fix(compiler): cannot chain ?? expressions

[Chriscbr]

Fixes #1875

This fixes the issue by updating the precedent rules so the operation is right-associative. For now, expressions like a ?? b or a ?? b ?? c still have to return a non-optional value (like Rust's unwrap_or), but we can consider making it more flexible / open in the way that C# or Swift allows if appropriate in the future.

Checklist

• Title matches Winglang's style guide
• Description explains motivation and solution
• Tests added (always)
• Docs updated (only required for features)
• Added pr/e2e-full label if this feature requires end-to-end testing

By submitting this pull request, I confirm that my contribution is made under the terms of the Wing Cloud Contribution License.

[github-actions]

Thanks for opening this pull request! 🎉
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Topic	Owner
Wing SDK and utility APIs	@chriscbr
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Platforms and plugins	@hasanaburayyan
Frontend resources (website, react, etc)	@tsuf239
Language design	@eladb
VSCode extension and language server	@markmcculloh
Compiler architecture, inflights, lifting	@yoav-steinberg
Wing Testing Framework	@tsuf239
Wing CLI	@markmcculloh
Build system, dev environment, releases	@markmcculloh
Library Ecosystem	@chriscbr
Documentation	@hasanaburayyan
SDK test suite	@tsuf239
Examples	@hasanaburayyan
Wing Playground	@eladcon

[monadabot]

Console preview environment is available at https://wing-console-pr-5987.fly.dev 🚀

Last Updated (UTC) 2024-03-18 21:31

[monadabot]

Benchmarks

Comparison to Baseline ⬜⬜🟥⬜⬜⬜🟥⬜⬜⬜⬜⬜⬜

Benchmark	Before	After	Change
version	61ms±2.42	59ms±0.72	-2ms (-3.07%)⬜
empty.test.w -t sim	485ms±4.63	488ms±2.99	+3ms (+0.61%)⬜
empty.test.w -t tf-aws	700ms±4.89	723ms±9.3	+23ms (+3.27%)🟥
hello_world.test.w -t sim	511ms±5.02	523ms±6.44	+12ms (+2.4%)⬜
hello_world.test.w -t tf-aws	1640ms±10.04	1656ms±7.39	+16ms (+0.98%)⬜
functions_10.test.w -t sim	589ms±8.14	603ms±8.83	+14ms (+2.41%)⬜
functions_10.test.w -t tf-aws	2210ms±10.37	2259ms±18.63	+49ms (+2.2%)🟥
jsii_small.test.w -t sim	499ms±4.92	496ms±3.04	-3ms (-0.61%)⬜
jsii_small.test.w -t tf-aws	717ms±3.19	720ms±6.26	+4ms (+0.5%)⬜
jsii_big.test.w -t sim	2926ms±28.35	2931ms±8.68	+5ms (+0.16%)⬜
jsii_big.test.w -t tf-aws	3182ms±12.8	3179ms±24.36	-3ms (-0.09%)⬜
functions_1.test.w -t sim	528ms±5.76	535ms±7.27	+7ms (+1.3%)⬜
functions_1.test.w -t tf-aws	965ms±6.49	960ms±11.12	-4ms (-0.43%)⬜

⬜ Within 1.5 standard deviations
🟩 Faster, Above 1.5 standard deviations
🟥 Slower, Above 1.5 standard deviations

Benchmarks may vary outside of normal expectations, especially when running in GitHub Actions CI.

Results

name	mean	min	max	moe	sd
version	59ms	58ms	61ms	1ms	1ms
empty.test.w -t sim	488ms	480ms	495ms	3ms	4ms
empty.test.w -t tf-aws	723ms	703ms	743ms	9ms	13ms
hello_world.test.w -t sim	523ms	509ms	539ms	6ms	9ms
hello_world.test.w -t tf-aws	1656ms	1639ms	1670ms	7ms	10ms
functions_10.test.w -t sim	603ms	586ms	618ms	9ms	12ms
functions_10.test.w -t tf-aws	2259ms	2237ms	2327ms	19ms	26ms
jsii_small.test.w -t sim	496ms	488ms	503ms	3ms	4ms
jsii_small.test.w -t tf-aws	720ms	707ms	737ms	6ms	9ms
jsii_big.test.w -t sim	2931ms	2917ms	2956ms	9ms	12ms
jsii_big.test.w -t tf-aws	3179ms	3128ms	3215ms	24ms	34ms
functions_1.test.w -t sim	535ms	518ms	552ms	7ms	10ms
functions_1.test.w -t tf-aws	960ms	933ms	986ms	11ms	16ms

Last Updated (UTC) 2024-03-18 21:37

[yoav-steinberg]

👍

[mergify]

Thanks for contributing, @Chriscbr! This PR will now be added to the merge queue, or immediately merged if rybickic/unwrap-or2 is up-to-date with main and the queue is empty.

[monadabot]

Congrats! 🚀 This was released in Wing 0.61.17.