x/tools/gopls: empty hover response should be null, not a zero struct

[zikaeroh]

Please answer these questions before submitting your issue. Thanks!

What did you do?

Hovered over a keyword, like package or func.

What did you expect to see?

No hover, as it's not really helpful.

What did you see instead?

No hover, but my client (VS Code) reports that the markup content kind is unsupported.

The logs for the hover above say:

Trace - 10:30:51.946 AM] Sending request 'textDocument/hover - (5)'.
Params: {"textDocument":{"uri":"file:///home/jake/zikaeroh/hortbot/hortbot/internal/bot/repeat.go"},"position":{"line":0,"character":3}}


[Trace - 10:30:51.949 AM] Received response 'textDocument/hover - (5)' in 3ms.
Result: {"contents":{"kind":"","value":""},"range":{"start":{"line":0,"character":0},"end":{"line":0,"character":0}}}

So gopls is sending a zero'd hover response rather than nil/null. There might be other conditions where a zero hover is returned, but hovering over a keyword is the easiest method to reproduce this.

Build info

golang.org/x/tools/gopls master
    golang.org/x/tools/gopls@v0.1.8-0.20200228194328-a628ca32ebc0 h1:/+Nv8+K3X0WFGQqkDtuQYvf1VoDYtKkFw6hBGjwyunk=
    github.com/BurntSushi/toml@v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
    github.com/sergi/go-diff@v1.0.0 h1:Kpca3qRNrduNnOQeazBd0ysaKrUJiIuISHxogkT9RPQ=
    golang.org/x/mod@v0.1.1-0.20191105210325-c90efee705ee h1:WG0RUwxtNT4qqaXX3DPA8zHFNm/D9xaBpxzHt1WcA/E=
    golang.org/x/sync@v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
    golang.org/x/tools@v0.0.0-20200228194328-a628ca32ebc0 h1:bC/KxYpsTCppyXiguiVppCnZLkQpMNIi042/S5bYanA=
    golang.org/x/xerrors@v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbOeHJjicWYPqR9bpxqxYG2pA=
    honnef.co/go/tools@v0.0.1-2020.1.3 h1:sXmLre5bzIR6ypkjXCDI3jHPssRhc8KD/Ome589sc3U=
    mvdan.cc/xurls/v2@v2.1.0 h1:KaMb5GLhlcSX+e+qhbRJODnUUBvlw01jt4yrjFIHAuA=

Go info

go version go1.14 linux/amd64

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/jake/.cache/go-build"
GOENV="/home/jake/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/jake/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/jake/zikaeroh/hortbot/hortbot/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build561120271=/tmp/go-build -gno-record-gcc-switches"

[gopherbot]

Thank you for filing a gopls issue! Please take a look at the Troubleshooting guide, and make sure that you have provided all of the relevant information here.

[zikaeroh]

Aha, so this only happens when I've set -remote=auto. Many hovers appear to do this, especially when the file has syntax errors and you're hovering over them.

cc @findleyr

[findleyr]

Thanks for the report!

Just so I understand: is the problem just the hover serialization, or are you also not getting hover results when you'd expect them?

[zikaeroh]

I believe it's only under cases where gopls would have been sending a nil hover. Other hovers are fine. It just seems like nil hovers are being converted to empty on forward.

[findleyr]

Thanks, that seems like a perfectly plausible bug -- I'll look into it.

[gopherbot]

Change https://golang.org/cl/222058 mentions this issue: internal/lsp/protocol: unmarshal to pointers when dispatching requests