net: expose context Canceled/DeadlineExceeded error

[pascaldekloe]

Issue #28529 could be solved with the new error wrapping now.

What did you do?

Check for context.Canceled with errors.Is seems reasonable.

https://play.golang.org/p/-JTEZXGyfQ6

$ go version
go version go1.13.5 darwin/amd64

[dmitshur]

Thanks for making this issue.

Can you elaborate on what problem it would help solve to expose this information? What is it that cannot be done (or can be done, but inconveniently) before this is resolved, and how will it be done after?

/cc @mikioh @bradfitz @ianlancetaylor

Also /cc @bcmills who commented on the relevant issue #28529.

[pascaldekloe]

Generally speaking you want to continue the abort (by returning context.Canceled) if the context expired. Dial errors on the other hand must be reported [logged]. Maybe a retry or two?