Notice how that page describes how to configure the toolchain using XML. That's the thing I don't like -- instead of just building up an args list like cl.exe, I need to write my own intermediate tooling that synthesizes a .csproj and spits it out into the build sandbox before launching their magic do-everything binary.

There's clearly something else underneath, the <LinkerArg> element is exactly what I would want to generate when running link.exe, but most of the configuration options are wrapped in a layer of gunk.

Ideally it would be possible to invoke a command directly to convert a bunch of *.cs files into a .dll (or .a), then I could use existing logic to link it with link.exe (or ld).

FWIW, the relevant gunk: C:\Program Files\dotnet\sdk\7.0.100\Sdks\Microsoft.DotNet.ILCompiler\build\Microsoft.NETCore.Native.targets

And C:\Program Files\dotnet\sdk\7.0.100\Sdks\Microsoft.DotNet.ILCompiler\build\Microsoft.NETCore.Native.Unix.targets (where the linker is selected)

See the area around and after this chunk

      <CustomLinkerArg Include="&quot;$(NativeObject)&quot;" />
      <CustomLinkerArg Include="-o &quot;$(NativeBinary)&quot;" Condition="'$(TargetOS)' != 'windows'" />
      <CustomLinkerArg Include="/OUT:&quot;$(NativeBinary)&quot;" Condition="'$(TargetOS)' == 'windows'" />
      <CustomLinkerArg Include="/DEF:&quot;$(ExportsFile)&quot;" Condition="'$(TargetOS)' == 'windows' and $(ExportsFile) != ''" />
      <CustomLinkerArg Include="/LIBPATH:&quot;%(AdditionalNativeLibraryDirectories.Identity)&quot;" Condition="'$(TargetOS)' == 'windows' and '@(AdditionalNativeLibraryDirectories->Count())' &gt; 0" />
      <CustomLinkerArg Include="-exported_symbols_list &quot;$(ExportsFile)&quot;" Condition="'$(TargetOS)' == 'OSX' and $(ExportsFile) != ''" />
      <CustomLinkerArg Include="-Wl,--version-script=$(ExportsFile)" Condition="'$(TargetOS)' != 'windows' and '$(TargetOS)' != 'OSX' and $(ExportsFile) != ''" />
      <CustomLinkerArg Condition="Exists('$(_Win32ResFile)')" Include="&quot;$(_Win32ResFile)&quot;" />
      <CustomLinkerArg Include="@(LinkerArg)" />

The old ways of command line arguments are no longer available, nowadays project files have to be used.