riscv/qemu: QEMU main repository: Please see https://www.qemu.org/docs/master/devel/submitting-a-patch.html for how to submit changes to QEMU. Pull Requests are ignored. Please only use release tarballs from the QEMU website. http://www.qemu.org - qemu

QEMU main repository: Please see https://www.qemu.org/docs/master/devel/submitting-a-patch.html for how to submit changes to QEMU. Pull Requests are ignored. Please only use release tarballs from the QEMU website. http://www.qemu.org

emulation kvm qemu virtualization

History

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>		3 years ago
..
qmp	qobject atomics osdep: Make a few macros more hygienic	3 years ago
clone-visitor.h	qapi: Make visitor functions taking Error ** return bool, not void	6 years ago
compat-policy.h	qapi: Factor out compat_policy_input_ok()	5 years ago
dealloc-visitor.h	include: Fix typos found by codespell	9 years ago
error.h	error: add global &error_warn destination	3 years ago
forward-visitor.h	qapi: introduce forwarding visitor	5 years ago
opts-visitor.h	Move include qemu/option.h from qemu-common.h to actual users	8 years ago
qmp-event.h	qapi: Eliminate indirection through qmp_event_get_func_emit()	7 years ago
qobject-input-visitor.h	qapi: Move compat policy from QObject to generic visitor	5 years ago
qobject-output-visitor.h	qapi: Move compat policy from QObject to generic visitor	5 years ago
string-input-visitor.h	qapi: Rewrite string-input-visitor's integer and list parsing	7 years ago
string-output-visitor.h	qapi: Add new visit_complete() function	10 years ago
type-helpers.h	monitor: introduce HumanReadableText and HMP support	4 years ago
util.h	qapi: Extend -compat to set policy for unstable interfaces	5 years ago
visitor-impl.h	qapi: Generalize struct member policy checking	5 years ago
visitor.h	qapi: Generalize struct member policy checking	5 years ago