Golang x/tools/gopls: nil deref in DidCreateFiles on result of call to completion.NewFile

#!stacks
"sigpanic" && "server.(*server).DidCreateFiles:+20"

Issue created by stacks.

// NewFile returns a document change to complete an empty go file.
func NewFile(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) (*protocol.DocumentChange, error) {
    if bs, err := fh.Content(); err != nil || len(bs) != 0 {
        return nil, err <----------- may return no result and no error
    }
    meta, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI())
    if err != nil {
        return nil, err
    }

@xieyuschen

This stack WhZjCw was reported by telemetry:

• crash/crash
• runtime.gopanic:+69,+0x153
• runtime.panicmem:=262,+0x2ff
• runtime.sigpanic:+19,+0x2cc
• golang.org/x/tools/gopls/internal/server.(*server).DidCreateFiles:+20,+0x1b0
• golang.org/x/tools/gopls/internal/protocol.serverDispatch:+650,+0x2d87
• golang.org/x/tools/gopls/internal/lsprpc.(*streamServer).ServeStream.ServerHandler.func4:+5,+0x73
• golang.org/x/tools/gopls/internal/lsprpc.(*streamServer).ServeStream.handshaker.func5:+52,+0x68f
• golang.org/x/tools/gopls/internal/protocol.Handlers.MustReplyHandler.func1:+2,+0xbf
• golang.org/x/tools/gopls/internal/protocol.Handlers.AsyncHandler.func2.2:+3,+0x8f
• runtime.goexit:+0,+0x3

golang.org/x/tools/gopls@v0.19.0-pre.2 go1.24.3 darwin/arm64 vscode (2)
golang.org/x/tools/gopls@v0.19.0-pre.1 go1.24.3 darwin/arm64 other (9)
golang.org/x/tools/gopls@v0.19.0-pre.2 go1.24.3 darwin/arm64 other (1)

Dups: 6JFvKA

Comment From: adonovan

Let's cherrypick a fix for this into rc3.

Comment From: adonovan

This stack 6JFvKA was reported by telemetry:

• crash/crash
• runtime.gopanic:+69,+0x167
• runtime.panicmem:=262,+0x358
• runtime.sigpanic:+19,+0x328
• golang.org/x/tools/gopls/internal/server.(*server).DidCreateFiles:+20,+0x215
• golang.org/x/tools/gopls/internal/protocol.serverDispatch:+650,+0x36db
• golang.org/x/tools/gopls/internal/lsprpc.(*streamServer).ServeStream.ServerHandler.func4:+5,+0x84
• golang.org/x/tools/gopls/internal/lsprpc.(*streamServer).ServeStream.handshaker.func5:+52,+0x908
• golang.org/x/tools/gopls/internal/protocol.Handlers.MustReplyHandler.func1:+2,+0xc5
• golang.org/x/tools/gopls/internal/protocol.Handlers.AsyncHandler.func2.2:+3,+0x95
• runtime.goexit:+0,+0x0

golang.org/x/tools/gopls@v0.19.0-pre.2 go1.24.3 linux/amd64 vscode (1)
golang.org/x/tools/gopls@v0.19.0-pre.2 go1.24.3 darwin/amd64 vscode-insiders (1)
golang.org/x/tools/gopls@v0.19.0-pre.1 go1.24.3 linux/amd64 vscode (1)

Comment From: gabyhelp

Related Issues

• x/tools/gopls: Completion: nil deref in expectedCompositeLiteralType #72136 (closed)
• x/tools/gopls: nil Signature (?) deref in Completion #70634 (closed)
• x/tools/gopls: nil deref in Snapshot.MetadataForFile #73114
• x/tools/gopls: nil deref panic in go.test code action #72907 (closed)
• x/tools/gopls: nil deref in 'go vendor' Snapshot.GoCommandInvocation #73891
• x/tools/gopls: nil deref in x/telemetry/internal/counter.(*Counter).add #73890
• x/tools/gopls: Hover: nil deref in parseDocLink #70635 (closed)
• x/tools/gopls: Completion: nil deref panic in addFieldItems #72828 (closed)
• x/tools/gopls: OOB index crash in completion.expectedReturnStmtType #70636 (closed)
• x/tools/gopls: Package.Path called on nil Package in AddTestForFunc #73687 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

Comment From: gopherbot

Change https://go.dev/cl/680259 mentions this issue: gopls/internal/golang/completion: return error if file is not new