x/tools/gopls: SEGV in (*types.*Checker).Ident due to nil or invalid *ast.Ident in syntax tree

[adonovan]

#!stacks
"sigpanic" && "types.(*Checker).ident:+4"

Issue created by stacks.

Similar to #76238, likely more memory corruption.

This stack pNXpPw was reported by telemetry:

• crash/crash
• runtime.throw:+9,+0x47
• runtime.sigpanic:+33,+0x26b
• go/types.(*Checker).ident:+4,+0x7f
• go/types.(*Checker).typInternal:+26,+0x8c4
• go/types.(*Checker).definedType:+1,+0x2e
• go/types.(*Checker).varType:+1,+0x24
• go/types.(*Checker).collectParams:+17,+0x245
• go/types.(*Checker).funcType:+34,+0x1f5
• go/types.(*Checker).funcDecl:+18,+0xd1
• go/types.(*Checker).objDecl:+154,+0xa64
• go/types.(*Checker).ident:+54,+0x364
• go/types.(*Checker).exprInternal:+11,+0x9b7
• go/types.(*Checker).rawExpr:+10,+0x18b
• go/types.(*Checker).genericExpr:+1,+0x3d
• go/types.(*Checker).genericExprList:+77,+0xb6a
• go/types.(*Checker).callExpr:+134,+0x964

golang.org/x/tools/gopls@v0.21.0 go1.25.2 linux/amd64 gopls.client=other,vscode (1)

Use this command to reproduce the executable:
(HOME=$(mktemp -d); GOOS=linux GOARCH=amd64 GOTOOLCHAIN=go1.25.2 go install golang.org/x/tools/gopls@v0.21.0 && find $HOME/go/bin -type f)
To disassemble: go tool objdump exe | less

[gabyhelp]

Related Issues

• x/tools/gopls: SEGV loading m.used field from non-nil map pointer (in types.Scope.elems map) #76979
• x/tools/gopls: impossible panic reading rtype.hash in type assertion #76328
• x/tools/gopls: impossible crash in (*types.Checker).basicLit #76329
• x/tools/gopls: impossible panic in BlockStmt.End (type checking IfStmt with nil Body) #76327
• x/tools/gopls: SEGV in go/types due to invalid pointer in BinaryExpr.Y #76238
• x/tools/gopls: bug in Codec[...].Encode #76978
• x/tools/gopls: nil (or invalid) *ExprStmt pointer in AST #76747
• x/tools/gopls: SEGV accessing g in function prolog (R28 is nil or invalid) #76158
• x/tools/gopls: type checker panics when fed invalid BasicLit.Kind #76953
• x/tools/gopls: objectpath: panic due to nil *types.Signature #75575

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