Re: [libvirt] [PATCH 4/4] cpu: Avoid c99 style of assembler

On Thu, Apr 27, 2017 at 09:22:04AM +0100, Daniel P. Berrange wrote: Looking at the gcc/clang docs... By default GCC applies a C standard called gnu89/gnu90, which is basically c89/c90, but with a tonne of GCC extensions, many of which are present in the newer c99. Actually using c89 is impractical since it lacks even basic things like "inline" and var-args for macros. CLang aims to be compatible with GCC extensions, but in fact defaults to the even newer gnu11 standard, which is C11 + GCC extensions It looks like the only GCC extensions we rely on from gnu89, are all present in c99 - at least build succeeds with both std=gnu89 and std=c99 So, it is probably accurate to say we're compliant with c99, and if a compiler doesn't support c99, it must support the GNU extensions to c89. In practice we only care about GCC & CLang. So I guess the question from thsi patch series is mostly, which c99 features do we wish to explicitly avoid using. Variable declarations in the middle of blocks is one we avoid, just because it harms readability and understanding of code when goto is just to jump over a variable declaration. I see no problem using c99 asm statements, unless we're using a mix of different asm syntaxes across the code base, in which case we should standardize on one. I tend to think it is worth avoiding C++ comments, just for sake of having a consistent style across the code base. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|