Fix panic in Function constructor with nested lexical bindings (#4531)

[Deepak-negi11]

Fixes #4531

Problem

Function("function f() { const a = 42; return () => a; } return f()()")() panics with "index out of bounds" / "must be declarative environment".

Root Cause

The Function constructor compiles with force_function_scope=true, but FunctionExpression::analyze_scope was missing the scope index optimization step. The generic optimize_scope_indices also didn't account for the forced function scope, causing compile-time scope indices to mismatch the runtime environment stack.

Fix

Added optimize_scope_indices_function_constructor() in scope_analyzer.rs that calls visit_function_like directly with force_function_scope=true and call it from FunctionExpression::analyze_scope.

Test

Added a regression test function_constructor_nested_lexical_binding.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,862	52,862	0
Passed	49,497	49,497	0
Ignored	2,261	2,261	0
Failed	1,104	1,104	0
Panics	0	0	0
Conformance	93.63%	93.63%	0.00%

[hansl]

@Deepak-negi11 Could you fix the formatting issue? Everything else looks fine, so once that passes I'll approve the merge.

[hansl]

Just cargo fmt should do.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.02%. Comparing base (6ddc2b4) to head (241b9aa).
⚠️ Report is 673 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4645      +/-   ##
==========================================
+ Coverage   47.24%   57.02%   +9.78%     
==========================================
  Files         476      549      +73     
  Lines       46892    60138   +13246     
==========================================
+ Hits        22154    34295   +12141     
- Misses      24738    25843    +1105     

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[jedel1043]

Got late to review this, but I'm wondering how this affects ordinary FunctionExpressions, since this not only touches all Function() calls, but also all (function() {}) style expressions.

[jedel1043]

I guess it would just optimize scope indices two times instead of only one for (function(){}), so I think it would've been better to inline optimize_scope_indices_function_constructor into the specific place where it's used

boa/core/engine/src/builtins/function/mod.rs

Lines 650 to 654 in 957e6f8

	if let Err(reason) =
	function.analyze_scope(strict, context.realm().scope(), context.interner())
	{
	return Err(js_error!(SyntaxError: "failed to analyze function scope: {}", reason));
	}

which avoids affecting all non-dynamic functions.