TaintFlow not picking up on implicit toString()

[edkazcarlson-ms]

Hello,
When the this keyword is used in an interpolated string with no property identifiers/ methods, C# treats the this keyword to implicitly be this.toString(). In testing, doing $"{this}" and $"{this.toString()}" result in the same string, however CodeQL only seems to be detecting the taint flow with the version with .toString() (see attached file). Can a future release of CodeQL please fix this so that we can properly track taint flows when they pass through fields that are used in the toString() method? Thank you.
Attached zip

[michaelnebel]

Thank you for reporting this.
I can confirm that this is a general problem for all implicit ToString calls (and not only related to string interpolation and this).
We have opened an internal issue for tracking this.

[edkazcarlson-ms]

Thank you for the quick update! Should I leave this ticket open for tracking purposes or just close it if there's a different internal one already.

[michaelnebel]

I think we can close this issue.

[michaelnebel]

Fix for binary (string concatenation) and string interpolation expressions was fixed here: #18446