rustup show fails with panic on Windows

[sprowell]

See also (closed) issue #1357 (which I cannot seem to re-open). This is the latest rustup (downloaded 7/1/2018). I get a panic with rustup show on Windows 10 after successful install of rust.

>rustup show
Default host: i686-pc-windows-msvc

installed toolchains
--------------------

thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', src\libcore\option.rs:335:20
note: Run with `RUST_BACKTRACE=1` for a backtrace.

Other commands work.

>rustup update
info: syncing channel updates for 'stable-i686-pc-windows-msvc'
info: syncing channel updates for 'nightly-i686-pc-windows-msvc'
info: checking for self-updates

   stable-i686-pc-windows-msvc unchanged - rustc 1.27.0 (3eda71b00 2018-06-19)
  nightly-i686-pc-windows-msvc unchanged - rustc 1.28.0-nightly (e3bf634e0 2018-06-28)

Have repeated and confirmed that the problems seems to be the lack of a default toolchain.

[Diggsey]

Interesting, it should not be easy to get in a situation where there is no default toolchain. What steps did you take to get to that point? Also what is the contents of your ~/.rustup/settings.toml file?

[JustAPerson]

I'm hitting this and #1436. I tried using rustup-init.exe which got stuck at the installing component 'rust-docs'. Both rustup update and rustup toolchain install get stuck there.

~/.rustup/settings.toml:

default_host_triple = "x86_64-pc-windows-msvc"
telemetry = false
version = "12"

[overrides]

[dten]

rustup default stable-x86_64-pc-windows-msvc fixed it for me

[mati865]

Rustup doesn't get stuck at installing component 'rust-docs' but it takes a lot time because of NTFS #1540.

[johnthagen]

which got stuck at the installing component 'rust-docs'

Rustup doesn't get stuck at installing component 'rust-docs' but it takes a lot time because of NTFS

I reported added a progress bar to component installs to help solve this very case (#1557)

[colindean]

I hit this just now after installing rustup via scoop. My settings.toml is the same as the previous comment's. When I run rustup default stable-x86_64-pc-windows-msvc, I get:

> rustup default stable-x86_64-pc-windows-msvc
?[1minfo: ?[0musing existing install for 'stable-x86_64-pc-windows-msvc'
?[1minfo: ?[0mdefault toolchain set to 'stable-x86_64-pc-windows-msvc'

  ?[1mstable-x86_64-pc-windows-msvc unchanged?[0m - rustc 1.32.0 (9fda7c223 2019-01-16)

This is after a little bit of thrashing, doing rustup install stable and rustup install 1.32.0 and having both do something even though I would think that stable would resolve to 1.32.0 right now.

It seems to work now, for reasons I don't comprehend. I'm able to cargo build.

[rbtcollins]

So I think this should be broken into two problems:

• sometimes we don't get a default toolchain
• when there isn't a default toolchain, rustup show errors - which was cleanly filed as rustup show errors on empty toolchain #1450

I propose that we reopen 1450, fix that because its clear and simple, fix it (with the case that no default results in a link to this ticket), and then try to figure out the sporadic failure to have a default here)

[kinnison]

We've not panic!()d on a lack of default toolchain for a few releases now, instead you get a well-formed error: no default toolchain configured though perhaps we could then offer a hint on how to fix that.

Regarding why there's no default toolchain, I'm not sure, so we can proceed with investigating that on this issue.

[kinnison]

I'm not sure that this has been reproduced in the past 6 months. Does anyone have any way to reproduce this which they've not shared yet?