fix: avoid traversing on Program:enter

[nmn]

Better compatibility with pre-transformation

StyleX is sometimes used alongside other code transformation that can generate StyleX code. Examples include the React-Strict-DOM Babel plugin and tailwind-to-stylex.

The StyleX compiler has to do multiple passes of the entire tree to compile and then optimize the code. Previously, some of the transformations happened using a path.traverse in Program:enter. Because of how Babel runs multiple plugins, this meant that StyleX would often transform before previous transforms were completed. This could result incomplete compilation.

This change moves some code around to move things to the normal tree traversal or Program:exit. This will ensure that StyleX can consume any code generated by previous transforms.

Note

There is no functional change to the output of the Babel plugin.

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.

@stylexjs/[email protected] size:compare
./size-compare.js /tmp/tmp.qPIIp4d3tx /tmp/tmp.HP3qK9rivF

Results	Base	Patch	Ratio
stylex/lib/stylex.js
· compressed	729	729	1.00
· minified	2,541	2,541	1.00
stylex/lib/StyleXSheet.js
· compressed	1,266	1,266	1.00
· minified	3,776	3,776	1.00
rollup-example/.build/bundle.js
· compressed	563,025	563,025	1.00
· minified	10,185,368	10,185,368	1.00
rollup-example/.build/stylex.css
· compressed	99,154	99,154	1.00
· minified	745,649	745,649	1.00

[necolas]

FWIW the RSD preset doesn't generate any StyleX code

[necolas]

Is this something you can unit test to validate?

[nmn]

FWIW the RSD preset doesn't generate any StyleX code

I should explain better, but RSD will transform stylex={} into {...stylex.props()} right? StyleX normally optimizes them away if all the styles are defined locally. When the stylex.props is inserted by a Babel plugin, it may fail to do so.

Is this something you can unit test to validate?

Yes, I don't want to add a new dependency just for a test, so I'll try coming up with a minimal Babel plugin just for the test.

(I tested this independently on top of tailwind-to-stylex.)