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x/playground: play.golang.org hangs on a simple program with unreachable code #27980

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marat-rkh opened this issue Oct 3, 2018 · 10 comments
Closed

x/playground: play.golang.org hangs on a simple program with unreachable code #27980

marat-rkh opened this issue Oct 3, 2018 · 10 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done.
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Unreleased

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@marat-rkh
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I run this simple program on play.golang.org:

package main

func main() {
	return
	_ = "unreachable"
}

After I press "Run", the output window at the bottom of the page says "Waiting for remote server..." and nothing happens. If I run this program locally, it terminates instantly.
@pjebs
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pjebs commented Oct 3, 2018

I can verify this.

@bradfitz
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bradfitz commented Oct 3, 2018

/cc @andybons @dmitshur @broady

@bradfitz bradfitz changed the title play.golang.org hangs on a simple program with unreachable code x/playground: play.golang.org hangs on a simple program with unreachable code Oct 3, 2018
@gopherbot gopherbot added this to the Unreleased milestone Oct 3, 2018
@dmitshur
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dmitshur commented Oct 5, 2018

It looks like a bug in the frontend script:

image

It seems to happen whenever there's vet output (in this case, a warning about unreachable code) and nothing is written to stdout.

@dmitshur
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dmitshur commented Oct 5, 2018

The failing code is:

if (dataVet.Errors) {
	// inject errors from the vet as the first event in the output
	data.Events.unshift({Message: 'Go vet exited.\n\n', Kind: 'system', Delay: 0});
	data.Events.unshift({Message: dataVet.Errors, Kind: 'stderr', Delay: 0});
}

It fails when data.Events is null rather than an array.

@dmitshur dmitshur added the NeedsFix The path to resolution is known, but the work has not been done. label Oct 5, 2018
@andybons
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andybons commented Oct 5, 2018

@ysmolsky

@ysmolski
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ysmolski commented Oct 5, 2018

I will take a look.

@ysmolski
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ysmolski commented Oct 5, 2018 •
edited

@andybons
I do remember fixing this long time ago. It seems that playground uses old version of godoc:

# Repo golang.org/x/tools at 48418e5 (2018-05-08)
ENV REV=48418e5732e1b1e2a10207c8007a5f959e422f20
RUN go get -d golang.org/x/tools/go/ast/astutil `#and 3 other pkgs` &&\
    (cd /go/src/golang.org/x/tools && (git cat-file -t $REV 2>/dev/null || git fetch -q origin $REV) && git reset --hard $REV)

And this was fixed on May 25th: https://go-review.googlesource.com/c/tools/+/113875

@gopherbot
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Change https://golang.org/cl/140017 mentions this issue: playground: use latest godoc with fixed playground.js

@bradfitz
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bradfitz commented Oct 5, 2018

Reopening until this is deployed.

@bradfitz bradfitz reopened this Oct 5, 2018
@dmitshur
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dmitshur commented Oct 5, 2018

Redeployed play.golang.org, confirmed the issue is resolved:

image

(Source: https://play.golang.org/p/egwBhqHiRnk.)

@dmitshur dmitshur closed this as completed Oct 5, 2018
matfax pushed a commit to gofunky/playground that referenced this issue Oct 8, 2018
@ysmolski @matfax
Dockerfile: use latest x/tools containing the CL 113875
233a2e0 
Use the godoc with the CL 113875. That CL handles the case when there
was no output from the user program and vet returned an error.

Fixes golang/go#27980

Change-Id: I8f3d5ff477fb930c099fd9780c102c8421403e55
Reviewed-on: https://go-review.googlesource.com/c/140017
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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@bradfitz @ysmolski @andybons @dmitshur @pjebs @marat-rkh @gopherbot