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How do I avoid the unresolved external symbol _mainCRTStartup error when using the MSVC toolchain (ex: CL.EXE) from within an MSYS environment?

Details:

I started a "VS2013 x64 Native Tools Command Prompt" and the launched C:\msys64\msys2.exe from there.

In my MSYS session I get results like this:

user@host MSYS /c/libpostal/libpostal
$ "/c/Program Files (x86)/Microsoft Visual Studio 12.0/VC/bin/amd64/vcvars64.bat"

user@host MSYS /c/libpostal/libpostal
$ cl "-nologo" "conftest.c" "-link" "-SUBSYSTEM:CONSOLE"
conftest.c
LINK : error LNK2001: unresolved external symbol _mainCRTStartup
conftest.exe : fatal error LNK1120: 1 unresolved externals

user@host MSYS /c/libpostal/libpostal
$ cat conftest.c
/* confdefs.h */
#define PACKAGE_NAME "libpostal"
#define PACKAGE_TARNAME "libpostal"
#define PACKAGE_VERSION "1.0.0"
#define PACKAGE_STRING "libpostal 1.0.0"
#define PACKAGE_BUGREPORT ""
#define PACKAGE_URL ""
#define PACKAGE "libpostal"
#define VERSION "1.0.0"
/* end confdefs.h.  */

int
main ()
{

  ;
  return 0;
}

user@host MSYS /c/libpostal/libpostal
$ echo $PATH
/c/Program Files (x86)/Microsoft Visual Studio 12.0/VC/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/c/Windows/System32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0/:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl

If I try to put the same "cl" command into the "VS2013 x64 Native Tools Command Prompt", I get the expected result instead:

C:\libpostal\libpostal>cl "-nologo" "conftest.c" "-link" "-SUBSYSTEM:CONSOLE"
conftest.c

C:\libpostal\libpostal>cl "/nologo" "conftest.c" "/link" "/SUBSYSTEM:CONSOLE"
conftest.c

C:\libpostal\libpostal>conftest.exe

C:\libpostal\libpostal>echo %PATH%
C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\CommonExtensions\Microsoft\TestWindow;C:\Program Files (x86)\MSBuild\12.0\bin\amd64;C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\BIN\amd64;C:\Windows\Microsoft.NET\Framework64\v4.0.30319;C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\VCPackages;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\Tools;C:\Program Files (x86)\HTML Help Workshop;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Team Tools\Performance Tools\x64;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Team Tools\Performance Tools;C:\Program Files (x86)\Windows Kits\8.1\bin\x64;C:\Program Files (x86)\Windows Kits\8.1\bin\x86;C:\Program Files (x86)\Microsoft SDKs\Windows\v8.1A\bin\NETFX 4.5.1 Tools\x64\;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\CommonExtensions\Microsoft\TestWindow;C:\Program Files (x86)\MSBuild\12.0\bin\amd64;C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\BIN\amd64;C:\Windows\Microsoft.NET\Framework64\v4.0.30319;C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\VCPackages;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\Tools;C:\Program Files (x86)\HTML Help Workshop;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Team Tools\Performance Tools\x64;C:\Program Files (x86)\Microsoft Visual Studio 12.0\Team Tools\Performance Tools;C:\Program Files (x86)\Windows Kits\8.1\bin\x64;C:\Program Files (x86)\WindowsKits\8.1\bin\x86;C:\Program Files (x86)\Microsoft SDKs\Windows\v8.1A\bin\NETFX 4.5.1 Tools\x64\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Microsoft Dynamics AX\60\Client\Bin\;C:\Program Files\Microsoft Dynamics AX\60\BusinessConnector\Bin\;C:\Program Files (x86)\Microsoft SQL Server\Client SDK\ODBC\110\Tools\Binn\;C:\Program Files (x86)\Microsoft SQL Server\120\Tools\Binn\;C:\Program Files (x86)\Microsoft SQL Server\120\DTS\Binn\;C:\Program Files (x86)\Microsoft SQL Server\120\Tools\Binn\ManagementStudio\;C:\Program Files\Microsoft\Web Platform Installer\;C:\Program Files(x86)\Microsoft ASP.NET\ASP.NET Web Pages\v1.0\;C:\Program Files\Microsoft SQL Server\110\Tools\Binn\;C:\Program Files (x86)\Windows Kits\8.1\Windows Performance Toolkit\;C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.0\;C:\Program Files\Microsoft SQL Server\120\Tools\Binn\;C:\Program Files\Git\cmd;C:\D\dmd2\windows\bin;C:\msys64;C:\msys64\usr\local\bin;C:\msys64\usr\bin;C:\msys64\bin;C:\msys64\opt\bin

This happened while I was trying to use cccl to build a posix project (libpostal) using the MSVC toolchain so I can link it with other MSVC code. As such, any answers involving Visual Studio GUI will probably not be very helpful: I need to figure out how to make it work from within the MSYS2/MSYS64 environment.

In the MSYS example I intentionally moved /c/Program Files (x86)/Microsoft Visual Studio 12.0/VC/bin to the beginning of my $PATH to avoid selecting the wrong executables. I originally received the same results (exact same error message) when it was at the end of the $PATH instead.

chadjoan
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1 Answers1

0

After checking everything in agonizing detail, I found the problem:

When C:\msys64\msys2.exe is executed from the "VS2013 x64 Native Tools Command Prompt", the $PATH variable will end up containing /c/Program Files (x86)/Microsoft Visual Studio 12.0/VC/bin, but that is the wrong directory for 64-bit work. Instead the path should contain /c/Program Files (x86)/Microsoft Visual Studio 12.0/VC/bin/amd64. Once I did that substitution, cl.exe worked fine.

Running vcvars64.bat from within the MSYS environment will not fix the $PATH. The above substitution has to be done manually or from a custom startup script like ~/.bashrc.

chadjoan
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