[clang] [Clang] Handle ?: operator in fold expression (PR #164019)

[Azmat Yusuf via cfe-commits]

azmat-y wrote:

> I’m not convinced this is the right approach; what if we have e.g.
> 
> ```c++
> template <typename ... T>
> void foo(T... Params) {
>   ([&]{ Params ?: 1; }(), ...);
> }
> ```
> 
> We still crash on this and I’m sure `commonExpr` would still be pack-dependent in this case, but we don’t want this to become invalid.
> 
> I wonder if we should just delete the assertion in `computeDependence(OpaqueValueExpr*)`.

Sorry for late response. Yeah that should stay valid  `commonExpr` does remain pack dependent , though something weird is  happening with my build. It compiles your example without any errors even though `commonExpr` is pack dependent, the control flow moves to ExprError() but after continuing with the execution no error is raised. 

Could something else suppress `ExprError()`?

https://github.com/llvm/llvm-project/pull/164019