POC: src: add addon ABI declaration option

[gabrielschulhof]

Add macro NODE_MODULE_DECLARE_ABI to give addon authors the option of
providing a list of versions for various parts of the ABI against which
to check the addon at load time.

Re: nodejs/TSC#651

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[nodejs-github-bot]

@gabrielschulhof build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/2269/pipeline

[gabrielschulhof]

CI: https://ci.nodejs.org/job/node-test-pull-request/20188/

[mcollina]

what's the semversiness of this change? I think it should be semver-major.

[addaleax]

@mcollina I’m not quite sure about the use cases here/if it is worth the added complexity (because it most likely only changes later-occurring errors into earlier ones), but it seems semver-minor as it is an opt-in feature for addons?

[refack]

but it seems semver-minor as it is an opt-in feature for addons?

The addition of the macro seems semver-minor to me as well. But is it possible that the refactoring of node.h has semver-major impact?

[gabrielschulhof]

@refack #include <node.h> after this change will define exactly the same things as now, plus the NODE_MODULE_ABI_* macros and the NODE_MODULE_DECLARE_ABI macro. Unless copying of the node.h header into your own project is part of our semver covenant, this is semver-minor.

[gabrielschulhof]

I'm thinking that, for NODE_ABI_ENGINE_VERSION we may want to structure the number as a bit field to accommodate both engine type (V8/Chakra) and engine version. Or should we split it into two variables?

[refack]

Unless copying of the node.h header into your own project is part of our semver covenant, this is semver-minor.

I agree. Considering that, does this change have a benefit before the next major version bump? If not maybe it's worth waiting just to be extra cautious? If it does, consider my comments non-blocking.

[gabrielschulhof]

@refack so far in node_api.h we've pretty much been copying large-ish parts of node.h because node.h is C++ and node_api.h is C:

• https://github.com/nodejs/node/pull/25539/files#diff-50f0ab3fe6127f546fbe8aabab5a0d7cR17
• https://github.com/nodejs/node/pull/25539/files#diff-50f0ab3fe6127f546fbe8aabab5a0d7cR40
• https://github.com/nodejs/node/pull/25539/files#diff-50f0ab3fe6127f546fbe8aabab5a0d7cR64

If we don't start factoring the C++-agnostic things out of node.h the overlap between the macros in node.h and node_api.h will get even larger. For example, the NODE_MODULE_ABI_*_VERSION have to be in a C++-agnostic header, otherwise they'd need to be copied into node_api.h with NAPI_MODULE_ABI_*_VERSION.

Having said this, we might simply wait until the next major version to land this feature. I mean, it'd make sense that the next major version of Node.js now has the new, cool Addon ABI Declarations™ feature.

[fhinkel]

I'm cleaning out a few old PRs 🧹. I'm closing this due to inactivity. Please re-open if needed!