diff options
| author | Michael Weghorn <m.weghorn@posteo.de> | 2025-12-04 14:56:53 +0100 |
|---|---|---|
| committer | Michael Weghorn <m.weghorn@posteo.de> | 2025-12-08 20:11:39 +0100 |
| commit | 0fbff78f57b3a642d4ab95f35f08d779507122ed (patch) | |
| tree | 08a57be4e8dbb66c23a96c9fe90240fe97285750 /src | |
| parent | dce9a1c596b4fa38b46e199735464660ad0c55bc (diff) | |
a11y: Ensure std::memcmp works by adding member for unused State bits
Due to padding, std::memcmp wasn't guaranteed to return 0
even if all (bit)fields of the two QAccessible::State
structs were identical.
This was e.g. causing various of the state-related tests
in tst_qaccessibility to fail in a Clang 21 build on Debian
testing.
Prevent randomness in the padding bits by making them explicit
using an explicit `qt_reserved` member.
All bits are already initialized to 0 in the ctor and
now updating another field can no longer result in random
values being written to the previously unreserved bits.
Fixes: QTBUG-142463
Pick-to: 6.11 6.10 6.8 6.5
Change-Id: Id62866a688d8e8dd13143961b1a22f36cac09caa
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Diffstat (limited to 'src')
| -rw-r--r-- | src/gui/accessible/qaccessible_base.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/gui/accessible/qaccessible_base.h b/src/gui/accessible/qaccessible_base.h index 3881c6346a0..04efeddf06f 100644 --- a/src/gui/accessible/qaccessible_base.h +++ b/src/gui/accessible/qaccessible_base.h @@ -175,11 +175,15 @@ public: // quint64 alertMedium : 1; // quint64 alertHigh : 1; + Q_DECL_UNUSED_MEMBER quint64 qt_reserved : 27; + State() { std::memset(this, 0, sizeof(State)); } friend inline bool operator==(const QAccessible::State &first, const QAccessible::State &second) { + static_assert(std::has_unique_object_representations_v<State>, + "memcmp() cannot be used on types with padding"); return std::memcmp(&first, &second, sizeof(QAccessible::State)) == 0; } }; |