Build Subset Dependencies

[MarcasRealAccount]

When using build.cmd or build.sh to build certain subsets, you might end up with a few errors stating that you're missing executables.
That's because build.cmd and build.sh expects all subset dependencies are already built, which to my belief is very bad.

For instance building Libs requires that you first build some things from both Clr and Host.

I think build.cmd and build.sh should not only build the target subset but also that subset's dependencies, such that instead of doing
build.cmd Clr+Host+Libs because you only wanted the Libs, you'd instead just do build.cmd Libs and it would build the dependencies from Clr and Host.

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Issue Details

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When using build.cmd or build.sh to build certain subsets, you might end up with a few errors stating that you're missing executables.
That's because build.cmd and build.sh expects all subset dependencies are already built, which to my belief is very bad.

For instance building Libs requires that you first build some things from both Clr and Host.

I think build.cmd and build.sh should not only build the target subset but also that subset's dependencies, such that instead of doing
build.cmd Clr+Host+Libs because you only wanted the Libs, you'd instead just do build.cmd Libs and it would build the dependencies from Clr and Host.

Author:	MarcasRealAccount
Assignees:	-
Labels:	area-Infrastructure-libraries, untriaged
Milestone:	-

[safern]

Thanks, @MarcasRealAccount for your input, we appreciate it.

In my opinion, I think that would slow down innerloop and complicate things. There are various scenarios where you don't want to build dependencies for a subset, say CI scenarios, or even a scenario where I already have Clr built locally and I'm just iterating over Libs, I don't want to spend time building Clr and just build Libs.

We could perhaps enable this if we fixed our incremental story and make it super fast to incrementally build all subsets, which we are investing on, but I don't know how much time people would waste building things they no longer need to build.

@dotnet/runtime-infrastructure for more thoughts/ideas.

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Tagging subscribers to this area: @dotnet/runtime-infrastructure
See info in area-owners.md if you want to be subscribed.

Issue Details

---

When using build.cmd or build.sh to build certain subsets, you might end up with a few errors stating that you're missing executables.
That's because build.cmd and build.sh expects all subset dependencies are already built, which to my belief is very bad.

For instance building Libs requires that you first build some things from both Clr and Host.

I think build.cmd and build.sh should not only build the target subset but also that subset's dependencies, such that instead of doing
build.cmd Clr+Host+Libs because you only wanted the Libs, you'd instead just do build.cmd Libs and it would build the dependencies from Clr and Host.

Author:	MarcasRealAccount
Assignees:	-
Labels:	area-Infrastructure, untriaged
Milestone:	-