[PATCH] D151557: [ADT] Fix DenseMapInfo<variant>::isEqual to delegate to DenseMapInfo, not ==

[Sam McCall via Phabricator via llvm-commits]

sammccall marked an inline comment as done.
sammccall added inline comments.


================
Comment at: llvm/include/llvm/ADT/DenseMapInfo.h:354-356
+    return std::visit(detail::EqVisitor{detail::variantGetDynamic(
+                          RHS, std::make_index_sequence<sizeof...(Ts)>{})},
+                      LHS);
----------------
IncludeGuardian wrote:
> I think we may be able to use `std::visit` twice and rely on the type of the parameter in the second visit matching the original type of the value we cast to `const void *`.
> 
> ```
>     const void *ErasedLHSValue = std::visit([](const auto& LHSValue){
>         return static_cast<const void *>(&LHSValue);
>     }, l);
> 
>     return std::visit([=](const auto& RHSValue){
>         using T = std::remove_reference_t<decltype(RHSValue)>;
>         return DenseMapInfo<T>::isEqual(*static_cast<T *>(ErasedLHSValue), RHSValue);
>     }, r);
> ```
Right! I always forget that auto-params in lambdas are good for something other than saving typing :-)


Repository:
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  https://reviews.llvm.org/D151557/new/

https://reviews.llvm.org/D151557