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x/tools/gopls: semanticTokensProvider response uses nulls incorrectly #59479

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mvdan opened this issue Apr 7, 2023 · 6 comments
Closed

x/tools/gopls: semanticTokensProvider response uses nulls incorrectly #59479

mvdan opened this issue Apr 7, 2023 · 6 comments
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@pjweinb
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FrozenDueToAge gopls Issues related to the Go language server, gopls. Tools This label describes issues relating to any tools in the x/tools repository.
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@mvdan
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mvdan commented Apr 7, 2023

What did you do?

Trying a new editor, https://helix-editor.com/, which has built-in support for LSPs like gopls.

I'm using gopls master, just like I usually do with neovim.

What did you expect to see?

It should work out of the box, just like it does with neovim's native lsp support. In fact, I had tried a previous release of Helix with a previous version of gopls and they did work together, so this breakage is new.

What did you see instead?

Helix apparently does not connect to gopls properly. I ended up filing a helix bug at helix-editor/helix#6545, although they seem to have spotted a bug in gopls instead.

I am quoting the relevant comment for reference:

The important lines in the log:

2023-04-01T23:23:46.013 helix_lsp::transport [INFO] <- {"jsonrpc":"2.0","result":{"capabilities":{"textDocumentSync":{"openClose":true,"change":2,"save":{}},"completionProvider":{"triggerCharacters":["."]},"hoverProvider":true,"signatureHelpProvider":{"triggerCharacters":["(",","]},"definitionProvider":true,"typeDefinitionProvider":true,"implementationProvider":true,"referencesProvider":true,"documentHighlightProvider":true,"documentSymbolProvider":true,"codeActionProvider":{"codeActionKinds":["quickfix","refactor.extract","refactor.rewrite","source.fixAll","source.organizeImports"]},"codeLensProvider":{},"documentLinkProvider":{},"workspaceSymbolProvider":true,"documentFormattingProvider":true,"renameProvider":{"prepareProvider":true},"foldingRangeProvider":true,"selectionRangeProvider":true,"executeCommandProvider":{"commands":["gopls.add_dependency","gopls.add_import","gopls.apply_fix","gopls.check_upgrades","gopls.edit_go_directive","gopls.fetch_vulncheck_result","gopls.gc_details","gopls.generate","gopls.go_get_package","gopls.list_imports","gopls.list_known_packages","gopls.mem_stats","gopls.regenerate_cgo","gopls.remove_dependency","gopls.reset_go_mod_diagnostics","gopls.run_govulncheck","gopls.run_tests","gopls.start_debugging","gopls.test","gopls.tidy","gopls.toggle_gc_details","gopls.update_go_sum","gopls.upgrade_dependency","gopls.vendor"]},"callHierarchyProvider":true,"semanticTokensProvider":{"legend":{"tokenTypes":null,"tokenModifiers":null},"range":true,"full":true},"inlayHintProvider":{},"workspace":{"workspaceFolders":{"supported":true,"changeNotifications":"workspace/didChangeWorkspaceFolders"}}},"serverInfo":{"name":"gopls","version":"{\"GoVersion\":\"devel go1.21-bb44c2b54e Fri Mar 31 20:01:17 2023 +0000\",\"Path\":\"golang.org/x/tools/gopls\",\"Main\":{\"Path\":\"golang.org/x/tools/gopls\",\"Version\":\"v0.0.0-20230331191349-65208701901c\",\"Sum\":\"h1:fWtx3BldeTdC8pjqg6KVSfzSW7sDtaRiCZ3B1y/PZk8=\",\"Replace\":null},\"Deps\":[{\"Path\":\"github.com/BurntSushi/toml\",\"Version\":\"v1.2.1\",\"Sum\":\"h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak=\",\"Replace\":null},{\"Path\":\"github.com/google/go-cmp\",\"Version\":\"v0.5.9\",\"Sum\":\"h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=\",\"Replace\":null},{\"Path\":\"github.com/sergi/go-diff\",\"Version\":\"v1.1.0\",\"Sum\":\"h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=\",\"Replace\":null},{\"Path\":\"golang.org/x/exp\",\"Version\":\"v0.0.0-20220722155223-a9213eeb770e\",\"Sum\":\"h1:+WEEuIdZHnUeJJmEUjyYC2gfUMj69yZXw17EnHg/otA=\",\"Replace\":null},{\"Path\":\"golang.org/x/exp/typeparams\",\"Version\":\"v0.0.0-20221212164502-fae10dda9338\",\"Sum\":\"h1:2O2DON6y3XMJiQRAS1UWU+54aec2uopH3x7MAiqGW6Y=\",\"Replace\":null},{\"Path\":\"golang.org/x/mod\",\"Version\":\"v0.9.0\",\"Sum\":\"h1:KENHtAZL2y3NLMYZeHY9DW8HW8V+kQyJsY/V9JlKvCs=\",\"Replace\":null},{\"Path\":\"golang.org/x/sync\",\"Version\":\"v0.1.0\",\"Sum\":\"h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=\",\"Replace\":null},{\"Path\":\"golang.org/x/sys\",\"Version\":\"v0.6.0\",\"Sum\":\"h1:MVltZSvRTcU2ljQOhs94SXPftV6DCNnZViHeQps87pQ=\",\"Replace\":null},{\"Path\":\"golang.org/x/text\",\"Version\":\"v0.8.0\",\"Sum\":\"h1:57P1ETyNKtuIjB4SRd15iJxuhj8Gc416Y78H3qgMh68=\",\"Replace\":null},{\"Path\":\"golang.org/x/tools\",\"Version\":\"v0.7.1-0.20230331191349-65208701901c\",\"Sum\":\"h1:KRo5CL18+P9McX3TfKZwKggqIwa4ACpt7LYLoeOla00=\",\"Replace\":null},{\"Path\":\"golang.org/x/vuln\",\"Version\":\"v0.0.0-20230110180137-6ad3e3d07815\",\"Sum\":\"h1:A9kONVi4+AnuOr1dopsibH6hLi1Huy54cbeJxnq4vmU=\",\"Replace\":null},{\"Path\":\"honnef.co/go/tools\",\"Version\":\"v0.4.2\",\"Sum\":\"h1:6qXr+R5w+ktL5UkwEbPp+fEvfyoMPche6GkOpGHZcLc=\",\"Replace\":null},{\"Path\":\"mvdan.cc/gofumpt\",\"Version\":\"v0.4.0\",\"Sum\":\"h1:JVf4NN1mIpHogBj7ABpgOyZc65/UUOkKQFkoURsz4MM=\",\"Replace\":null},{\"Path\":\"mvdan.cc/xurls/v2\",\"Version\":\"v2.4.0\",\"Sum\":\"h1:tzxjVAj+wSBmDcF6zBB7/myTy3gX9xvi8Tyr28AuQgc=\",\"Replace\":null}],\"Settings\":[{\"Key\":\"-buildmode\",\"Value\":\"exe\"},{\"Key\":\"-compiler\",\"Value\":\"gc\"},{\"Key\":\"-ldflags\",\"Value\":\"-w -s\"},{\"Key\":\"CGO_ENABLED\",\"Value\":\"1\"},{\"Key\":\"CGO_CFLAGS\",\"Value\":\"\"},{\"Key\":\"CGO_CPPFLAGS\",\"Value\":\"\"},{\"Key\":\"CGO_CXXFLAGS\",\"Value\":\"\"},{\"Key\":\"CGO_LDFLAGS\",\"Value\":\"\"},{\"Key\":\"GOARCH\",\"Value\":\"amd64\"},{\"Key\":\"GOOS\",\"Value\":\"linux\"},{\"Key\":\"GOAMD64\",\"Value\":\"v3\"}],\"Version\":\"master\"}"}},"id":0}
2023-04-01T23:23:46.014 helix_lsp [ERROR] failed to initialize language server: failed to parse: data did not match any variant of untagged enum SemanticTokensServerCapabilities

This is an upstream issue with gopls: it's sending

{
  "semanticTokensProvider": {
    "legend": {"tokenTypes": null, "tokenModifiers": null},
    "range": true,
    "full": true
  }
}

in the server capabilities in response to the initialize request.

The nulls are invalid according to the spec: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#semanticTokensLegend. tokenTypes and tokenModifiers are non-nullable. Instead gopls should use an empty list.

