erroneous "set but not used" warnings with reference variables #14801

Environment

• OS and Version: Arch Linux (linux 7.2.6.arch2-1)
• VS Code Version: 1.139.0 commit 2242ebbb54efeeb0129e08e919e7e8d43033cd83
• C/C++ Extension Version: pre-release 1.35.2
• If using SSH remote, specify OS of remote machine: N/A

Bug Summary and Steps to Reproduce

Bug Summary:

In the following code:

void modify(int& x){
    x = 3;
}

x is being erroneously marked as set-but-unused, even though the assignment can be useful.

Steps to reproduce:

1. Create a blank folder and a .cpp file with the content shown above in it
2. Open the file
3. See error

Expected behavior:
The variable is recognized as used and not dimmed, and there is no warning message on hover.

Configuration and Logs

c_cpp_properties.json: (none)

Log Diagnostics output

Language Server logging

Other Extensions

No response

Additional context

No response