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feat(erm): implement block-scoped disposal semantics for using declarations#5252

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mrhapile:feat/erm-using-block-semantics
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feat(erm): implement block-scoped disposal semantics for using declarations#5252
mrhapile wants to merge 1 commit intoboa-dev:mainfrom
mrhapile:feat/erm-using-block-semantics

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@mrhapile mrhapile commented Mar 24, 2026

Summary

This PR introduces initial support for Explicit Resource Management (ERM) in Boa by implementing synchronous using declarations with correct block-scoped disposal semantics.

It transitions ERM from a parsed-but-ignored feature to an executable runtime feature aligned with the ECMAScript proposal (partial implementation).

What’s implemented

1. Runtime scaffolding

  • Added core structures:
    • DisposableResource
    • DisposableResourceStack
    • DisposableResourceHint
    • dispose_resources helper
  • Integrated resource tracking into CallFrame

2. Bytecompiler integration

  • Implemented support for:
    • LexicalDeclaration::Using
    • LexicalDeclaration::AwaitUsing (partial)
  • Emits new opcodes:
    • AddDisposableResource
    • AddAsyncDisposableResource

3. VM execution support

  • Added runtime handling for ERM opcodes:
    • Extracts and validates Symbol.dispose
    • Tracks resources per lexical scope
  • Resources are pushed into the current active scope

4. Block-scoped disposal (core feature)

  • Replaced function-level disposal with lexical scope-based disposal
  • Each scope maintains its own DisposableResourceStack
  • Disposal occurs on scope exit (PopEnvironment)
  • Ensures:
    • correct LIFO order
    • proper nested scope handling

5. Scope analysis fixes (critical)

  • Prevented optimizer from eliminating scopes containing using
  • Introduced has_using_declarations tracking
  • Extended support to:
    • block scopes
    • for loops
    • eval environments

6. Abrupt completion handling

  • Fixed disposal during:
    • return
    • throw
    • yield
    • error propagation
  • Ensures remaining scopes are safely disposed without double-disposal

7. Test262 integration

Enabled synchronous using test suite:

Total: 78
Passed: 57
Failed: 21
Ignored: 0

~73% conformance for using semantics.

8. Code quality

  • Resolved all Clippy warnings (CI clean with -D warnings)
  • Removed duplicated match arms and improved pattern matching
  • Preserved future-facing APIs using #[allow(dead_code)]
  • Formatted with cargo fmt

Full Test262 Results

Total tests: 52963
Passed: 50662
Failed: 1155
Ignored: 1146
Conformance: 95.66%

No regressions observed.

Known limitations

The following are intentionally left for follow-up work:

  • ❌ SuppressedError aggregation
  • ❌ Async disposal (await using)
  • ❌ DisposableStack / AsyncDisposableStack builtins
  • ❌ Full error propagation during disposal

Notes

  • Focus of this PR is correct synchronous semantics and runtime integration
  • Establishes a solid foundation for completing ERM support in future PRs

Conclusion

This PR moves ERM in Boa from:

"parsed but ignored"

to:

"executed with correct block-scoped semantics"

and significantly improves Test262 coverage without introducing regressions.

@mrhapile
feat(erm): implement block-scoped disposal for using declarations
28e219c 
Add initial runtime support for Explicit Resource Management (ERM):

- Introduce DisposableResource, DisposableResourceStack, and disposal helpers
- Integrate  and  into bytecompiler
- Add VM opcodes for tracking disposable resources
- Implement block-scoped disposal via lexical environments (PopEnvironment)
- Ensure correct LIFO disposal across nested scopes
- Fix scope analyzer to preserve scopes containing
- Handle abrupt completion (return/throw/yield) without double-disposal
- Enable Test262  tests (57/78 passing)
- Remove all compiler warnings and ensure clean build

Limitations:
- SuppressedError aggregation not implemented
- Async disposal () not fully supported
- DisposableStack builtins not implemented

No regressions in overall Test262 suite.

