Description

string.Contains returns unexpected results when called on an empty string on iOS. This is the code in question:

"".Contains("ö", StringComparison.CurrentCultureIgnoreCase);

Results:

.net 8:

.net 9:

Project to reproduce the issue:
https://github.com/markuspalme/dotnetruntime-contains

Reproduction Steps

To reproduce the issue, call string.Containson an empty string and run the code on net9-ios:

"".Contains("ö", StringComparison.CurrentCultureIgnoreCase);

Expected behavior

The result should be false, an empty string does certainly not contain a character.

Actual behavior

On .net 9 the call returns true.

Regression?

This is a regression, the same code returns false on .net 8.

Known Workarounds

No response

Configuration

.net SDK 9.0.100 running on iOS 18.1 ARM64.

Other information

No response