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hasMutableExportedBinding skips destructured declarations, so a live exported binding still gets settled #74
Description
Reading through the sealCjsExports work from #73, I think hasMutableExportedBinding misses destructured declarations, which lets exactly the case it guards against through.
src/compile.ts:148:
function hasMutableExportedBinding(source: ts.SourceFile): boolean {
const mutableLocals = new Set<string>();
for (const statement of source.statements) {
if (!ts.isVariableStatement(statement)) continue;
const isConst = (statement.declarationList.flags & ts.NodeFlags.Const) !== 0;
if (isConst) continue;
const exported = ts.getModifiers(statement)?.some(m => m.kind === ts.SyntaxKind.ExportKeyword);
for (const declaration of statement.declarationList.declarations) {
if (!ts.isIdentifier(declaration.name)) continue; // <-- binding patterns skipped
if (exported) return true;
mutableLocals.add(declaration.name.text);
}
}
...
}The isIdentifier check sits before both branches, so any binding pattern is dropped early. That misses two shapes:
export let { counter } = obj; // never returns truelet { counter } = obj; // counter never lands in mutableLocals,
export { counter }; // so the named-export scan below misses it tooEither way hasMutableExportedBinding returns false, settling stays enabled, and the accessor gets snapshotted. That produces the divergence the comment right above the function describes: require(pkg).counter keeps reporting the load-time value while import { counter } reports the current one.
const destructuring is correctly irrelevant here — it's filtered by the isConst check above. The gap is only for let/var binding patterns.
Treating a non-const declaration with a binding pattern as mutable would close the first shape; collecting the destructured element names into mutableLocals would close the second.
I have not built a package to reproduce this end to end — it's a read of the code as merged, and the same lines are on main now (src/compile.ts:156). If destructured exports are outside what zshy intends to support, this is not worth your time.
To be upfront about where this came from: I found it with a code review tool I am building (ReviewGate) while running it over real repositories, then read the function and checked each shape against it by hand before writing this up. Close it if I have misread the intent.
Activity
pullfrog commentedon Sep 8, 2026