Cannot correctly build Luau - disables a required flag /EHsc when vanilla cmake does not

[LoganDark]

I'm going to open this as an issue because fundamentally this seems to be a problem with cmake-rs - as cmake on its own builds Luau just fine.

Using cmake . and then cmake --build . has no issue from a Windows command prompt, but cmake-rs does this:

Microsoft (R) Build Engine version 16.10.2+857e5a733 for .NET Framework
  Copyright (C) Microsoft Corporation. All rights reserved.
    Checking Build System
    Ast.cpp
    lapi.cpp
    laux.cpp
    Confusables.cpp
    lbaselib.cpp
    lbitlib.cpp
    lbuiltins.cpp
    Lexer.cpp
    lcorolib.cpp
    ldblib.cpp
    ldebug.cpp
    ldo.cpp
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1245,1): error C2220: the following warning is treated as an error [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1275): message : see reference to function template instantiation 'void std::vector<Item,std::allocator<Item>>::_Resize_reallocate<_Ty2>(const unsigned __int64,const _Ty2 &)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry,
                _Ty2=Luau::AstNameTable::Entry
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1275): message : see reference to function template instantiation 'void std::vector<Item,std::allocator<Item>>::_Resize_reallocate<_Ty2>(const unsigned __int64,const _Ty2 &)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry,
                _Ty2=Luau::AstNameTable::Entry
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1295): message : see reference to function template instantiation 'void std::vector<Item,std::allocator<Item>>::_Resize<_Ty>(const unsigned __int64,const _Ty2 &)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry,
                _Ty=Luau::AstNameTable::Entry,
                _Ty2=Luau::AstNameTable::Entry
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1295): message : see reference to function template instantiation 'void std::vector<Item,std::allocator<Item>>::_Resize<_Ty>(const unsigned __int64,const _Ty2 &)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry,
                _Ty=Luau::AstNameTable::Entry,
                _Ty2=Luau::AstNameTable::Entry
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1293): message : while compiling class template member function 'void std::vector<Item,std::allocator<Item>>::resize(const unsigned __int64,const _Ty &)' [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry,
                _Ty=Luau::AstNameTable::Entry
            ]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\include\Luau/DenseHash.h(46): message : see reference to function template instantiation 'void std::vector<Item,std::allocator<Item>>::resize(const unsigned __int64,const _Ty &)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry,
                _Ty=Luau::AstNameTable::Entry
            ]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\include\Luau/DenseHash.h(234): message : see reference to class template instantiation 'std::vector<Item,std::allocator<Item>>' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Item=Luau::AstNameTable::Entry
            ]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\include\Luau/DenseHash.h(286): message : see reference to class template instantiation 'Luau::detail::DenseHashTable<Key,Key,Key,Luau::detail::ItemInterfaceSet<Key>,Hash,Eq>' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Key=Luau::AstNameTable::Entry,
                Hash=Luau::AstNameTable::EntryHash,
                Eq=std::equal_to<Luau::AstNameTable::Entry>
            ]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\include\Luau/Lexer.h(157): message : see reference to class template instantiation 'Luau::DenseHashSet<Luau::AstNameTable::Entry,Luau::AstNameTable::EntryHash,std::equal_to<Key>>' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                Key=Luau::AstNameTable::Entry
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(1245,1): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
    Location.cpp
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\VM\src\ldo.cpp(118,5): error C2220: the following warning is treated as an error [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.VM.vcxproj]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\VM\src\ldo.cpp(118,5): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.VM.vcxproj]
    lfunc.cpp
    lgc.cpp
    linit.cpp
    lmathlib.cpp
    lmem.cpp
    Parser.cpp
    lobject.cpp
    loslib.cpp
    lperf.cpp
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\src\Parser.cpp(154,5): error C2220: the following warning is treated as an error [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\src\Parser.cpp(154,5): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
    lstate.cpp
    lstring.cpp
    lstrlib.cpp
    Generating Code...
    StringUtils.cpp
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(765,1): error C2220: the following warning is treated as an error [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(739): message : see reference to function template instantiation 'std::basic_string_view<char,std::char_traits<char>> *std::vector<std::string_view,std::allocator<std::string_view>>::_Emplace_reallocate<_Ty>(std::basic_string_view<char,std::char_traits<char>> *const ,_Ty &&)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                _Ty=std::basic_string_view<char,std::char_traits<char>>
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(747): message : see reference to function template instantiation 'std::basic_string_view<char,std::char_traits<char>> *std::vector<std::string_view,std::allocator<std::string_view>>::_Emplace_reallocate<_Ty>(std::basic_string_view<char,std::char_traits<char>> *const ,_Ty &&)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                _Ty=std::basic_string_view<char,std::char_traits<char>>
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(761): message : see reference to function template instantiation '_Ty &std::vector<_Ty,std::allocator<_Ty>>::emplace_back<std::basic_string_view<char,std::char_traits<char>>>(std::basic_string_view<char,std::char_traits<char>> &&)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                _Ty=std::string_view
            ]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(759): message : while compiling class template member function 'void std::vector<std::string_view,std::allocator<std::string_view>>::push_back(_Ty &&)' [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                _Ty=std::string_view
            ]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\src\StringUtils.cpp(111): message : see reference to function template instantiation 'void std::vector<std::string_view,std::allocator<std::string_view>>::push_back(_Ty &&)' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
            with
            [
                _Ty=std::string_view
            ]
  C:\Users\LoganDark\CLionProjects\luau\luau-sys\luau\Ast\src\StringUtils.cpp(91): message : see reference to class template instantiation 'std::vector<std::string_view,std::allocator<std::string_view>>' being compiled [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
  C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30037\include\vector(765,1): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc [C:\Users\LoganDark\CLionProjects\luau\target\debug\build\luau-sys-7f8bb85230e5cd51\out\build\Luau.Ast.vcxproj]
    Generating Code...
    Compiling...
    ltable.cpp
    ltablib.cpp
    ltm.cpp
    lutf8lib.cpp
    lvmexecute.cpp
    lvmload.cpp
    lvmutils.cpp
    Generating Code...

(from luau-lang/luau#123 - where the owners have cut off all outside interaction, so I can't even open a PR anymore)

The exact commands cmake-rs runs are:

"cmake" "C:\\Users\\LoganDark\\CLionProjects\\luau\\luau-sys\\luau" "-G" "Visual Studio 16 2019" "-Thost=x64" "-Ax64" "-DLUAU_BUILD_CLI=OFF" "-DLUAU_BUILD_TESTS=OFF" "-DCMAKE_INSTALL_PREFIX=C:\\Users\\LoganDark\\CLionProjects\\luau\\target\\debug\\build\\luau-sys-7f8bb85230e5cd51\\out" "-DCMAKE_C_FLAGS= -nologo -MD -Brepro" "-DCMAKE_C_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_CXX_FLAGS= -nologo -MD -Brepro" "-DCMAKE_CXX_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_ASM_FLAGS= -nologo -MD -Brepro" "-DCMAKE_ASM_FLAGS_DEBUG= -nologo -MD -Brepro" "-DCMAKE_BUILD_TYPE=Debug"
"cmake" "--build" "." "--target" "ALL_BUILD" "--config" "Debug" "--parallel" "12"

Something in here is causing the build to fail. Note that it succeeds without issue in WSL, it's only Cursed Windows that has this problem.

[AregevDev]

The same thing happens to me with assimp.
I just add the flag for now