/// <summary>
/// What we need to do is find a *repeatable* arbitrary way to choose between
/// two errors; we can for example simply take the one that is lower in alphabetical
/// order when converted to a string. As an optimization, we compare error codes
/// first and skip string comparison if they differ.
/// </summary>
private static int CanonicallyCompareDiagnostics(Diagnostic x, Diagnostic y)
{
ErrorCode xCode = (ErrorCode)x.Code;
ErrorCode yCode = (ErrorCode)y.Code;
int codeCompare = xCode.CompareTo(yCode);
// ToString fails for a diagnostic with an error code that does not prevernt successful delegate conversion.
// Also, the order doesn't matter, since all such diagnostics will be dropped.
if (!ErrorFacts.PreventsSuccessfulDelegateConversion(xCode) || !ErrorFacts.PreventsSuccessfulDelegateConversion(yCode))
{
return(codeCompare);
}
// Optimization: don't bother
return(codeCompare == 0 ? string.CompareOrdinal(x.ToString(), y.ToString()) : codeCompare);
}