x/tools/gopls: CodeActions: "end < start" panic

[adonovan]

#!stacks
"gopanic" && "Cursor.FindByPos" && "goAssembly:+33"

Issue created by stacks.

This stack wpBMRw was reported by telemetry:

• crash/crash
• runtime.gopanic:+69,+0x153
• golang.org/x/tools/go/ast/inspector.Cursor.FindByPos:+2,+0x1e7
• golang.org/x/tools/gopls/internal/golang.goAssembly:+33,+0x2df
• golang.org/x/tools/gopls/internal/golang.CodeActions:+64,+0x51f
• golang.org/x/tools/gopls/internal/server.(*server).CodeAction:+154,+0x3ff
• golang.org/x/tools/gopls/internal/protocol.serverDispatch:+160,+0x1d9f
• 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@v0.19.1 go1.24.4 darwin/arm64 vscode (3)

Dups: JJ6f0Q

[gabyhelp]

Related Issues

• x/tools/gopls: nil deref panic in go.test code action #72907 (closed)
• x/tools/gopls: CodeAction: nil panic in findMatchingDiagnostics #71028 (closed)
• x/tools/gopls: Implementation (by signatures): nil panic in dynamicFuncCallType #74305 (closed)
• x/tools/gopls: nil deref in x/telemetry/internal/counter.(*Counter).add #73890
• x/tools/gopls: Hover: nil deref in golang.StdSymbolOf #70969 (closed)
• x/tools/gopls: analysisinternal.ZeroValue crash on (presumably) unsafe.Pointer #70585 (closed)
• x/tools/gopls: Definition: out-of-bounds panic #73797 (closed)
• x/tools/gopls: Hover: nil deref in parseDocLink #70635 (closed)
• x/tools/gopls: completion: failed type assertion in inferExpectedTypeArg #70889 (closed)
• x/tools/gopls: Hover: invalid nil entry in types.Defs map #69362 (closed)

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

[gopherbot]

Change https://go.dev/cl/684255 mentions this issue: gopls/internal/protocol: Mapper: reject start > end

[adonovan]

This stack JJ6f0Q was reported by telemetry:

• crash/crash
• runtime.gopanic:+69,+0x167
• golang.org/x/tools/go/ast/inspector.Cursor.FindByPos:+2,+0x1d7
• golang.org/x/tools/gopls/internal/golang.goAssembly:+33,+0x2db
• golang.org/x/tools/gopls/internal/golang.CodeActions:+64,+0x624
• golang.org/x/tools/gopls/internal/server.(*server).CodeAction:+154,+0x5a8
• golang.org/x/tools/gopls/internal/protocol.serverDispatch:+160,+0x239c
• 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 go1.24.3 linux/amd64 vscode (3)