Debugging CoreFX build issues
========================================

## MSBuild debug options

* Enable MSBuild diagnostics log (msbuild.log):
`dotnet build my.csproj /flp:v=diag`
* Generate a flat project file (out.pp):
`dotnet build my.csproj /pp:out.pp`
* Generate a binary log usable by the [MSBuild Binary and Structured Log Viewer](http://msbuildlog.com/):
`dotnet build my.csproj /bl`

## Steps to debug packaging build issues

(This documentation is work in progress.)

I found the following process to help when investigating some of the build issues caused by incorrect packaging.

To quickly validate if a given project compiles on all supported configurations use `dotnet build /t:RebuildAll`. This applies for running tests as well. For more information, see [Building individual libraries](../../building/libraries/README.md#building-individual-libraries)

Assuming the current directory is `\src\contractname\`:

1. Build the `\ref` folder: `dotnet build`


Check the logs for output such as:
```
Project "S:\c1\src\System.Net.ServicePoint\ref\System.Net.ServicePoint.csproj" (1) is building "S:\c1\src\System.Net.ServicePoint\ref\System.Net.ServicePoint.csproj" (2:3) on node 1
(Build target(s)).

[...]

CopyFilesToOutputDirectory:
  Copying file from "S:\c1\bin/obj/ref/System.Net.ServicePoint/4.0.0.0/System.Net.ServicePoint.dll" to "S:\c1\bin/ref/System.Net.ServicePoint/4.0.0.0/System.Net.ServicePoint.dll".
  System.Net.ServicePoint -> S:\c1\bin\ref\System.Net.ServicePoint\4.0.0.0\System.Net.ServicePoint.dll
  Copying file from "S:\c1\bin/obj/ref/System.Net.ServicePoint/4.0.0.0/System.Net.ServicePoint.pdb" to "S:\c1\bin/ref/System.Net.ServicePoint/4.0.0.0/System.Net.ServicePoint.pdb".

[...]

Project "S:\c1\src\System.Net.ServicePoint\ref\System.Net.ServicePoint.csproj" (1) is building "S:\c1\src\System.Net.ServicePoint\ref\System.Net.ServicePoint.csproj" (2:4) on node 1
(Build target(s)).

[...]

CopyFilesToOutputDirectory:
  Copying file from "S:\c1\bin/obj/ref/System.Net.ServicePoint/4.0.0.0/netcoreapp1.1/System.Net.ServicePoint.dll" to "S:\c1\bin/ref/System.Net.ServicePoint/4.0.0.0/netcoreapp1.1/System.Net.ServicePoint.dll".
  System.Net.ServicePoint -> S:\c1\bin\ref\System.Net.ServicePoint\4.0.0.0\netcoreapp1.1\System.Net.ServicePoint.dll
  Copying file from "S:\c1\bin/obj/ref/System.Net.ServicePoint/4.0.0.0/netcoreapp1.1/System.Net.ServicePoint.pdb" to "S:\c1\bin/ref/System.Net.ServicePoint/4.0.0.0/netcoreapp1.1/System.Net.ServicePoint.pdb".
```

Using your favourite IL disassembler, ensure that each platform contains the correct APIs. Missing APIs from the contracts is likely caused by not having the right `DefineConstants` tags in the csproj files.

2. Build the `\src` folder: `dotnet build`

Use the same technique above to ensure that the binaries include the correct implementations.

3. Build the `\pkg` folder: `dotnet build`

Ensure that all Build Pivots are actually being built. This should build all .\ref and .\src variations as well as actually creating the NuGet packages.

Verify that the contents of the nuspec as well as the actual package is correct. You can find the packages by searching for the following pattern in the msbuild output:

```
GetPkgProjPackageDependencies:
Skipping target "GetPkgProjPackageDependencies" because it has no inputs.
CreatePackage:
  Created 'S:\c1\bin/packages/Debug/System.Net.Security.4.4.0-beta-24625-0.nupkg'
  Created 'S:\c1\bin/packages/Debug/symbols/System.Net.Security.4.4.0-beta-24625-0.symbols.nupkg'
Build:
  System.Net.Security -> S:\c1\bin/packages/Debug/specs/System.Net.Security.nuspec
```

To validate the content of the nupkg, change the extension to .zip. As before, use an IL disassembler to verify that the right APIs are present within `ref\<platform>\contractname.dll` and the right implementations within the `lib\<platform>\contractname.dll`.

4. Run the tests from `\tests`: `dotnet build /t:test`

Ensure that the test is referencing the correct pkg. For example:
```
  <ItemGroup>
    <ProjectReference Include="..\pkg\System.Net.ServicePoint.pkgproj" />
  </ItemGroup>
```

Ensure that the right `BuildTargetFramework` (what we're testing) is set.

To identify which of the combinations failed, search for the following pattern in the output:

```
Project "S:\c1\src\System.Net.ServicePoint\tests\System.Net.ServicePoint.Tests.csproj" (1) is building "S:\c1\src\System.Net.ServicePoint\tests\System.Net.ServicePoint.Tests.csproj"
(2:5) on node 1 (Build target(s)).
ResolvePkgProjReferences:
  Resolved compile assets from .NETStandard,Version=v2.0: S:\c1\bin\ref\System.Net.ServicePoint\4.0.0.0\System.Net.ServicePoint.dll
  Resolved runtime assets from .NETCoreApp,Version=v2.0: S:\c1\bin\AnyOS.AnyCPU.Debug\System.Net.ServicePoint\System.Net.ServicePoint.dll
```

To run a test from a single Build Pivot combination, specify all properties and build the `csproj`:

```
dotnet build System.Net.ServicePoint.Tests.csproj -f netcoreapp2.0 /t:test /p:OuterLoop=true /p:xunitoptions=-showprogress
```
Will run the test using the following pivot values:
* Architecture: AnyCPU
* Flavor: Debug
* OS: Windows_NT
* Target: netstandard2.0