LLVM Compiler Toolchain

Note: the extension only seems to work in VS2019 if VS2017 is also installed (https://llvm.org/PR42290). VS2019 users may want to look at Clang/LLVM Support in Visual Studio instead.

This extension allows clang to be used as a drop in replacement for the standard Visual Studio compiler in existing C and C++ projects. Simply go to Project -> Settings -> General, choose "llvm" as the toolchain, and you are ready to go!

Note that you will need to install LLVM separately. If you want to use a custom built version of LLVM that you have not installed, a property page is added to the project settings UI to allow you to choose an explicit clang binary.

Since clang is a drop-in replacement for MSVC, all compiler options and projects settings that you've selected (with a couple of exceptions) should "just work".

Exceptions:

1. You may need to disable precompiled headers
2. MSVC LTCG and PGO are incompatible with clang. As such, you will need to disable these options.
3. Clang does not support some of the most obscure options of cl. You will get a warning or error if you try to make use of them.

Update History

8/30/2018:

1. LLD is now supported! You can choose to enable either LLD, clang-cl, or both.
2. Based on user feedback, project settings are added that enable you to specify additional compiler / linker options only when the LLVM version of the corresponding tool is in use. This is helpful if you switch back and forth between toolchains.
3. Removed the warnings about several ignored compiler options.
4. Due to the structure of a VC project file and the nature of the changes required to get the options working, it's possible that a vcxproj that was set to use this toolchain on an earlier version will not smoothly transition. If that happens, set each value in the LLVM page to a different value (to force it to be dirty), then save, then set the values back to the original values again. Hopefully this is the last time this will happen.