[PATCH] D155431: [CMake] Clean up old code for handling MSVC runtime setting the old way

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo added a comment.

In D155431#4651678 <https://reviews.llvm.org/D155431#4651678>, @yurybura wrote:

>> Are you saying that this gets added automatically by CMake in this variable, or that it is set manually by your build configuration? I don't think it's added automatically by CMake.
>
> I'm saying that VCPKG adds these compiler flags.

And I'm saying that it's redundant.

>> The point is that by switching `CMAKE_MSVC_RUNTIME_LIBRARY` to the right choice, debug/non-debug, the define `_DEBUG` gets added automatically by the compiler if building in a debug mode. You shouldn't be adding that manually.
>
> As I understand `_DEBUG` is not added by default. How to add it for Debug config for the whole LLVM/Clang build but exclude adding it to `compiler-rt` or `libcxx`?

Why do you feel that you need to add `_DEBUG` at all?

If you set `CMAKE_MSVC_RUNTIME_LIBRARY` to a debug CRT, this define gets added automatically by the compiler. (And conversely, if something further down the build chain chooses to override `CMAKE_MSVC_RUNTIME_LIBRARY`, there's no conflicting `_DEBUG` define either.)


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  https://reviews.llvm.org/D155431/new/

https://reviews.llvm.org/D155431