go/src/cmd/compile/internal/types2/errsupport.go

// lookupError returns a case-specific error when a lookup of selector sel in the
// given type fails but an object with alternative spelling (case folding) is found.
// If structLit is set, the error message is specifically for struct literal fields.
func (check *Checker) lookupError(typ Type, sel string, obj Object, structLit bool) string { … }

// tail returns the string s without its first (UTF-8) character.
// If len(s) == 0, the result is s.
func tail(s string) string { … }