Add an impl for Box<Error> from String.

[michaelsproul]

Closes #30156.

[rust-highfive]

r? @alexcrichton

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[alexcrichton]

@bors: r+ 577b267

[sfackler]

Implementations aren't checked for stability so this should really be flagged stable.

[michaelsproul]

I was wondering about that. I'll amend the commit and do a push.

[michaelsproul]

@alexcrichton this seems to have stalled (no acknowledgement from @bors), and the r+ needs to be on the new commit. It's holidays though so take it easy! 😄

[netvl]

Is there a reason why there is no similar implementation for &str?

[alexcrichton]

@michaelsproul oh if the commit is updated it needs a new r+

As @netvl says actually, could you add an impl for &str as well?

[michaelsproul]

Will fix it up soon.

[michaelsproul]

Updated! I really like the &str implementation, great idea @netvl.

[alexcrichton]

@bors: r+ c1e527f

cc @rust-lang/libs, just a heads up, seems easy though as we have From<&str> for Box<Error+Send+Sync> so it seems like there's no reason to not also have it for Box<Error>

[bors]

⌛️ Testing commit c1e527f with merge ac9be00...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt

[brson]

bhsausabsha on IRC asked for a backport

[bluss]

backporting would solve this beta regression IIUC #30634

[brson]

Per @nikomatsakis accepted for backport. This fixes another regression.