Signed-off-by: mrhapile <allinonegaming3456@gmail.com>
@github-actions github-actions bot added Waiting On Review Waiting on reviews from the maintainers C-Tests Issues and PRs related to the tests. C-VM Issues and PRs related to the Boa Virtual Machine. C-AST Issue surrounding the abstract syntax tree and removed Waiting On Review Waiting on reviews from the maintainers labels Mar 24, 2026
@github-actions github-actions bot added this to the v1.0.0 milestone Mar 24, 2026
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mrhapile commented Mar 24, 2026

@jedel1043 I’ll continue working on this.......
planning to implement SuppressedError, async disposal (await using), and the remaining builtins like DisposableStack.

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github-actions bot commented Mar 24, 2026

Test262 conformance changes

Test result main count PR count difference
Total 52,963 52,963 0
Passed 50,732 50,840 +108
Ignored 1,426 1,146 -280
Failed 805 977 +172
Panics 0 0 0
Conformance 95.79% 95.99% +0.20%
Fixed tests (108): 
test/built-ins/Symbol/dispose/no-key.js (previously Ignored)
test/built-ins/Symbol/dispose/cross-realm.js (previously Ignored)
test/built-ins/Symbol/dispose/prop-desc.js (previously Ignored)
test/built-ins/Symbol/asyncDispose/no-key.js (previously Ignored)
test/built-ins/Symbol/asyncDispose/cross-realm.js (previously Ignored)
test/built-ins/Symbol/asyncDispose/prop-desc.js (previously Ignored)
test/language/statements/for-of/head-await-using-bound-names-in-stmt.js (previously Ignored)
test/language/statements/for-of/head-using-bound-names-let.js (previously Ignored)
test/language/statements/for-of/head-await-using-bound-names-let.js (previously Ignored)
test/language/statements/for-of/head-using-init.js (previously Ignored)
test/language/statements/for-of/head-await-using-init.js (previously Ignored)
test/language/statements/for-of/head-using-bound-names-in-stmt.js (previously Ignored)
test/language/statements/using/block-local-closure-get-before-initialization.js (previously Ignored)
test/language/statements/using/puts-initializer-on-top-of-disposableresourcestack-subsequent-usings.js (previously Ignored)
test/language/statements/using/using-allows-null-initializer.js (previously Ignored)
test/language/statements/using/redeclaration-error-from-within-strict-mode-function-using.js (previously Ignored)
test/language/statements/using/static-init-await-binding-invalid.js (previously Ignored)
test/language/statements/using/fn-name-cover.js (previously Ignored)
test/language/statements/using/initializer-disposed-at-end-of-block.js (previously Ignored)
test/language/statements/using/fn-name-fn.js (previously Ignored)
test/language/statements/using/global-use-before-initialization-in-prior-statement.js (previously Ignored)
test/language/statements/using/fn-name-gen.js (previously Ignored)
test/language/statements/using/Symbol.dispose-getter.js (previously Ignored)
test/language/statements/using/block-local-use-before-initialization-in-declaration-statement.js (previously Ignored)
test/language/statements/using/throws-if-initializer-missing-Symbol.dispose.js (previously Ignored)
test/language/statements/using/function-local-closure-get-before-initialization.js (previously Ignored)
test/language/statements/using/global-use-before-initialization-in-declaration-statement.js (previously Ignored)
test/language/statements/using/puts-initializer-on-top-of-disposableresourcestack-multiple-bindings.js (previously Ignored)
test/language/statements/using/fn-name-class.js (previously Ignored)
test/language/statements/using/cptn-value.js (previously Ignored)
test/language/statements/using/initializer-disposed-at-end-of-functionbody.js (previously Ignored)
test/language/statements/using/throws-if-initializer-not-object.js (previously Ignored)
test/language/statements/using/Symbol.dispose-method-called-with-correct-this.js (previously Ignored)
test/language/statements/using/using-allows-undefined-initializer.js (previously Ignored)
test/language/statements/using/static-init-await-binding-valid.js (previously Ignored)
test/language/statements/using/fn-name-arrow.js (previously Ignored)
test/language/statements/using/global-closure-get-before-initialization.js (previously Ignored)
test/language/statements/using/function-local-use-before-initialization-in-prior-statement.js (previously Ignored)
test/language/statements/using/throws-if-initializer-Symbol.dispose-property-not-callable.js (previously Ignored)
test/language/statements/using/multiple-resources-disposed-in-reverse-order.js (previously Ignored)
test/language/statements/using/block-local-use-before-initialization-in-prior-statement.js (previously Ignored)
test/language/statements/using/function-local-use-before-initialization-in-declaration-statement.js (previously Ignored)
test/language/statements/using/throws-if-initializer-Symbol.dispose-property-is-undefined.js (previously Ignored)
test/language/statements/using/throws-if-initializer-Symbol.dispose-property-is-null.js (previously Ignored)
test/language/statements/using/gets-initializer-Symbol.dispose-property-once.js (previously Ignored)
test/language/statements/using/syntax/using.js (previously Ignored)
test/language/statements/using/syntax/with-initializer-label-statement.js (previously Ignored)
test/language/statements/using/syntax/using-invalid-objectbindingpattern-after-bindingidentifier.js (previously Ignored)
test/language/statements/using/syntax/using-allows-bindingidentifier.js (previously Ignored)
test/language/statements/using/syntax/using-invalid-for-in.js (previously Ignored)
test/language/statements/using/syntax/with-initializer-if-expression-statement-else-statement.js (previously Ignored)
test/language/statements/using/syntax/with-initializer-while-expression-statement.js (previously Ignored)
