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Markus Armbruster bb71846325 qobject atomics osdep: Make a few macros more hygienic 
Variables declared in macros can shadow other variables.  Much of the
time, this is harmless, e.g.:

    #define _FDT(exp)                                                  \
        do {                                                           \
            int ret = (exp);                                           \
            if (ret < 0) {                                             \
                error_report("error creating device tree: %s: %s",   \
                        #exp, fdt_strerror(ret));                      \
                exit(1);                                               \
            }                                                          \
        } while (0)

Harmless shadowing in h_client_architecture_support():

        target_ulong ret;

        [...]

        ret = do_client_architecture_support(cpu, spapr, vec, fdt_bufsize);
        if (ret == H_SUCCESS) {
            _FDT((fdt_pack(spapr->fdt_blob)));
            [...]
        }

        return ret;

However, we can get in trouble when the shadowed variable is used in a
macro argument:

    #define QOBJECT(obj) ({                                 \
        typeof(obj) o = (obj);                              \
        o ? container_of(&(o)->base, QObject, base) : NULL; \
     })

QOBJECT(o) expands into

    ({
--->    typeof(o) o = (o);
        o ? container_of(&(o)->base, QObject, base) : NULL;
    })

Unintended variable name capture at --->.  We'd be saved by
-Winit-self.  But I could certainly construct more elaborate death
traps that don't trigger it.

To reduce the risk of trapping ourselves, we use variable names in
macros that no sane person would use elsewhere.  Here's our actual
definition of QOBJECT():

    #define QOBJECT(obj) ({                                         \
        typeof(obj) _obj = (obj);                                   \
        _obj ? container_of(&(_obj)->base, QObject, base) : NULL;   \
    })

Works well enough until we nest macro calls.  For instance, with

    #define qobject_ref(obj) ({                     \
        typeof(obj) _obj = (obj);                   \
        qobject_ref_impl(QOBJECT(_obj));            \
        _obj;                                       \
    })

the expression qobject_ref(obj) expands into

    ({
        typeof(obj) _obj = (obj);
        qobject_ref_impl(
            ({
--->            typeof(_obj) _obj = (_obj);
                _obj ? container_of(&(_obj)->base, QObject, base) : NULL;
            }));
        _obj;
    })

Unintended variable name capture at --->.

The only reliable way to prevent unintended variable name capture is
-Wshadow.

One blocker for enabling it is shadowing hiding in function-like
macros like

     qdict_put(dict, "name", qobject_ref(...))

qdict_put() wraps its last argument in QOBJECT(), and the last
argument here contains another QOBJECT().

