Incorrect name ambiguity with discard lambda parameters

[TessenR]

Version Used:

commit 18305a1f4b82de5092cc8f90573afa5a6d091cf8
Merge: afe689ab1a9 265022a3e73
Author: Manish Vasani <mavasani@microsoft.com>
Date:   Fri Apr 29 09:21:23 2022 -0700

    Merge pull request #60906 from mavasani/FixAllCodeRefactoring_2

    Add FixAll support for code refactorings (approach #2)

Steps to Reproduce:

Compile the following code with preview language version.

class AAttribute : System.Attribute
{
  public AAttribute(string s) { }
}

class C
{
  void M(int _)
  {
    System.Func<string, string, int> a = [A(nameof(_))](_, _) => _;
  }
}

Expected Behavior:
The code compiles. nameof(_) references the parameter int _ since lambda parameters are discards and not actual elements.
Note that _ in the lambda body correctly binds to int _ and doesn't consider discard elements

Actual Behavior:
Incorrect and strangely worded error is reported:
error CS0229: Ambiguity between 'string' and 'string'

Notes:
Note that this is also a breaking change as the same code compiles with C# 10. It's a small one and in line with other breaking changes caused by parameter scope changes, but given that here it doesn't bring any new functionality it seems avoidable.

[jcouv]

Good catch. Fixed in 17.3