fix: tree shaking multi decl

[IWANABETHATGUY]

Description

for case:

// index.js
import {a,} from './share'
console.log(a)
// share.js
export const a = 1000, b = 1000;

Before

// share.js
const a = 100, b = 1000;
// main1.js
console.log(a);

After

// share.js
const a = 100;
// main1.js
console.log(a);

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 89.47368% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 87.03%. Comparing base (97d50b5) to head (3529eb1). Report is 1 commits behind head on main.

Files	Patch %	Lines
...down/src/finalizer/impl_visit_mut_for_finalizer.rs	76.19%	5 Missing :warning:
crates/rolldown_common/src/types/stmt_info.rs	85.71%	2 Missing :warning:
...tes/rolldown/src/stages/link_stage/tree_shaking.rs	96.96%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1150      +/-   ##
==========================================
- Coverage   87.04%   87.03%   -0.02%     
==========================================
  Files         122      122              
  Lines        6007     6053      +46     
==========================================
+ Hits         5229     5268      +39     
- Misses        778      785       +7     

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[github-actions[bot]]

Benchmarks Rust

• target: main(73ae76c6171fbe514e605ce20fd07fe28ed76501)
• pr: fix/tree-shaking-multi-decl(3529eb12cebe50df7134414c869eb87aba4e479c)

group                                      pr                                     target
-----                                      --                                     ------
rolldown benchmark/threejs-bundle          1.00     31.1±0.40ms        ? ?/sec    1.00     31.2±0.37ms        ? ?/sec
rolldown benchmark/threejs-scan            1.01     21.8±0.55ms        ? ?/sec    1.00     21.5±0.17ms        ? ?/sec
rolldown benchmark/threejs-sourcemap       1.00     43.1±0.77ms        ? ?/sec    1.02     43.8±0.99ms        ? ?/sec
rolldown benchmark/threejs10x-bundle       1.02    328.2±2.96ms        ? ?/sec    1.00    322.9±2.85ms        ? ?/sec
rolldown benchmark/threejs10x-scan         1.01    211.3±3.65ms        ? ?/sec    1.00    210.0±1.86ms        ? ?/sec
rolldown benchmark/threejs10x-sourcemap    1.01   467.2±11.16ms        ? ?/sec    1.00    463.1±7.90ms        ? ?/sec

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #1150 will not alter performance

_{Comparing fix/tree-shaking-multi-decl (3529eb1) with main (73ae76c)}

Summary

✅ 6 untouched benchmarks

[hyf0]

It's suggested that:

• You could place the transform logic on multiple declarations in https://github.com/rolldown/rolldown/blob/4dc323cf46681d57d56592ee0b7ebdefdaa96268/crates/rolldown/src/utils/tweak_ast_for_scanning.rs
• Create a VariableDeclarationExt trait in https://github.com/rolldown/rolldown/blob/4dc323cf46681d57d56592ee0b7ebdefdaa96268/crates/rolldown_oxc_utils/src/ext/mod.rs
• Create a method fn unfold_declarators(&mut self, alloc: &Allocator) -> Vec<VariableDeclaration> on VariableDeclarationExt. Feel free to choose a more suitable function name or signature.

[IWANABETHATGUY]

This PR is blocked by the source map modification revert,

[IWANABETHATGUY]

closed in favor of #1564