Assembly (project) conventions should support Directory.Build.Props & Directory.Build.Targets

[flakey-bit]

MSBuild allows templating / "meta-programming" of csproj files via Directory.Build.Props & Directory.Build.Targets - see this page for more background but basically

• Directory.Build.Props allows setting default property values across all projects in the directory (recursively)
• Directory.Build.Targets allows setting dependant property values (i.e. incorporating customizations from individual projects)

At least that's my understanding - haven't used Directory.Build.Targets myself.

Existing conventions like MustNotReferenceDllsFromTransientOrSdkDirectoriesConventionSpecification that parse the project XML are unaware of this functionality and are arguably broken as a result.

For example, a Directory.Build.Props file could add an (assembly) Reference w/ a HintPath to all projects in the directory, which MustNotReferenceDllsFromTransientOrSdkDirectoriesConventionSpecification would be unaware of when examing the project XML, leading to false-negative.

[flakey-bit]

Ironically, Directory.Build.Props & Directory.Build.Targets files make keeping things consistent easier - however they make checking things are consistent harder 🤔

[andrewabest]

Good spotting @flakey-bit. Fixing this would be reasonably straight-forward. I'll either get to it eventually, or someone can pick it up, I've labelled it a good first issue if someone happens to come by and wants to contribute.

[flakey-bit]

Fixing this would be reasonably straight-forward

@andrewabest do you have some thoughts in mind as to how we could address this?

[andrewabest]

I was thinking you would essentially have to replicate what MSBuild does - for any project, locate the directory.build.props file closest to it, and consider its values in applying the convention (docs)

It can get a bit complex, but we could support the simpler version of it: don't support multiple props files, just support the nearest one per project.

[flakey-bit]

I think you're suggesting that we should fully evaluate the project XML and pass the "composed" csproj (i.e. post-application of Directory.Build.Props & Directory.Build.Targets) to Conventional conventions (in other words, treating it as a templating system).

If so, I agree 👍

It would be neat if we could do so by leveraging MSBuild, rather than reimplementing it. If we can find a way to do that I guess we'd get full support (multiple props files etc) "for free".

[andrewabest]

Yup, strong agree there. I know dotnet-affected uses MsBuild internally (example), so it is very possible that that is a doable thing.