Use dark preprocessor sorcery to make the macros that give us this
problem use different variable names on every call.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230921121312.1301864-8-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
 		2023-09-29 08:13:57 +02:00
..
accel.h typedefs: Forward-declare AccelState 2023-01-06 00:50:32 +01:00
async-teardown.h Don't include headers already included by qemu/osdep.h 2023-02-08 07:28:05 +01:00
atomic.h qobject atomics osdep: Make a few macros more hygienic 2023-09-29 08:13:57 +02:00
atomic128.h include/qemu: Move CONFIG_ATOMIC128_OPT handling to atomic128.h 2023-05-23 16:51:18 -07:00
base64.h nomaintainer: Fix Lesser GPL version number 2020-11-15 17:04:40 +01:00
bcd.h
…
bitmap.h replace TABs with spaces 2023-03-20 12:43:50 +01:00
bitops.h qemu/bitops.h: Limit rotate amounts 2023-05-02 12:36:46 -07:00
bswap.h bswap: Add the ability to store to an unaligned 24 bit field 2023-06-22 18:55:14 -04:00
buffer.h Replace GCC_FMT_ATTR with G_GNUC_PRINTF 2022-03-22 14:40:51 +04:00
cacheflush.h util: Enhance flush_icache_range with separate data pointer 2021-01-07 05:09:41 -10:00
cacheinfo.h include: Move qemu_[id]cache_* declarations to new qemu/cacheinfo.h 2022-02-21 13:30:20 +00:00
clang-tsa.h clang-tsa: Add macros for shared locks 2022-12-15 16:07:43 +01:00
co-shared-resource.h co-shared-resource: protect with a mutex 2021-06-25 14:24:24 +03:00
compiler.h qobject atomics osdep: Make a few macros more hygienic 2023-09-29 08:13:57 +02:00
config-file.h qemu-config: Make config_parse_qdict() return bool 2022-12-14 16:19:35 +01:00
coroutine-core.h coroutine: Split qemu/coroutine-core.h off qemu/coroutine.h 2023-01-20 07:21:46 +01:00
coroutine-tls.h tls: add macros for coroutine-safe TLS variables 2022-03-04 18:14:40 +01:00
coroutine.h coroutine: Split qemu/coroutine-core.h off qemu/coroutine.h 2023-01-20 07:21:46 +01:00
coroutine_int.h coroutine: support SafeStack in ucontext backend 2020-06-23 15:46:05 +01:00
cpu-float.h Clean up ill-advised or unusual header guards 2022-05-11 16:50:01 +02:00
cpuid.h host/include/i386: Implement clmul.h 2023-09-15 13:57:00 +00:00
crc-ccitt.h bulk: Do not declare function prototypes using 'extern' keyword 2023-08-31 19:47:43 +02:00
crc32c.h igb: Implement Rx SCTP CSO 2023-05-23 15:20:15 +08:00
ctype.h qemu-common: Move qemu_isalnum() etc. to qemu/ctype.h 2019-06-11 20:22:09 +02:00
cutils.h cutils: Adjust signature of parse_uint[_full] 2023-06-02 12:27:19 -05:00
datadir.h vl: extract softmmu/datadir.c 2020-12-10 12:15:18 -05:00
dbus.h Don't include headers already included by qemu/osdep.h 2023-02-08 07:28:05 +01:00
drm.h Clean up ill-advised or unusual header guards 2019-05-13 08:58:55 +02:00
envlist.h remove unnecessary extern "C" blocks 2023-02-10 14:12:06 +01:00
error-report.h Move error_printf_unless_qmp() with monitor unit 2022-04-21 17:09:09 +04:00
event_notifier.h event_notifier: add event_notifier_get_wfd() 2022-03-06 06:19:47 -05:00
fifo8.h util/fifo8: Fix typo in fifo8_push_all() description 2023-08-31 19:47:43 +02:00
fifo32.h
…
filemonitor.h nomaintainer: Fix Lesser GPL version number 2020-11-15 17:04:40 +01:00
futex.h
…
guest-random.h util: Add qemu_guest_getrandom and associated routines 2019-05-22 12:38:54 -04:00
hbitmap.h hbitmap: fix hbitmap_status() return value for first dirty bit case 2023-02-17 14:34:24 +01:00
help-texts.h Update copyright dates to 2023 2023-05-30 15:50:17 +01:00
help_option.h keyval: Parse help options 2020-10-15 16:06:27 +02:00
host-utils.h host-utils: Add muldiv64_round_up 2023-09-06 11:19:33 +02:00
hw-version.h include: Move hardware version declarations to new qemu/hw-version.h 2022-02-21 13:30:20 +00:00
id.h net: Use id_generate() in the network subsystem, too 2021-03-09 21:47:45 +01:00
int128.h meson: Split test for __int128_t type from __int128_t arithmetic 2023-05-30 09:51:11 -07:00
interval-tree.h util: Add interval-tree.c 2022-12-20 17:09:41 -08:00
iov.h util/iov: Remove qemu_iovec_init_extended() 2023-06-05 13:11:24 +02:00
iova-tree.h util: spelling fixes 2023-08-31 19:47:43 +02:00
jhash.h Clean up ill-advised or unusual header guards 2019-05-13 08:58:55 +02:00
job.h job: remove unused functions 2022-10-07 12:11:41 +02:00
keyval.h Clean up ill-advised or unusual header guards 2022-05-11 16:50:01 +02:00
lockable.h coroutine: Split qemu/coroutine-core.h off qemu/coroutine.h 2023-01-20 07:21:46 +01:00
log-for-trace.h util/log: Drop return value from qemu_log 2022-04-20 10:51:11 -07:00
log.h util/log: Add vector registers to log 2023-06-13 17:42:01 +10:00
madvise.h include: Move qemu_madvise() and related #defines to new qemu/madvise.h 2022-02-21 13:30:20 +00:00
main-loop.h async: Add an optional reentrancy guard to the BH API 2023-04-28 11:31:07 +02:00
