String.IndexOf broken for 'ʻ'

[faimada]

var tmp = "aʻ";
Console.WriteLine( tmp.Contains("a") ); // True
Console.WriteLine( tmp.IndexOf("a") ); // -1

[ellismg]

The problem here is Contains does an ordinal comparison, whereas IndexOf does a linguistic comparison. In this case, the second character (U+02BB, MODIFIER LETTER TURNED COMMA) modifies the previous letter such that the pair is treated differently from the raw letter a.

This happens with other characters as well, for example U+0303 (COMBINING TILDE).

If you change your sample to be:

var tmp = "aʻ";
Console.WriteLine(tmp.Contains("a")); // True
Console.WriteLine(tmp.IndexOf("a", StringComparison.Ordinal)); // 0

Then you get the behavior you expect, since now both functions are doing ordinal comparisons.

[stephentoub]

@faimada, I'm going to close this out; please reopen if you still believe there's a problem. Thanks.