`//@ {unset-,}{rustc,exec}-env` parsing is a footgun

[jieyouxu]

Apparently

//@ rustc-env: RUSTC_BOOTSTRAP=1

is not the same as

//@ rustc-env:RUSTC_BOOTSTRAP=1

compiletest will parse the former as an env var called ⌴RUSTC_BOOTSTRAP (incl. the whitespace).

[Shunpoco]

Hi, I'd like to take this ticket, but what is the best solution?

1. Accept such whitespace: I think we will modify Config::parse_env to remove such whitespaces,
2. Fix all test codes which put a whitespace, or
3. Panic when parse_env detects such a whitespace

[jieyouxu]

I haven't quite determined what's the best solution to this yet.

[jieyouxu]

Tagging as E-hard and E-needs-design because it needs to not be a footgun on its own but also it needs to be homogenous with other directive syntaxes.