memalign.h osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
memfd.h linux-user: add memfd_create 2019-09-11 08:46:17 +02:00
mmap-alloc.h util/mmap-alloc: qemu_fd_getfs() 2023-04-24 11:29:00 +02:00
module.h module: add Error arguments to module_load and module_load_qom 2022-11-06 09:48:50 +01:00
mprotect.h include: Move qemu_mprotect_*() to new qemu/mprotect.h 2022-02-21 13:30:20 +00:00
notify.h xen / notify: introduce a new XenWatchList abstraction 2019-09-24 12:18:47 +01:00
nvdimm-utils.h Clean up includes 2020-12-10 17:16:44 +01:00
option.h include: add qemu/keyval.h 2022-04-21 17:03:51 +04:00
option_int.h qemu/queue.h: simplify reverse access to QTAILQ 2019-01-11 15:46:55 +01:00
osdep.h qobject atomics osdep: Make a few macros more hygienic 2023-09-29 08:13:57 +02:00
path.h
…
plugin-event.h include/qemu: Split out plugin-event.h 2023-03-22 15:06:57 +00:00
plugin-memory.h plugin: Simplify struct qemu_plugin_hwaddr 2023-09-16 14:57:15 +00:00
plugin.h include/qemu/plugin: Inline qemu_plugin_disable_mem_helpers 2023-03-22 15:06:57 +00:00
pmem.h Clean up decorations and whitespace around header guards 2019-05-13 08:58:55 +02:00
processor.h qemu/processor: Remove unused 'qemu/atomic.h' header 2023-08-31 19:47:43 +02:00
progress_meter.h coroutine: Clean up superfluous inclusion of qemu/lockable.h 2023-01-19 10:18:28 +01:00
qdist.h Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
qemu-plugin.h include/qemu: add documentation for memory callbacks 2023-03-22 15:06:57 +00:00
qemu-print.h Replace GCC_FMT_ATTR with G_GNUC_PRINTF 2022-03-22 14:40:51 +04:00
qemu-progress.h include: move progress API to qemu-progress.h 2022-04-06 14:31:43 +02:00
qht.h qht: constify qht_statistics_init 2018-09-26 08:55:54 -07:00
qsp.h qsp: Simplify how qsp_report() prints 2019-04-18 22:18:59 +02:00
qtree.h util: import GTree as QTree 2023-03-28 15:23:10 -07:00
queue.h qemu/atomic.h: rename atomic_ to qatomic_ 2020-09-23 16:07:44 +01:00
range.h compiler.h: replace QEMU_WARN_UNUSED_RESULT with G_GNUC_WARN_UNUSED_RESULT 2022-03-22 14:40:51 +04:00
ratelimit.h ratelimit: treat zero speed as unlimited 2021-06-25 14:22:21 +03:00
rcu.h bulk: Do not declare function prototypes using 'extern' keyword 2023-08-31 19:47:43 +02:00
rcu_queue.h remove unnecessary extern "C" blocks 2023-02-10 14:12:06 +01:00
readline.h readline: Extract readline_add_completion_of() from monitor 2023-02-04 07:56:54 +01:00
selfmap.h util/selfmap: Use dev_t and ino_t in MapInfo 2023-09-01 13:34:03 -07:00
seqlock.h qemu/atomic.h: rename atomic_ to qatomic_ 2020-09-23 16:07:44 +01:00
sockets.h osdep: implement qemu_socketpair() for win32 2023-03-13 15:39:31 +04:00
stats64.h stat64: Add stat64_set() operation 2023-04-27 16:39:43 +02:00
sys_membarrier.h bulk: Do not declare function prototypes using 'extern' keyword 2023-08-31 19:47:43 +02:00
systemd.h Normalize header guard symbol definition. 2019-05-13 08:58:55 +02:00
thread-context.h util: Introduce ThreadContext user-creatable object 2022-10-27 11:00:43 +02:00
thread-posix.h thread-posix: implement Semaphore with QemuCond and QemuMutex 2022-04-06 14:31:56 +02:00
thread-win32.h util: Use real functions for thread-posix QemuRecMutex 2021-06-16 15:03:26 +02:00
thread.h util/qemu-thread-posix: use TSA_NO_TSA to suppress clang TSA warnings in FreeBSD 2023-02-17 11:22:19 +01:00
throttle-options.h
…
throttle.h throttle: use enum ThrottleDirection instead of bool is_write 2023-08-29 10:49:24 +02:00
timed-average.h
…
timer.h qemu/timer: Add host ticks function for RISC-V 2023-09-21 10:39:51 +02:00
transactions.h transactions: Invoke clean() after everything else 2021-11-16 09:43:44 +01:00
tsan.h include/qemu: Added tsan.h for annotations. 2020-06-16 14:49:05 +01:00
typedefs.h accel/tcg: Simplify tlb_plugin_lookup 2023-09-16 14:57:15 +00:00
unicode.h json: Reject invalid UTF-8 sequences 2018-08-24 20:26:37 +02:00
units.h block: Eliminate the S_1KiB, S_2KiB, ... macros 2019-02-01 13:46:45 +01:00
uri.h bulk: Do not declare function prototypes using 'extern' keyword 2023-08-31 19:47:43 +02:00
userfaultfd.h migration: Clean up includes 2023-02-08 07:27:20 +01:00
uuid.h qemu/uuid: Add UUID static initializer 2023-03-02 19:13:52 -05:00
vfio-helpers.h util/vfio-helpers: Pass Error handle to qemu_vfio_dma_map() 2021-09-07 09:08:24 +01:00
vhost-user-server.h io: follow coroutine AioContext in qio_channel_yield() 2023-09-07 20:32:11 -05:00
win_dump_defs.h include/qemu: add 32-bit Windows dump structures 2022-04-22 13:36:04 +04:00
xattr.h qemu/xattr.h: Exclude <sys/xattr.h> for Windows 2022-12-23 11:48:13 +01:00
xxhash.h accel/tcg: include cs_base in our hash calculations 2023-06-01 11:05:05 -04:00
yank.h util: spelling fixes 2023-08-31 19:47:43 +02:00