private static string Ctor(char c, int count) { if (count <= 0) { if (count == 0) { return(Empty); } throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_NegativeCount); } string result = FastAllocateString(count); if (c != '\0') { SpanHelpers.Fill(ref result._firstChar, (uint)count, c); } return(result); }