* fix: avoid an implicit cast
The "1" used for the bitshift is treated as int, and this causes an
implicit conversion to `UInt` when performing the logical and.
Explicitly casting the number to `UInt` avoids the warning.
* fix: avoid implicit conversions for indices
Some indices in `include/fmt/base.h` are expressed as `int` types, which
causes an implicit conversion to a `size_t` when they are actually used
as index. Explicitly casting the value avoids the warning.
* fix: avoid an implicit conversion using size_t
The number of bits is used to express the size of a buffer. Using an
`int` causes an implicit conversion warning, let's use a `size_t` which
is the right type for the job.
ea985e84f8