Add (unstable) documentation for `--env` command line option · rust-lang/rust@dc2f77a (original) (raw)

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	1	+# `env`
	2	+
	3	+The tracking issue for this feature is: [#118372](https://github.com/rust-lang/rust/issues/118372).
	4	+
	5	+------------------------
	6	+
	7	+This option flag allows to specify environment variables value at compile time to be
	8	+used by `env!` and `option_env!` macros.
	9	+
	10	+When retrieving an environment variable value, the one specified by `--env` will take
	11	+precedence. For example, if you want have `PATH=a` in your environment and pass:
	12	+
	13	+```bash
	14	+rustc --env PATH=env
	15	+```
	16	+
	17	+Then you will have:
	18	+
	19	+```rust,no_run
	20	+assert_eq!(env!("PATH"), "env");
	21	+```
	22	+
	23	+Please note that on Windows, environment variables are case insensitive but case
	24	+preserving whereas `rustc`'s environment variables are case sensitive. For example,
	25	+having `Path` in your environment (case insensitive) is different than using
	26	+`rustc --env Path=...` (case sensitive).