Build info

golang.org/x/tools/gopls master
    golang.org/x/tools/gopls@v0.0.0-20230406191632-45ef82945d2c h1:aYohqGdfnEEd5B90Zxl+KfrOo/u+8GrnGkPq5Vn27EQ=
    github.com/BurntSushi/toml@v1.2.1 h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak=
    github.com/google/go-cmp@v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
    github.com/sergi/go-diff@v1.1.0 h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=
    golang.org/x/exp@v0.0.0-20220722155223-a9213eeb770e h1:+WEEuIdZHnUeJJmEUjyYC2gfUMj69yZXw17EnHg/otA=
    golang.org/x/exp/typeparams@v0.0.0-20221212164502-fae10dda9338 h1:2O2DON6y3XMJiQRAS1UWU+54aec2uopH3x7MAiqGW6Y=
    golang.org/x/mod@v0.10.0 h1:lFO9qtOdlre5W1jxS3r/4szv2/6iXxScdzjoBMXNhYk=
    golang.org/x/sync@v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
    golang.org/x/sys@v0.7.0 h1:3jlCCIQZPdOYu1h8BkNvLz8Kgwtae2cagcG/VamtZRU=
    golang.org/x/text@v0.9.0 h1:2sjJmO8cDvYveuX97RDLsxlyUxLl+GHoLxBiRdHllBE=
    golang.org/x/tools@v0.8.1-0.20230406191632-45ef82945d2c h1:6FcxpuzgR8bx6R5nFoULRCVtztRxhuBSTH3e5ZGcaec=
    golang.org/x/vuln@v0.0.0-20230110180137-6ad3e3d07815 h1:A9kONVi4+AnuOr1dopsibH6hLi1Huy54cbeJxnq4vmU=
    honnef.co/go/tools@v0.4.2 h1:6qXr+R5w+ktL5UkwEbPp+fEvfyoMPche6GkOpGHZcLc=
    mvdan.cc/gofumpt@v0.4.0 h1:JVf4NN1mIpHogBj7ABpgOyZc65/UUOkKQFkoURsz4MM=
    mvdan.cc/xurls/v2@v2.4.0 h1:tzxjVAj+wSBmDcF6zBB7/myTy3gX9xvi8Tyr28AuQgc=
go: devel go1.21-9be533a8ee Fri Apr 7 10:09:11 2023 +0000
@gopherbot gopherbot added Tools This label describes issues relating to any tools in the x/tools repository. gopls Issues related to the Go language server, gopls. labels Apr 7, 2023
@gopherbot gopherbot added this to the Unreleased milestone Apr 7, 2023
@mvdan mvdan mentioned this issue Apr 7, 2023
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@pjweinb
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pjweinb commented Apr 7, 2023

Thanks for the bug report. I'll try to fix it. (I presume the client in SemanticTokensClientCapabilities is not sending any tokenTypes.)

@mvdan
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mvdan commented Apr 7, 2023

Out of curiosity, are there any checks that the JSON encoded by gopls adheres to the LSP spec, perhaps if they publish a JSONSchema? Presumably that sort of check or static analysis could have caught this bug, and there might be other similar bugs lurking. I only found this one because Helix's decoder for LSP types appears to be fairly strict, whereas Neovim's appears to be more forgiving.

@pjweinb
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pjweinb commented Apr 7, 2023 via email

@mvdan
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mvdan commented Apr 7, 2023

Interesting, thanks for the context. You might like to hear that with @dsnet and others we've been looking at a new encoding/json design, and it no longer encodes nil slices as null: https://pkg.go.dev/github.com/go-json-experiment/json#readme-behavior-changes

So that would at least solve this one quirk.

With optional fields, could you not use pointers and omitempty?

With union/sum types, I agree that that's simply a limitation of the Go type system. You could potentially still do something involving interfaces and unexported methods, like go/ast does, though that would add a bit more boilerplate.

@gopherbot
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Change https://go.dev/cl/483216 mentions this issue: gopls: strict LSP compliance for empty slices

@mvdan
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mvdan commented Apr 11, 2023

Confirming that the integration with Helix is fixed :)

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