x/tools/gopls: xrefs.Index panics after "can't fail" pgf.PosRange

[adonovan]

#!stacks
"runtime.gopanic" && "xrefs.Index.func2:+3"

Issue created by stacks.

        nodeRange := func(n ast.Node) protocol.Range {
            rng, err := pgf.PosRange(n.Pos(), n.End())
            if err != nil {
                panic(err) // can't fail                  <-- CAN FAIL
            }
            return rng
        }

This stack LDqHyA was reported by telemetry:

• crash/crash
• runtime.gopanic:+69
• golang.org/x/tools/gopls/internal/cache/xrefs.Index.func2:+3
• golang.org/x/tools/gopls/internal/cache/xrefs.Index.func3:+32
• go/ast.inspector.Visit:+1
• go/ast.Walk:+1
• go/ast.Walk:+58
• go/ast.Walk:+87
• go/ast.Walk:+57
• go/ast.Walk:+87
• go/ast.walkList[...]:=21
• go/ast.Walk:+161
• go/ast.walkList[...]:=21
• go/ast.Walk:+178
• go/ast.Walk:+299
• go/ast.walkList[...]:=21
• go/ast.Walk:+308
• go/ast.Inspect:=372
• golang.org/x/tools/gopls/internal/cache/xrefs.Index:+30
• golang.org/x/tools/gopls/internal/cache.(*syntaxPackage).xrefs.func1:+1
• sync.(*Once).doSlow:+5

  golang.org/x/tools/gopls@v0.17.0-pre.2 go1.23.3 linux/amd64 vscode (1)

[gabyhelp]

Related Issues

• x/tools/gopls: panic after failed PosRange in xrefs.Index #67704
• x/tools/gopls: Highlight: nil deref panic on CompositeLiteral with no type #68918 (closed)
• x/tools/gopls: automated issue report (crash) #48763 (closed)
• x/tools/gopls: crash due to panic: invalid Pos value (go/token/position.go:281) #47231 (closed)
• x/tools/gopls: Hover: panic in lookupObjectByName #69616
• x/tools/gopls: illegal line number panic #37226 (closed)
• x/tools/gopls: panic in token.File.Name within PackageDocHTML (telemetry) #70149 (closed)
• x/tools/gopls: crash in Hover (telemetry) #69362
• x/tools/gopls: automated issue report (crash) #40819 (closed)
• x/tools/gopls: invalid memory address or nil pointer dereference on highlight #68927 (closed)

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[gopherbot]

Change https://go.dev/cl/630675 mentions this issue: gopls/internal/crash: don't crash in xrefs on out of bound nodes