node-api: add napi_float16_array

[bnoordhuis]

Fixes: #58873

[nodejs-github-bot]

Review requested:

• @nodejs/node-api

[legendecas]

There is an open PR for this: #58879

[jasnell]

Duplicates #58879

[bnoordhuis]

The other guy should have back-linked to the issue... from a quick glance, that PR breaks ABI; this one doesn't.

[jasnell]

Ok, the other PR can be updated to fix any remaining issues. I'd encourage providing review comments and suggestions there.

[bnoordhuis]

Why? This one is perfect. It's not first come, first serve, right?

[legendecas]

Without breaking the ABI, we still need to mark this as NAPI_EXPERIMENTAL as mentioned in #58879 (comment) until this is been backported to all LTS lines.

In addition, we need a feature macro, to allow addons to detect a new feature: https://github.com/nodejs/node/blob/main/doc/contributing/adding-new-napi-api.md#process-and-approval.

[addaleax]

Without breaking the ABI

The problem with this in #58879 was that the enum value was added in the middle. Adding an extra enum value at the end, as it is done here, is generally not ABI-breaking since it does not change the numeric values of the other enum alternatives.

[legendecas]

I'm not saying this breaks ABI. My point is we need guard this with NAPI_EXPERIMENTAL (and a NAPI_VERSION bump soon in the next versions) and a feature macro to allow addons detect that APIs like napi_create_typedarray are supported with napi_float16_array at both build time and run time.

[jasnell]

Certainly not first come first serve but there's also no harm at all in helping a newer contributor work through any remaining issues in their PR. And as @legendecas points out there are outstanding issues in the PR also.

[legendecas]

Thank you very much for the patch! Still, we have #58879 landed.