[matt-edmondson]

Part of #106. JavaScript was the last target the issue's triage listed as still writing keyword-named identifiers verbatim.

What was wrong

The JavaScript generator had no reserved-word set, so a keyword-named parameter, local, function, class or top-level name came out as written. For example, total(in, typeof), function return(with) and let new = ... all fail to parse (SyntaxError: Unexpected token 'in').

Design decision

The last triage comment on #106 left this open: JavaScript accepts a keyword as a member name after a . (holder.default, this.switch()), and as a field, accessor or method name. The shared EscapeReference and SpellCallee, however, escaped every segment. This PR takes the option that renames as little as possible:

• Bindings are escaped with an underscore, at the declaration and at every use: parameters, locals, free functions, classes (including a nested class expression's own name), top-level let/const, and enum and alias constants. extends, new and an alias's value go through EscapeReference too.
• Members keep their names. Fields, accessors, methods, enumeration members and object-literal keys are written as declared, so the object's shape is unchanged.

Changes

• LanguageGeneratorBase: a new protected virtual bool EscapesMemberNames => true. When a target returns false:

  • EscapeReference escapes only a reference's leading segment.
  • A call with a receiver writes its callee verbatim.
  • SpellCallee counts only free functions, because methods weren't escaped.

  Every other generator keeps the default, so their output is unchanged.

• JavaScriptGenerator:

  • Adds ReservedWords: the reserved words, the strict-mode future reserved words, the literals, and arguments/eval, which strict code can't bind. Class bodies and modules are strict.
  • Adds IsReceiverWord (this, super, true, false, null) and EscapesMemberNames => false.
  • Routes every binding site through EscapeIdentifier.

Tests

New file Coder.Test/Languages/JavaScriptReservedWordIdentifierTests.cs. The tests live in their own file so this PR and #445 (Go), which both extend the shared test file, merge in either order. I checked with git merge-tree that this branch merges cleanly with both #445 and #446.

• JavaScript_KeywordNamesRunAndResolve runs the generated script under node with a driver. The driver reads back holder.class, holder.default, a get delete() accessor, total(in_, typeof_) with locals let_/new_, this.switch() called from another method, Flag.null, return_(…) called from relay(), a top-level var_, and class Child extends import_.
• JavaScript_ReferenceEscapesTheBindingButNotTheMember checks the text: this.class, this.switch() and get delete() are unescaped, and there is no this_, class_, switch_ or null_.

With the two generator files reverted, both tests fail: node reports SyntaxError: Unexpected token 'in', and the text assertion fails. With the change, the full suite passes: 1666/1666 on net10.0, Linux.

Left open on #106

From the earlier triage: in C, the function-pointer member (*name) of an interface's vtable struct still isn't escaped.

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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