Re: [PATCH v4 0/2] Replaced locks with lock guard macros

[Stefan Hajnoczi]

On Fri, Mar 20, 2020 at 06:43:23AM -0700, address@hidden wrote:
> /tmp/qemu-test/src/util/thread-pool.c:213:5: error: unused variable 
> 'qemu_lockable_auto1' [-Werror,-Wunused-variable]
>     QEMU_LOCK_GUARD(&pool->lock);
>     ^
> /tmp/qemu-test/src/include/qemu/lockable.h:173:29: note: expanded from macro 
> 'QEMU_LOCK_GUARD'

Apparently gcc suppresses "unused variable" warnings with g_autoptr() so
we didn't see this warning before.

clang does report them so let's silence the warning manually.  Please
add G_GNUC_UNUSED onto the g_autoptr variable definition in the
QEMU_LOCK_GUARD() macro:

  #define QEMU_LOCK_GUARD(x) \
      g_autoptr(QemuLockable) qemu_lockable_auto##__COUNTER__ G_GNUC_UNUSED = \
              qemu_lockable_auto_lock(QEMU_MAKE_LOCKABLE((x)))

The WITH_*_LOCK_GUARD() macros should not require changes because the
variable is both read and written.

You can test locally by building with clang (llvm) instead of gcc:

  ./configure --cc=clang

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