Update ei_x_encode_long documentation to indicate variable length encoding.

[mpope9]

The ei_x_encode_long function does not encode the passed value to the fixed length of a long. Updating the documentation to make that more obvious.

[CLAassistant]

All committers have signed the CLA.

[github-actions]

CT Test Results

Tests are running... https://github.com/erlang/otp/actions/runs/7935778611

Results for commit 463f918

To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass.

See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally.

Artifacts

• No CT logs found
• No HTML docs found
• No Windows Installer found

// Erlang/OTP Github Action Bot

[jhogberg]

Thanks for the PR! I think this note would be better in the module description, as it makes it clearer that we don't promise that any of these functions encode to a fixed length.

[mpope9]

Thanks! That makes sense, will make that change.

[jhogberg]

I think belongs more in the paragraph above. How about something like?

All encode functions assume that the `buf` and `index` parameters point to a
buffer large enough for the data. Note that the binary term format uses variable-
length encoding so different values can require a different amount of space. For
example, smaller integer values can be more compact than larger ones. To get
the size of an encoded term, without encoding it, pass `NULL` instead of a
buffer pointer. Parameter `index` is incremented, but nothing will be encoded.
This is the way in `ei` to "preflight" term encoding.

[mpope9]

I think it is much more clear. I didn't want to include the integer example directly incase it changes in the future but it is a good example. Will make this change.

[jhogberg]

Great, I think the bit about "The ei_x_ encode functions do not guarantee
the final buffer length, expect variable length buffers." is a bit redundant given the paragraph above. Please remove that and squash the commits, and then I'll merge this straight away. :-)

[jhogberg]

Merged, thanks again for the PR!