricter code that leaves less
>> mistakes around. Like when you do #if [misspelled define] which always will
>> evaluate false but with -Wundef will give you a clear warning. That
>> specific mistake is also very hard to spot and track down (and yes I've
>> seen it happen more than once).
>
> I understand, and I've seen that too. There are disadvantages though: if
> someone declares the constant to 0 and expects the feature to be disabled.
> Further, it encourages adding defined-checks to all CPP symbols regardless
> of how they are intended to be used. I've seen these two patterns cause
> problems more than once as well.

Yes, as a consequence of the above I think enabling and disabling features in
code should be done with #ifdef and #define/#undef, and not #if and #define
[variable] 0/1.

> Anyway, this is an aesthetic discussion. I believe discussing it helps
> to make us aware of the underlying trade-offs though.

Agreed!

-- 
  / daniel.haxx.se
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