Unions are a C-reminiscense that are better avoided in modern C++.
They cause specific problems due to their nature of representing
independent types. The way they are used in Kaleidoscope, they
can easily be replaced by a class.
This enables it to properly work with Key objects in constexpr context
where with the old union-based implementation the compiler reported
errors when one Key was constructed based on a key_code/flags pair and
another one through raw-data. In such a case, the compiler assumes that
both Key instances represent something entirely different. This is
because unions were never meant for type conversions and the C++
standard considers their use for that purpose as undefined behavior.
The new class provides accessor methods for raw-data access and for
key_code/flags-data access.
This is a breaking change as it is is not possible to replace direct
member access patterns like
key.raw = 0xFFFF;
based on the raw-accessors.
For the .keyCode and .flags members, proxy objects are used
to enable the generation of suitable deprecations warnings.
All direct access via .raw, .keyCode and .flags have been replaced
throughout Kaleidoscope.
Information on how to upgrade is provided in UPGRADING.md
Signed-off-by: Florian Fleissner <florian.fleissner@inpartik.de>
Florian Fleissner
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