test/language/statements/using/syntax/without-initializer-if-expression-statement-else-statement.js (previously Ignored)
test/language/statements/using/syntax/block-scope-syntax-using-declarations-mixed-with-without-initializer.js (previously Ignored)
test/language/statements/using/syntax/using-allows-multiple-bindings.js (previously Ignored)
test/language/statements/using/syntax/using-invalid-arraybindingpattern-after-bindingidentifier.js (previously Ignored)
test/language/statements/using/syntax/without-initializer-while-expression-statement.js (previously Ignored)
test/language/statements/using/syntax/with-initializer-do-statement-while-expression.js (previously Ignored)
test/language/statements/using/syntax/with-initializer-for-statement.js (previously Ignored)
test/language/statements/using/syntax/block-scope-syntax-using-declarations-without-initializer.js (previously Ignored)
test/language/statements/using/syntax/using-invalid-arraybindingpattern.js (previously Ignored)
test/language/statements/using/syntax/with-initializer-if-expression-statement.js (previously Ignored)
test/language/statements/using/syntax/using-invalid-objectbindingpattern.js (previously Ignored)
test/language/statements/using/syntax/using-allowed-at-top-level-of-module.js (previously Ignored)
test/language/statements/using/syntax/without-initializer-do-statement-while-expression.js (previously Ignored)
test/language/statements/using/syntax/without-initializer-label-statement.js (previously Ignored)
test/language/statements/using/syntax/block-scope-syntax-using-declarations-mixed-without-with-initializer.js (previously Ignored)
test/language/statements/using/syntax/without-initializer-for-statement.js (previously Ignored)
test/language/statements/using/syntax/without-initializer-if-expression-statement.js (previously Ignored)
test/language/statements/for-await-of/head-using-init.js (previously Ignored)
test/language/statements/for-await-of/head-await-using-init.js (previously Ignored)
test/language/statements/await-using/global-use-before-initialization-in-prior-statement.js (previously Ignored)
test/language/statements/await-using/await-using-allows-undefined-initializer.js (previously Ignored)
test/language/statements/await-using/redeclaration-error-from-within-strict-mode-function-await-using.js (previously Ignored)
test/language/statements/await-using/function-local-use-before-initialization-in-prior-statement.js (previously Ignored)
test/language/statements/await-using/block-local-use-before-initialization-in-prior-statement.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-switchstatement-defaultclause.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-not-allowed-at-top-level-of-eval.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-objectbindingpattern-after-bindingidentifier.js (previously Ignored)
test/language/statements/await-using/syntax/with-initializer-label-statement.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-not-allowed-at-top-level-of-script.js (previously Ignored)
test/language/statements/await-using/syntax/with-initializer-if-expression-statement-else-statement.js (previously Ignored)
test/language/statements/await-using/syntax/with-initializer-while-expression-statement.js (previously Ignored)
test/language/statements/await-using/syntax/without-initializer-if-expression-statement-else-statement.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-objectbindingpattern.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-arraybindingpattern.js (previously Ignored)
test/language/statements/await-using/syntax/without-initializer-while-expression-statement.js (previously Ignored)
test/language/statements/await-using/syntax/with-initializer-do-statement-while-expression.js (previously Ignored)
test/language/statements/await-using/syntax/with-initializer-for-statement.js (previously Ignored)
test/language/statements/await-using/syntax/block-scope-syntax-await-using-declarations-without-initializer.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-switchstatement-caseclause.js (previously Ignored)
test/language/statements/await-using/syntax/with-initializer-if-expression-statement.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-for-in.js (previously Ignored)
test/language/statements/await-using/syntax/without-initializer-do-statement-while-expression.js (previously Ignored)
test/language/statements/await-using/syntax/without-initializer-label-statement.js (previously Ignored)
test/language/statements/await-using/syntax/without-initializer-for-statement.js (previously Ignored)
test/language/statements/await-using/syntax/block-scope-syntax-await-using-declarations-mixed-with-without-initializer.js (previously Ignored)
test/language/statements/await-using/syntax/await-using-invalid-arraybindingpattern-after-bindingidentifier.js (previously Ignored)
test/language/statements/await-using/syntax/without-initializer-if-expression-statement.js (previously Ignored)
test/language/statements/await-using/syntax/block-scope-syntax-await-using-declarations-mixed-without-with-initializer.js (previously Ignored)
test/staging/explicit-resource-management/async-disposable-stack-adopt-on-disposed-stack.js (previously Ignored)
test/staging/explicit-resource-management/async-disposable-stack-disposed-getter.js (previously Ignored)
test/staging/explicit-resource-management/async-disposable-stack-move-on-disposed-stack.js (previously Ignored)
test/staging/explicit-resource-management/using-with-null-or-undefined.js (previously Ignored)
test/staging/explicit-resource-management/async-disposable-stack-defer-on-disposed-stack.js (previously Ignored)
test/staging/explicit-resource-management/async-disposable-stack-use-on-disposed-stack.js (previously Ignored)
test/staging/explicit-resource-management/Symbol/dispose/cross-realm.js (previously Ignored)
test/staging/explicit-resource-management/Symbol/dispose/prop-desc.js (previously Ignored)

