Document the use of toolchain link

[jonhoo]

The current output of toolchain --help mentions that "rustup can also install toolchains from [..] local builds", but then does not go into further detail. toolchain link is the command meant for that purpose, but its --help output is, well, unhelpful:

$ rustup toolchain link --help
rustup-toolchain-link
Create a custom toolchain by symlinking to a directory

USAGE:
    rustup toolchain link <toolchain> <path>

FLAGS:
    -h, --help    Prints help information

ARGS:
    <toolchain>
    <path>

In particular, it should at the very least be noted that path should be /path/to/rust/build/$triple/stage1, and link should be pointed to from toolchain --help. It'd also be useful to mention that only a rustc build is required, not a full cargo build.

[brson]

Thank you for the bug report @jonhoo !

[typesanitizer]

PR submitted here: #1017

[durka]

Would be great to also add some error checking, so if you try to rustup toolchain link stage1/bin or stage1/bin/rustc instead of totally mysterious "infinite recursion detected" later.

[typesanitizer]

1. @durka, what are all the things that need to be checked before linking? In my build, I have a lot of .so files inside stage1/lib and .rlib and .so files in stage1/lib/x86_64-unknown-linux-gnu/lib.
2. I'm not sure which function should handle the error checking though: toolchain_link calls install_from_dir which calls install which calls run which basically calls utils::symlink_dir. Which function's responsibility would it be to handle this error? I suppose we could do it in toolchain_link itself by just calling rustup_utils::utils::assert_is_file for $path/bin/rustc.

[durka]

At least a sanity check that bin, lib, and bin/rustc are in the expected place would be nice.

…

On Sat, Apr 1, 2017 at 12:04 AM, theindigamer ***@***.***> wrote: 1. @durka <https://github.com/durka>, what are all the things that need to be checked before linking? In my build, I have a lot of .so files inside stage1/lib and .rlib and .so files in stage1/lib/x86_64-unknown-linux-gnu/lib. 2. I'm not sure which function should handle the error checking though: toolchain_link calls install_from_dir which calls install which calls run basically calls utils::symlink_dir. Which function's responsibility would it be to handle this error? I suppose we could do it in toolchain_link itself by just calling rustup_utils::utils::assert_ is_file for $path/bin/rustc. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#954 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAC3n8gVDX-pmZrGXWVvXfFQ2lcEtr9dks5rrcy9gaJpZM4L-rWz> .

[brson]

Looks like the original issue is fixed. Thanks @theindigamer. Do we need to open another issue for the followups mentioned here cc @durka @theindigamer ?

[typesanitizer]

@brson the merged PR included error checking for directories as suggested by @durka . Is there anything else that requires a follow up?

[brson]

Nope! Thanks @theindigamer.