Re: [PATCH] qemu/atomic.h: prefix qemu_ to solve <stdatomic.h> collisions

[Paolo Bonzini]

On 21/09/20 18:23, Stefan Hajnoczi wrote:
> clang's C11 atomic_fetch_*() functions only take a C11 atomic type
> pointer argument. QEMU uses direct types (int, etc) and this causes a
> compiler error when a QEMU code calls these functions in a source file
> that also included <stdatomic.h> via a system header file:
> 
>   $ CC=clang CXX=clang++ ./configure ... && make
>   ../util/async.c:79:17: error: address argument to atomic operation must be 
> a pointer to _Atomic type ('unsigned int *' invalid)
> 
> Avoid using atomic_*() names in QEMU's atomic.h since that namespace is
> used by <stdatomic.h>. Prefix QEMU's APIs with qemu_ so that atomic.h
> and <stdatomic.h> can co-exist.
> 
> This patch was generated using:
> 
>   $ git diff | grep -o '\<atomic_[a-z0-9_]\+' | sort -u 
> >/tmp/changed_identifiers
>   $ for identifier in $(</tmp/changed_identifiers64); do \
>        sed -i "s%\<$identifier\>%qemu_$identifier%" $(git grep -l 
> "\<$identifier\>") \
>     done

It's certainly a good idea but it's quite verbose.

What about using atomic__* as the prefix?  It is not very common in QEMU
but there are some cases (and I cannot think of anything better).

Paolo