Update convention how to ref&pkg an analyzer again

[ViktorHofer]

d3af492 made it possible to reference
and package an analyzer via the same msbuild item by setting custom
metadata.

While reviewing other places that could use the AnalyzerReference item,
I realized that using this custom item doesn't provide much value and
creates an artificial difference to the rest of the stack and our customers
as we don't adhere to our own documentation.

Instead, IMHO it makes much more sense to keep using a
ProjectReference item with the documented set of required metadata, to
reference an analyzer and just define an additional custom metadata to
support packaging the analyzer: PackAsAnalyzer.
The reason for that is that the additional metadata explains how the
reference works (no assembly output reference, added as an Analyzer
output item) vs. the AnalyzerReference which is a repo custom item
that doesn't tell you that behind the scenes it actually gets converted
to a ProjectReference with the same metadata as if you would declare
that yourself as a P2P.

To summarize the change:

1. Consume an analyzer

<!-- Before -->
<AnalyzerReference Include="..." />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" OutputItemType="Analyzer" />

2. Pack an analyzer and consume it

<!-- Before -->
<AnalyzerReference Include="..." Pack="true" />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" OutputItemType="Analyzer" PackAsAnalyzer="true" />

3. Pack an analyzer without consuming it

<!-- Before -->
<AnalyzerReference Include="..." Pack="true" ReferenceAnalyzer="false" />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" PackAsAnalyzer="true" />

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Issue Details

---

d3af492 made it possible to reference
and package an analyzer via the same msbuild item by setting custom
metadata.

While reviewing other places that could use the AnalyzerReference item,
I realized that using this custom item doesn't provide much value and
makes us different to rest of the stack / customers as we don't follow
our own documentation.

Instead, IMHO it makes much more sense to keep using a
ProjectReference item with the documented set of required metadata, to
reference an analyzer and just define an additional custom metadata to
support packaging the analyzer: PackAsAnalyzer.
The reason for that is that the additional metadata explains how the
reference works vs. the AnalyzerReference which is a repo custom item
that doesn't tell you that behind the scenes it actually gets converted
to a ProjectReference with the same metadata as if you would declare
that yourself as a P2P.

To summarize the change:

1. Consume an analyzer

<!-- Before -->
<AnalyzerReference Include="..." />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" OutputItemType="Analyzer" />

2. Pack an analyzer and consume it

<!-- Before -->
<AnalyzerReference Include="..." Pack="true" />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" OutputItemType="Analyzer" PackAsAnalyzer="true" />

3. Pack an analyzer without consuming it

<!-- Before -->
<AnalyzerReference Include="..." Pack="true" ReferenceAnalyzer="false" />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" PackAsAnalyzer="true" />

Author:	ViktorHofer
Assignees:	ViktorHofer
Labels:	area-Infrastructure-libraries
Milestone:	7.0.0

[eerhardt]

I'm not sure I am excited about this approach, since it creates a burden on all the projects that want to consume an analyzer.

<!-- Before -->
<AnalyzerReference Include="..." />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" OutputItemType="Analyzer" />

The "Before" is much cleaner, and easy to read/understand.

What if we supported 2 scenarios: 1 & 3 above. (I don't think 2 is a common scenario, or really will be used ever. But we will see.):

1. Consume an analyzer

<!-- Before -->
<AnalyzerReference Include="..." />
<!-- After -->
<AnalyzerReference Include="..." />

3. Pack an analyzer without consuming it

<!-- Before -->
<AnalyzerReference Include="..." Pack="true" ReferenceAnalyzer="false" />
<!-- After -->
<ProjectReference Include="..." ReferenceOutputAssembly="false" PackAsAnalyzer="true" />

UPDATE: Thinking more about this, how does a "normal dev" reference a local Analyzer they have in their repo in another project? Is it like you are proposing? <ProjectReference Include="..." ReferenceOutputAssembly="false" OutputItemType="Analyzer" /> ? If so, maybe that is the right way to go - that way we don't have special logic, and just do it like a "normal" .NET dev would.

[ericstj]

@ViktorHofer if this isn't going to be merged in 7.0 then it might be better to close for now.

[ViktorHofer]

Agreed, closing. I will bring this back later.