String IndexOf method return different results on mac an windows

[fujihara]

IndexOf method of string class is returning different results on macOs and Windows.

This issue started after .NET Core release update.

var str = "The quick brown fox jumps over the lazy dog\r\n";
if (str.IndexOf("\n") >= 0) {
    Console.WriteLine("OK");
}
else {
    Console.WriteLine("BAD");
}

On Windows machine it always print:
OK

On Mac it prints:
BAD

I fixed my code passing a char to IndexOf instead string:
if (str.IndexOf('\n') >= 0)

But would be better if both platform to work consistently.

Thanks

PS: I had posted this issue on core repository (dotnet/core#193)

[ghost]

Related: https://github.com/dotnet/corefx/issues/9202

[stephentoub]

Looks like https://github.com/dotnet/corefx/issues/4587

[danmoseley]

I agree it seems to be dotnet/corefx#4587. Please see explanation there