Non-strict-mode-compliant codegen for entry with the name arguments containing mixed exports

[yyx990803]

Rollup Version

2.78.0

Operating System (or Browser)

any

Node Version (if applicable)

any

Link To Reproduction

https://rollupjs.org/repl/?version=2.78.0&shareable=JTdCJTIybW9kdWxlcyUyMiUzQSU1QiU3QiUyMm5hbWUlMjIlM0ElMjJtYWluLmpzJTIyJTJDJTIyY29kZSUyMiUzQSUyMmV4cG9ydCUyMGRlZmF1bHQlMjAlN0IlN0QlMjIlMkMlMjJpc0VudHJ5JTIyJTNBdHJ1ZSU3RCUyQyU3QiUyMm5hbWUlMjIlM0ElMjJhcmd1bWVudHMuanMlMjIlMkMlMjJjb2RlJTIyJTNBJTIyZXhwb3J0JTIwY29uc3QlMjBmb28lMjAlM0QlMjAxJTVDbmV4cG9ydCUyMGRlZmF1bHQlMjAlN0IlN0QlMjIlMkMlMjJpc0VudHJ5JTIyJTNBdHJ1ZSU3RCU1RCUyQyUyMm9wdGlvbnMlMjIlM0ElN0IlMjJmb3JtYXQlMjIlM0ElMjJlcyUyMiUyQyUyMm5hbWUlMjIlM0ElMjJteUJ1bmRsZSUyMiUyQyUyMmFtZCUyMiUzQSU3QiUyMmlkJTIyJTNBJTIyJTIyJTdEJTJDJTIyZ2xvYmFscyUyMiUzQSU3QiU3RCU3RCUyQyUyMmV4YW1wbGUlMjIlM0FudWxsJTdE

Expected Behaviour

The generated code should be valid in strict mode (i.e. modules)

Actual Behaviour

When an entry file contains both named and default exports:

export const foo = 1
export default {}

Rollup rewrites them into a single export statement:

const foo = 1;
var arguments = {};

export { arguments as default, foo };

The default export value is assigned to a variable, which uses the file's name as its variable name. The variable name gets prefixed with _ for most keywords, but somehow arguments is missed, which is in fact invalid in strict mode / module context.

Actually, I don't see a reason why the temp variable needs to use the filename, maybe just use something like _default with conflict postfixes is simpler and safer.

[lukastaegert]

Thanks for spotting, fix at #4613.

but somehow arguments is missed

turns out arguments is not a reserved word, which is what we were looking for, but it is a variable name with special logic attached to it...

Actually, I don't see a reason why the temp variable needs to use the filename, maybe just use something like _default with conflict postfixes is simpler and safer.

There are other situations where those names are helpful and it avoids having a dozen _default with attached numbers in the generated code where it is not clear where they came from.