Discussion: Fallback CoreCLR build to OSX/x64 when building for iOS

[akoeplinger]

I'm working on a branch that adds an iOS target OS to the build system.

This causes an issue for the CoreCLR build because it doesn't know how to build for that target and until #32613 is fixed we need the CoreCLR build for the libraries build.

My current thinking was that the build can simply fallback to OSX.x64 in that case as it's the only platform where iOS can be built. I've implemented that in akoeplinger@23cca6b.

@ViktorHofer asked me to open a discussion issue so we can decide whether that is the correct approach and get some input from @jkotas.

[jkotas]

fallback to OSX.x64

That does not sound like the right approach to me. We should not building CoreCLR at all when building for iOS.

[akoeplinger]

@jkotas I agree but the libraries build requires CoreCLR at the moment.

[jkotas]

What does the libraries build require from CoreCLR?

[jkotas]

It should be just System.Private.CoreLib and it should be trivial to switch libraries to consume System.Private.CoreLib from Mono.

[akoeplinger]

I haven't looked into that but if it's trivial then yeah we should go that way instead.

@ViktorHofer can you take a look?

[steveisok]

From what I've seen it requires System.Private.CoreLib, its pdb and dwarf file.

[akoeplinger]

There's more logic that checks for CoreCLR artifacts like this one:

runtime/eng/liveBuilds.targets

Line 91 in 58cf146

<Error Condition="!Exists('$(CoreCLRArtifactsPath)')" Text="The CoreCLR artifacts path does not exist '$(CoreCLRArtifactsPath)'. The CoreCLR subset category must be built before building this project." />

I'm not sure if it's the only place.

[ViktorHofer]

We also need the Microsoft.NET.Sdk.IL (ilasm, ildasm)

[steveisok]

Is it just ilasm / ildasm? If so, can we use a fixed version for them?

[ViktorHofer]

I believe we aren't using a live version yet, so this shouldn't be an issue at the moment: #1137.

[akoeplinger]

Ok, given that the fallback approach isn't desirable and we should instead fix the libraries build to no longer require CoreCLR let's continue the discussion in #32613.