Anticipate the usage of Visual Studio 2017 Developer Command Prompt?

[Andre Pany]

On Saturday, 4 November 2017 at 09:39:02 UTC, Rainer Schuetze 
wrote:
>
>
> On 03.11.2017 21:51, Andre Pany wrote:
>> On Friday, 3 November 2017 at 11:52:10 UTC, Andre Pany wrote:
>>> [...]
>> 
>> I have an idea which solves several problems.
>> 
>> Current state:
>> The dmd windows archive has a folder "bin" with a 32 bit dmd 
>> compiler which is able to create x86 and x86_64 applications. 
>> By default the dmd compiler creates 32 bit applications using 
>> the optlink link.exe contained also in this folder.
>> 
>> Idea:
>> Within the folder "bin64" the 64 bit dmd compiler could be 
>> shipped within the dmd windows archive. I assume the 64 bit 
>> dmd compiler is able to create x86 and x86_64 applications. In 
>> folder "bin64" no optlink link.exe should be available.
>> The usage of either the microsoft link.exe or another linker 
>> (maybe the one from LDC) is anticipated. The 64 bit dmd 
>> compiler could have the option -m64 set as default.
>> 
>> The user can decide whether he wants to use the "stable" dmd 
>> compiler with usage of optlink or he want to use the 64 bit 
>> dmd compiler which is open for other linkers than optlink by 
>> simply setting his path variable to bin or to bin64.
>> 
>> Using this approach:
>> - DMD compiler is working out of the box for the VS Developer 
>> Command Prompt - no need to rename the optlink link.exe
>> - A 64 bit dmd compiler is shipped which solves issues on 
>> large D projects
>> 
>> What do you think?
>> 
>> Kind regards
>> André
>
> Finding the wrong linker seems to happen quite often, but I 
> wonder why:
>
> sc.ini usually has the absolute path to the linker set via the 
> LINKCMD variable, so finding the correct executable should not 
> be a problem if the installer has set things up correctly. If 
> extracted from the zip there are also defaults that might not 
> work but should not find the wrong linker.
>
> Is it the result of trying to fix the sc.ini manually?
>
> The problem with overriding the LIB environment variable is 
> that optlink and the MS linker both use it, but stumble over 
> the libraries for the other linker due to different file 
> formats.
>
> I think the best option forward is to not rely on the installer 
> to find the correct setup at installation time, but detect the 
> available linker and its environment before invoking it:
>
> - if the environment is already set up via vcvarsall, i.e. 
> VCINSTALLDIR set, use that to call the approriate linker
>
> - if VCINSTALLDIR is not set, use the registry to find the best 
> fit, i.e. highest available VS version
>
> - some way to override the automatism should be available, too.
>
> We might also be able to provide some fallback if no VS 
> installation is found, based on the LLVM linker, but with 
> limited C runtime/platform library support.

I would say, by executing vcvarsall the user showed his intention 
to use the coff libraries and the Microsoft linker for the actual 
console session instead of the omf libraries.

I see a disadvantage by detecting the vc installation directory / 
lib directories. All paths are specific for the vs version. If 
there is x new vs version we are always behind.

But Microsoft has a solution for this problem. Vcvarsall sets the 
linker as first element of the path variable and the lib env 
variable points to the right folder. This solution will work for 
old vs version and any upcoming version.

I set linkcmd to "link.exe". Unfortunately the link.exe in the 
dmd bin folder has precedence over the path env variable.

Kind regards
Andre