Possible docfx issue with latest SDK

[jskeet]

I'm using SDK 6.0.400 now, and I've just run into a problem running builddocs.sh:

[22-08-15 04:04:51.480]Warning:[ExtractMetadata](C:/Users/jonskeet/GitHub/googleapis/google-cloud-dotnet/apis/Google.Cloud.Functions.V2/Google.Cloud.Functions.V2/Google.Cloud.Functions.V2.csproj)Workspace failed with: [Failure] Msbuild failed when processing the file 'C:\Users\jonskeet\GitHub\googleapis\google-cloud-dotnet\apis\Google.Cloud.Functions.V2\Google.Cloud.Functions.V2\Google.Cloud.Functions.V2.csproj' with message: Method not found: 'System.ReadOnlySpan`1<Char> Microsoft.IO.Path.GetFileName(System.ReadOnlySpan`1<Char>)'.

Will try updating to a later docfx version...

[jskeet]

Looks like this is basically dotnet/docfx#8136

I'm hoping there'll be a new docfx release soon to fix this, but if not we may need to patch things - or pin to an earlier SDK, somehow...

[jskeet]

This shouldn't affect releasing though, so long as we know not to update to a more recent SDK in Kokoro.

[jskeet]

There's a potential workaround, which is to build the docs from the built DLLs instead of the project files.

We'd probably want to go via a "dotnet publish" step so that all the DLLs (with the right versions) are in the right directory. However, I think it's probably best to save that approach for a rainy day if we need it.

[jskeet]

I've added a workaround to #8136. We can use that to get local builds working temporarily. Hopefully there'll be a new release soon.