commonjs export binding not updated in ForInOrOfStatement

TypeScript Version: 3.7.2

Search Terms: commonjs export for of

Code

// @module: commonjs
// @target: esnext
let foo = '';
export { foo };
for (foo in {}) { }
for (foo of []) {}
for ({foo} of [{foo}]) {}

Expected behavior:

for...in and for...of should update the export binding.

for (_a in {}) { 
  exports.foo = foo = _a;
}
for (_b of []) {
  exports.foo = foo = _b;
}
for (_c of [{foo}]) {
  exports.foo = foo = _c.foo;
}

Actual behavior:

Binding is not updated

Playground Link: https://www.typescriptlang.org/play/?target=99&module=1#code/DYUwLgBAZg9jEF4IHJkG4BQIAeAHGATpAN7RwQC+msBEAFLPAJYB2ExFAlO5RjfYwgwoEANoBdbhz6F6xRhSEjR8uBUnsKQA

Start by reproducing the issue with the provided TypeScript code using CommonJS and ESNext settings, then inspect the emitted JavaScript for each for-in and for-of form. Trace the compiler's handling of export bindings in these loop forms and verify that the generated output updates exports.foo as shown.