[clang] [Concepts] Add Decls from the outer scope of the current lambda for conversion function constraints (PR #83420)

[via cfe-commits]

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@@ -691,11 +691,15 @@ bool Sema::CheckFunctionConstraints(const FunctionDecl *FD,
   // A lambda conversion operator has the same constraints as the call operator
   // and constraints checking relies on whether we are in a lambda call operator
   // (and may refer to its parameters), so check the call operator instead.
+  // Note that the declarations outside of the lambda should also be
+  // incorporated. Turning on the 'ForOverloadResolution' flag results in the
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cor3ntin wrote:

```suggestion
  // considered. Turning on the 'ForOverloadResolution' flag results in the
```


https://github.com/llvm/llvm-project/pull/83420