[llvm-dev] LLVMSymbolizer can't find DIA library

[via llvm-dev]

> I'm using Visual Studio 2017 (14.0) and it looks like I do have
> the DIA SDK installed, but llvm-mc is crashing and I keep seeing:
> 
> LLVMSymbolizer: error reading file: PDB Error: DIA is not installed on the
> system
> 
> Do I need to set some environment variable, or something?

And the answer is:

1) Delete CMakeCache.txt
2) run "%VS140COMNTOOLS%\vsvars32.bat"
3) run CMake
4) won't hurt to `touch llvm\lib\DebugInfo\PDB\PDB.cpp`
5) build

CMake will set LLVM_ENABLE_DIA_SDK=ON automatically, *if* you have
VSINSTALLDIR defined when you run CMake, and your CMakeCache.txt 
doesn't have LLVM_ENABLE_DIA_SDK=OFF.

It's not at all clear how to document this in the Getting Started
pages.
--paulr