Test.CoreLib is missing DefaultMemberAttribute #107953
Description
Description
Reproduction Steps
N/A
Expected behavior
DefaultMemberAttribute is defined in the core library
Actual behavior
DefaultMemberAttribute is not defined in the core library
Regression?
No response
Known Workarounds
No response
Configuration
No response
Other information
Compiler team might decide to report an error for an indexer declaration when the attribute is missing. This will cause a build break of the library after upgrade if the attribute is missing.