Golang x/tools/go/ast/inspector: panics on Node slice of 32M entries

#!stacks
"gopanic" && "golang.org/x/tools/go/ast/inspector.(*visitor).push:+24"

Issue created by stacks.

func (v *visitor) push(ek edge.Kind, eindex int, node ast.Node) {
    ...
    // 32M elements in an []ast.Node ought to be enough for anyone!
    if ek2, eindex2 := unpackEdgeKindAndIndex(packEdgeKindAndIndex(ek, eindex)); ek2 != ek || eindex2 != eindex {
        panic("Node slice index exceeded uint25")
    }
}

This stack dYd0DQ was reported by telemetry:

• crash/crash
• runtime.gopanic:+69,+0x167
• golang.org/x/tools/go/ast/inspector.(*visitor).push:+24,+0x22f
• golang.org/x/tools/go/ast/inspector.walk:+1,+0x39
• golang.org/x/tools/go/ast/inspector.walkList[...]:=21,+0x2b44
• golang.org/x/tools/go/ast/inspector.walk:+49,+0x2b14
• golang.org/x/tools/go/ast/inspector.walkList[...]:=21,+0x1d8d
• golang.org/x/tools/go/ast/inspector.walk:+260,+0x1d65
• golang.org/x/tools/go/ast/inspector.walkList[...]:=21,+0x3fee
• golang.org/x/tools/go/ast/inspector.walk:+285,+0x3c1
• golang.org/x/tools/go/ast/inspector.walkList[...]:=21,+0x2cb4
• golang.org/x/tools/go/ast/inspector.walk:+305,+0xcd4
• golang.org/x/tools/go/ast/inspector.traverse:+18,+0x13d
• golang.org/x/tools/go/ast/inspector.New:=74,+0x4e6
• golang.org/x/tools/gopls/internal/cache/parsego.Parse:+75,+0x4ca
• golang.org/x/tools/gopls/internal/cache.(*parseCache).startParse.func1:+5,+0xf5
• golang.org/x/tools/internal/memoize.(*Promise).run.func2.1:+7,+0x95
• runtime/trace.WithRegion:+19,+0xd0
• golang.org/x/tools/internal/memoize.(*Promise).run.func2:+1,+0x11c
• runtime.goexit:+0,+0x0

golang.org/x/tools/gopls@v0.19.1 go1.24.4 windows/amd64 other,vscode-insiders (6)

Comment From: adonovan

The crash is trivial to reproduce by loading the output of this program into gopls:

    fmt.Println(`package p; var _ = []int{`)
    fmt.Println(strings.Repeat("0,", 1<<25))
    fmt.Println(`}`)

Not sure how to fix it, nor whether fixing it should be a priority. Fixing the code generator would be a better solution.

Comment From: gabyhelp

Related Issues

• x/tools/gopls: slice OOB panic in fixAST on array type #70745 (closed)
• x/tools/gopls: xrefs.Index panics after "can't fail" pgf.PosRange #70446 (closed)
• x/tools/gopls: Parse: crash in fixInitStmt #72026 (closed)
• x/tools/gopls: sigpanic in persistent.(*mapNode).forEach (bad SP) #71115
• x/tools/gopls: Inline: panic in falcon analysis (unexpected core type) #74393 (closed)
• x/tools/gopls: panic in aeshashbody on behalf of mapaccess2_faststr: string memory corrupted #71367
• x/tools/gopls: OOM reported by fatal in runtime.mallocgc (windows) #70445 (closed)
• x/tools/gopls: analysisinternal.ZeroValue crash on (presumably) unsafe.Pointer #70585 (closed)
• x/tools/gopls: slice bounds out of range - internal/lsp/cache.fixArrayType #58943 (closed)
• x/tools/gopls: illegal line number panic #37226 (closed)

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