Ldc ImportC preprocessor failure (wrong option syntax) on Windows

[Bastiaan Veelo]

On Tuesday, 4 February 2025 at 09:57:27 UTC, Richard (Rikki) 
Andrew Cattermole wrote:
> On 04/02/2025 10:50 PM, Bastiaan Veelo wrote:
>> Hi,
>> 
>> On my personal machine everything works fine, but our CI build 
>> machine suffers from this error:
>> ```
>> clang-cl.exe: warning: unknown argument ignored in clang-cl '- 
>> target' (did you mean '--target='?) [-Wunknown-argument]
>> clang-cl.exe: error: no such file or directory: 
>> 'x86_64-pc-windows-msvc'
>> ```
>> 
>> I have the impression that options are given as the Microsoft 
>> preprocessor expects them, but that the clang preprocessor is 
>> called instead. I think that on my personal machine the 
>> Microsoft preprocessor is called, which is also what I would 
>> expect, but I don't know of a way to verify that; the workings 
>> of ImportC are rather opaque.
>
> ldc and dmd have differing behaviors.
>
> https://github.com/ldc-developers/ldc/blob/master/driver/cpreprocessor.cpp
>
> And yes it prefers clang-cl.
>
> Which means this is a bug.

It could be a bug, but locally I use the same version (ldc 
1.39.0) and it works fine... Thanks for pointing to the driver 
source, maybe I can work out what it is doing.