feat: implement import.defer() and import.source() dynamic import syntax#5035
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jedel1043 merged 4 commits intoboa-dev:mainfrom Mar 15, 2026
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Test262 conformance changes
Fixed tests (135):Tested main commit: |
Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #5035 +/- ##
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+ Coverage 47.24% 59.11% +11.86%
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Files 476 563 +87
Lines 46892 62665 +15773
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+ Hits 22154 37042 +14888
- Misses 24738 25623 +885 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Add parsing and runtime support for import.defer(specifier) and import.source(specifier) dynamic import syntax. Changes: - Add ImportPhase enum (Evaluation, Defer, Source) to boa_ast - Extend parser to detect and parse import.defer() and import.source() - Thread phase through bytecode compiler as IndexOperand - Update VM ImportCall handler to decode phase operand - Source phase: reject with SyntaxError per GetModuleSource() spec - Defer phase: proceed with standard evaluation semantics - Remove source-phase-imports from ignored features Note: import-defer remains in the ignored features list since full deferred evaluation semantics (deferred namespace objects, evaluation triggers) are not yet implemented.
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Address review feedback: - Add 'defer' and 'source' to static_syms! for compile-time Sym constants - Simplify is_keyword_call to only detect keyword( patterns - Add separate is_import_phase_call helper using Sym::DEFER/Sym::SOURCE - Restructure let-else chain into distinct branches for import( vs import.defer(/import.source(
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Yep, looks great! Thank you!
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This Pull Request adds parsing and runtime support for
import.defer()andimport.source()dynamic import syntax, enabling 64 previously-ignored test262 tests.It changes the following:
ImportPhaseenum (Evaluation,Defer,Source) and aphasefield to theImportCallAST node incore/ast/src/expression/call.rs, with properToInternedStringoutput for each phase.core/parser/src/parser/expression/left_hand_side/mod.rsto detect and parseimport.defer(expr)andimport.source(expr)syntax, including 4-token lookahead inis_keyword_calland phase-aware token consumption.core/engine/src/bytecompiler/expression/mod.rsto encodeImportPhaseas anIndexOperand(0=evaluation, 1=defer, 2=source) on theImportCallinstruction.phase: IndexOperandto theImportCallopcode definition incore/engine/src/vm/opcode/mod.rsand updated the code block display incore/engine/src/vm/code_block.rsto show phase names.ImportCallhandler incore/engine/src/vm/opcode/call/mod.rsto decode the phase operand: source phase rejects withSyntaxErrorperGetModuleSource()spec (16.2.1.7.2), defer phase uses standard evaluation semantics.import-deferandsource-phase-importsfrom the ignored features list intest262_config.toml, bringingdynamic-import/catchsuite from 112/176 to 176/176 (100% conformance).