[ros-dev] [ros-diffs] [cgutman] 44286: - Initialize SocketError to 0 to prevent a bogus error from GCC

Sarocet sarocet at gmail.com
Thu Nov 26 00:23:54 CET 2009


Alex Ionescu wrote:
> No they are correct, most of the times the "may" means "given certain code paths", not "may" as in "uhhh... I think it could happen?"
>
> The reason the error often happens, with GCC *AND* MSVC (see previous e-mail) is stuff like this:
>
> BOOLEAN HaveYourDad;
> PVOID Pen15;
> ULONG YourMom;
>
> if (YourMom)
> {
>      Pen15 = ExAllocateYourDad();
>      HaveYourDad = TRUE;
> }
>
> ....
>
>
> if (HaveYourDad) ExReleaseYourDad(Pen15);
>
> In this case, the compiler might say that your Pen15 may be used without having been initialized because it doesn't realize that I'm only going to have your dad if I also already had your mom.
>
> Had you written:
>
> if (YourMom) ExReleaseYourDad(Pen15); the compiler would probably be smart enough to realize the side-effect.  
>   
You can't always simplify it by having a YourMum equivalent to HaveYourDad.
It's a pity that compilers don't provide a way to link Pen15 to
HaveYourDad. With such a hint they could realise that Pen15 is not being
used uninitialised there, while checking for usages not into a 
HaveYourDad conditional (as well as warn you if you set HaveYourDad and
Pen15 isn't set on that branch).




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