The length is stored as the first byte in the output from
compile_line. As the data pointer is char, if char is signed then
length could be negative resulting in undefined behaviour. This
commit fixes the issue by reading and writing that byte as a
uint8_t.

This bug was caused by 2a00ca79f6.
Previously, the entries could only be a maximum of 128 bytes, and
would not be negative on platforms with signed chars. That
commit was made to support long emoji entries, especially for
non-Latin languages where the utf-8 representations could be
longer than 128 bytes.

This change also adds some documentation to make it clearer what
is going on. NOTE: The code should really be using actual struct
objects instead of writing to opaque char buffers.

Reported by Reef Turner <[email protected]>

Reported by Reef Turner <[email protected]>

This fixes the clang warning:

    comparison of unsigned expression < 0 is always false
    [-Wtautological-compare]

Reported by Reef Turner <[email protected]>

See ar_listx as an example.

This will prevent writing the file if the command fails.

The stdint.h is not included when building test, then including this module inside encoding.h

Deleted symbols/characters in it_lists now available in it_emoji