Tested main commit: 8fcbfcbb8b9e70fe878d28376a6496eaa57a70d7
Tested PR commit: 28e219c5b3ab630878f35447b1b06624b3a0d713
Compare commits: 8fcbfcb...28e219c

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codecov bot commented Mar 24, 2026

Codecov Report

❌ Patch coverage is 29.45736% with 91 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.55%. Comparing base (6ddc2b4) to head (28e219c).
⚠️ Report is 918 commits behind head on main.

Files with missing lines Patch % Lines
core/engine/src/vm/opcode/environment/erm.rs 0.00% 47 Missing ⚠️
core/ast/src/scope_analyzer.rs 45.45% 18 Missing ⚠️
core/engine/src/resource_management.rs 28.57% 15 Missing ⚠️
core/engine/src/bytecompiler/mod.rs 0.00% 6 Missing ⚠️
core/engine/src/vm/code_block.rs 0.00% 2 Missing ⚠️
core/engine/src/vm/mod.rs 66.66% 2 Missing ⚠️
core/engine/src/vm/flowgraph/mod.rs 0.00% 1 Missing ⚠️
Additional details and impacted files 
@@             Coverage Diff             @@
##             main    #5252       +/-   ##
===========================================
+ Coverage   47.24%   59.55%   +12.30%     
===========================================
  Files         476      591      +115     
  Lines       46892    63527    +16635     
===========================================
+ Hits        22154    37831    +15677     
- Misses      24738    25696      +958

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  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
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jedel1043 commented Mar 24, 2026

Duplicate of #5079

@jedel1043 jedel1043 marked this as a duplicate of #5079 Mar 24, 2026
@jedel1043 jedel1043 closed this Mar 24, 2026
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