Can't find any Windows specific docs for ldc2.

I want to know which environment variables specific to Windows ldc2 listens to so as to find the linker and libs so as to speed up linking by not searching for a Visual Whatever installation every time.

Anyone?

On Tuesday, 16 October 2018 at 16:43:38 UTC, Carl Sturtivant wrote:
> Can't find any Windows specific docs for ldc2.
>
> I want to know which environment variables specific to Windows ldc2 listens to so as to find the linker and libs so as to speed up linking by not searching for a Visual Whatever installation every time.
>
> Anyone?

I have determined that the vcvars batch file that comes with the windows 10 sdk sets the following new variables for 64 bit development on windows 10 64-bit. It also adds to Path, which I would prefer to avoid. Some of these are obviously irrelevant, but which ones does ldc2 actually use to speed up linking?

I could use intuition and experiment, but it would be nice if someone would just point me to docs or tell me the answer.

CommandPromptType
DevEnvDir
ExtensionSdkDir
Framework40Version
FrameworkDir
FrameworkDir64
FrameworkVersion
FrameworkVersion64
INCLUDE
LIB
LIBPATH
Platform
UCRTVersion
UniversalCRTSdkDir
VCIDEInstallDir
VCINSTALLDIR
VCToolsInstallDir
VCToolsRedistDir
VCToolsVersion
VS150COMNTOOLS
VSCMD_ARG_HOST_ARCH
VSCMD_ARG_TGT_ARCH
VSCMD_ARG_app_plat
VSCMD_VER
VSINSTALLDIR
VisualStudioVersion
WindowsLibPath
WindowsSDKLibVersion
WindowsSDKVersion
WindowsSdkBinPath
WindowsSdkDir
WindowsSdkVerBinPath
__DOTNET_ADD_64BIT
__DOTNET_PREFERRED_BITNESS
__VSCMD_PREINIT_PATH

On Tuesday, 16 October 2018 at 16:43:38 UTC, Carl Sturtivant wrote:
> Can't find any Windows specific docs for ldc2.
>
> I want to know which environment variables specific to Windows ldc2 listens to so as to find the linker and libs so as to speed up linking by not searching for a Visual Whatever installation every time.

The LDC package contains a README.txt. Quoting: 'If run in a 'VS Native/Cross Tools Command Prompt' (i.e., if the environment variable VSINSTALLDIR is set), LDC skips the Visual C++ detection.'

Spawning a new VS command prompt ('shell', cmd.exe with env variables set up by the MS batch file) and invoking LDC in that shell is the preferred way of skipping that ~1-second linking overhead, at least that's how I do things all the time.
If for whatever reason you don't want all of those MS env variables, you'll just need VSINSTALLDIR to prevent LDC from autodetecting and then the env variables expected by the MS linker (LIB and LIBPATH may be enough, I don't remember).

On Tuesday, 16 October 2018 at 17:34:41 UTC, kinke wrote:
> [...]

PS:
* In case you haven't noticed, there are startmenu shortcuts to the VS command prompts, at least with a full VS installation, not sure about the Build Tools.
* PATH is also required, LDC invokes `link.exe`. Make sure there's no DMD link.exe in PATH. ;)

On Tuesday, 16 October 2018 at 17:38:48 UTC, kinke wrote:
> * PATH is also required, LDC invokes `link.exe`. Make sure there's no DMD link.exe in PATH. ;)

PPS: Not really required (e.g., with `-link-internally` or with `-linker=<path\to\link.exe>`). You can also specify the lib dirs as linker flags via `-L/LIBPATH:<dir1> -L/LIBPATH:<dir2>` in the LDC command line, so that you don't need that env variable either. You can put these switches into the etc\ldc2.conf file to make them implicit. All you should really need is setting VSINSTALLDIR to something non-empty.

On Tuesday, 16 October 2018 at 19:09:26 UTC, kinke wrote:
> On Tuesday, 16 October 2018 at 17:38:48 UTC, kinke wrote:
>> * PATH is also required, LDC invokes `link.exe`. Make sure there's no DMD link.exe in PATH. ;)
>
> PPS: Not really required (e.g., with `-link-internally` or with `-linker=<path\to\link.exe>`). You can also specify the lib dirs as linker flags via `-L/LIBPATH:<dir1> -L/LIBPATH:<dir2>` in the LDC command line, so that you don't need that env variable either. You can put these switches into the etc\ldc2.conf file to make them implicit. All you should really need is setting VSINSTALLDIR to something non-empty.

Thanks for all the very useful information! Much appreciated.

Based upon all this I tried first setting VSINSTALLDIR and adding to PATH the path to the linker. And setting LIB. (Apparently LIBPATH is for the compiler, not the linker.) This did the job! I'll put the path to the linker and the directories in LIB into switches in etc/ldc2.conf and I'll have a clean setup.

On Tuesday, 16 October 2018 at 20:14:03 UTC, Carl Sturtivant wrote:
> Based upon all this I tried first setting VSINSTALLDIR and adding to PATH the path to the linker. And setting LIB. (Apparently LIBPATH is for the compiler, not the linker.) This did the job! I'll put the path to the linker and the directories in LIB into switches in etc/ldc2.conf and I'll have a clean setup.

Specifically for persons new to D on windows who want to follow in these footsteps, the values needed proved to be as follows on 64 bit Windows 10.

I obtained these by running the commands listed below in a `x64 Native Tools Command Prompt for VS 2017` under `Visual Studio 2017\Visual Studio Tools\VC` from the start menu. Probably you should do that.


VSINSTALLDIR
from `echo %VSINSTALLDIR%`
C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\

LIB
from `echo %LIB%`
C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Tools\MSVC\14.15.26726\lib\x64;C:\Program Files (x86)\Windows Kits\10\lib\10.0.17134.0\ucrt\x64;C:\Program Files (x86)\Windows Kits\10\lib\10.0.17134.0\um\x64;

PATH --- addition to PATH needed to find link.exe
from `where link`
C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Tools\MSVC\14.15.26726\bin\Hostx64\x64\