[JSC] Top-level function declarations should be lexical in module code #19207
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Thank you Ross! Much appreciated 🙇 |
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https://bugs.webkit.org/show_bug.cgi?id=263269 <rdar://problem/117086061> Reviewed by Ross Kirsling. The spec has at least 8 occurrences of > It is a Syntax Error if the LexicallyDeclaredNames of X contains any duplicate entries. early error rules that preclude duplicate lexical declarations. For backwards-compatibility, LexicallyDeclaredNames [1] skips top-level function declarations inside `ScriptBody : StatementList` by invoking TopLevelLexicallyDeclaredNames [2], which returns an empty list for them [3]. However, the semantics of LexicallyDeclaredNames is entirely different for `ModuleItem` (also please see note WebKit#1). The fact that top-level function declarations are lexical in module code is also evident during binding initialization [4]. This change makes top-level function declarations in module code behave like `let` rather than `var`, introducing early errors that come with it, like disallowing duplicates with `var` and `function`. Since inside declareFunction() we can't rely neither on `m_scriptMode` (which is always `Module`, even for nested functions that absolutely should not throw SyntaxError for duplicate declarations), nor on `m_parseMode` (it's already the parse mode of the declared function itself), this change introduces isModuleCode() [5], refactoring parse mode handling in Scope. Also, this patch aligns declareFunctionAsLet() with declareVariable(), called for `let` declarations, by adding `m_declaredVariables` check, which may fail only in module code. Removes now incorrect (for module code only) ASSERT that isn't particularly useful given how simple declareFunction() now is. Aligns JSC with V8 and SpiderMonkey. [1]: https://tc39.es/ecma262/#sec-static-semantics-lexicallydeclarednames [2]: https://tc39.es/ecma262/#sec-static-semantics-toplevellexicallydeclarednames [3]: https://tc39.es/ecma262/#prod-HoistableDeclaration [4]: https://tc39.es/ecma262/#sec-source-text-module-record-initialize-environment (step 24.iii) [5]: https://tc39.es/ecma262/#sec-types-of-source-code * JSTests/modules/async-function-export.js: Moved to JSTests/stress/modules-syntax-error.js. * JSTests/stress/modules-syntax-error.js: * JSTests/test262/expectations.yaml: Mark 8 tests as passing. * Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp: (JSC::BytecodeGenerator::BytecodeGenerator): * Source/JavaScriptCore/parser/Parser.cpp: (JSC::Parser<LexerType>::Parser): (JSC::Parser<LexerType>::parseFunctionInfo): (JSC::Parser<LexerType>::parseMemberExpression): * Source/JavaScriptCore/parser/Parser.h: (JSC::Scope::setSourceParseMode): (JSC::Scope::isGlobalCode const): (JSC::Scope::isModuleCode const): (JSC::Scope::declareFunctionAsLet): (JSC::Scope::setIsGlobalCode): (JSC::Scope::setIsModuleCode): (JSC::Parser::declareFunction): (JSC::Scope::setIsGlobalCodeScope): Deleted. (JSC::Scope::isGlobalCodeScope const): Deleted. Canonical link: https://commits.webkit.org/269485@main
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Committed 269485@main (2838f14): https://commits.webkit.org/269485@main Reviewed commits have been landed. Closing PR #19207 and removing active labels. |
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