sync_mixer() calls d->set_volume(d, &d->real_volume);
which makes v and &dev->real_volume point to the same memory area
and valgrind complains:
Source and destination overlap in memcpy(0xcc53e2c, 0xcc53e2c, 260)
at 0x488CFA0: __GI_memcpy (vg_replace_strmem.c:1121)
by 0xBB0803F: set_volume (acp.c:1143)
by 0xBB0EDCB: acp_device_set_port (acp.c:1897)
by 0xBA9CD87: impl_set_param (alsa-acp-device.c:757)
because the compiler apparently implicitly converts this into a memcpy()
and memcpy(3) explicitly says "The memory areas must not overlap."
bb29deb45a