llvm dev - Oct 2019 - Recent LLVM Build Attempt -- obj.ClangAST.vcxproj Failed to Build

I configured with this command:
"
cmake ../llvm -G"Visual Studio 16 2019" -A Win32 -Thost=x64
-DLLVM_ENABLE_EH=ON -DCMAKE_BUILD_TYPE=Release -DLLVM_USE_CRT_RELEASE=MT
-DLLVM_ENABLE_RTTI=ON
-DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;lld;libcxx;libcxxabi"
-DCMAKE_CXX_FLAGS="/permissive-
/D_SILENCE_ALL_CXX17_DEPRECATION_WARNINGS" -DCMAKE_CXX_STANDARD=17
"
and when building the target ALL_BUILD.vcxproj I redirected the output to a
file.  I'm attaching that file to this message.  Name of the file is
build.log.  I'm attaching CMakeCache.txt and CMakeOutput.log for reference.

Any help is appreciated.  Thanks in advance.
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I see two interesting things in your configuration:
- You are passing  -DCMAKE_CXX_STANDARD=17. Is there a reason for that?
Using fewer options is generally more likely to result in a successful
build.
- You are using MSVC build 14.23.28105. This is newer than what I am using
and our bots are using. I will have to try upgrading myself.

This is the error in question isolated:
C:\llvm-project\clang\lib\AST\Interp\ByteCodeStmtGen.cpp(239,1): error
C2872: 'Optional': ambiguous symbol
[C:\llvm-project\build\tools\clang\lib\AST\obj.clangAST.vcxproj]
C:\llvm-project\clang\lib\AST\Interp\ByteCodeStmtGen.cpp(22,57): message :
could be 'Optional = llvm::Optional<T>'
[C:\llvm-project\build\tools\clang\lib\AST\obj.clangAST.vcxproj]

This ByteCodeStmtGen.cpp file is relatively new, so that could be
interesting.

On Wed, Oct 30, 2019 at 10:17 AM Osman Zakir via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> I configured with this command:
> "
> cmake ../llvm -G"Visual Studio 16 2019" -A Win32 -Thost=x64
> -DLLVM_ENABLE_EH=ON -DCMAKE_BUILD_TYPE=Release -DLLVM_USE_CRT_RELEASE=MT
> -DLLVM_ENABLE_RTTI=ON
>
-DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;lld;libcxx;libcxxabi"
> -DCMAKE_CXX_FLAGS="/permissive-
/D_SILENCE_ALL_CXX17_DEPRECATION_WARNINGS"
> -DCMAKE_CXX_STANDARD=17
> "
> and when building the target ALL_BUILD.vcxproj I redirected the output to
> a file.  I'm attaching that file to this message.  Name of the file is
> build.log.  I'm attaching CMakeCache.txt and CMakeOutput.log for
reference.
>
>
> Any help is appreciated.  Thanks in advance.
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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I hope I'm not being too presumptuous or anything when I say this: could you
guys please review the obj.ClangAST.vcxproj project and try to fix the ambiguity
error?

Reid asked me why I'm using C++17.  I just want to use the latest released
standard.  Most if it still compiles anyway.  So I'll stick with it.
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