Documents node in embedded PDB different in .NET Core 3

[daveaglick]

This intrigued me and I've been meaning to dig into how SourceLink works anyway, so here we are. I think I know what's going on...or at least why it's failing. I just don't know how to fix it.

For starters, here's the embedded PDB metadata of a build on .NET Core SDK 2.2.401:

And here's the embedded PDB metadata of a build on .NET Core SDK 3.1.101:

There's so much more! But most importantly, check out that "Documents" node. It doesn't even exist in the .NET Core 2.2 build.

This can be verified by the sourcelink tool - here it is listing documents for the 2.2.401 build:

>tools\sourcelink print-documents bin\Release\netstandard2.0\dotnetcore-sourcelink-test-bug.dll

>

Well that was anticlimactic. Here it is for the 3.1.101 build:

>dotnet sourcelink print-documents bin\Release\netstandard2.0\dotnetcore-sourcelink-test-bug.dll
8c4deb227a4346af8cf4e320a3d78efdce7dd602bc423d79cd2d448dbb9ffc41 sha256 csharp C:\Code\Experiments\dotnetcore-sourcelink-test-bug\Class1.cs
a529e7a12beb0f9db49ac28387cf2d33b2dc765f7d70b604834a085118757966 sha256 csharp C:\Code\Experiments\dotnetcore-sourcelink-test-bug\obj\Release\netstandard2.0\dotnetcore-sourcelink-test-bug.AssemblyInfo.cs
a6e03ae4df13fe05345e9022d1f1cd24ecae4bfd66db4843697c855d9f9335f4 sha256 csharp C:\Users\dglick\AppData\Local\Temp\.NETStandard,Version=v2.0.AssemblyAttributes.cs

>

I'm pretty sure that confirms the sourcelink tool is using the Documents node in the PDB. Just to be sure, I peeped the sourcelink tool code (which isn't in the DNF repo, but in a repo from @ctaggart directly):

Here's the actual code for the test command: https://github.com/ctaggart/SourceLink/blob/be8dcdaad09a2891bc0e1d04e43af40a1e482158/dotnet-sourcelink/Program.cs#L203

If we go back and look more closely at the output from test when it fails:

>dotnet sourcelink test bin\Release\dotnetcore-sourcelink-test-bug.1.0.0.nupkg
1 Documents without URLs:
a6e03ae4df13fe05345e9022d1f1cd24ecae4bfd66db4843697c855d9f9335f4 sha256 csharp C:\Users\dglick\AppData\Local\Temp\.NETStandard,Version=v2.0.AssemblyAttributes.cs
1 Documents with errors:
a529e7a12beb0f9db49ac28387cf2d33b2dc765f7d70b604834a085118757966 sha256 csharp C:\Code\Experiments\dotnetcore-sourcelink-test-bug\obj\Release\netstandard2.0\dotnetcore-sourcelink-test-bug.AssemblyInfo.cs
https://raw.githubusercontent.com/shiftkey/dotnetcore-sourcelink-test-bug/e707de6428305d6a2bd997a516b5444592421cfd/obj/Release/netstandard2.0/dotnetcore-sourcelink-test-bug.AssemblyInfo.cs
error: url failed NotFound: Not Found
sourcelink test failed
failed for lib/netstandard2.0/dotnetcore-sourcelink-test-bug.dll
1 files did not pass in bin\Release\dotnetcore-sourcelink-test-bug.1.0.0.nupkg

We can see two errors which make sense to me now because we can track them back to entries in the PDB metadata as document nodes:

• The file at "C:\Users\dglick\AppData\Local\Temp.NETStandard,Version=v2.0.AssemblyAttributes.cs" doesn't exist - that makes sense given that the file isn't local
• The file with a translated URL of "https://raw.githubusercontent.com/shiftkey/dotnetcore-sourcelink-test-bug/e707de6428305d6a2bd997a516b5444592421cfd/obj/Release/netstandard2.0/dotnetcore-sourcelink-test-bug.AssemblyInfo.cs" can't be found - again makes sense given that it translated a build-time generated file to a GitHub URL and the generated file obviously isn't committed.

TL;DR:

• Lots of extra PDF metadata is getting added when using the .NET Core SDK 3.1.101
• This extra metadata includes document nodes for generated files
• The sourcelink tool reads those nodes from the embedded PDB and has no idea they're not actual source files

I'm left with the following questions:

• Why is the 3.1.101 SDK generating these document nodes in the embedded PDB but earlier SDKs are not
• Are the document nodes "correct" in the sense that not generating them was actually the wrong behavior?
• Does the sourcelink tool need to know how to identify and deal with (or ignore) generated AssemblyAttributes.cs, AssemblyInfo.cs, and other generated source files?

[shiftkey]

@daveaglick thanks for digging into this and pointing out the interesting changes that might be important here. I'm gonna let this sit for a few days and let others chime in about ways to address this.

[daveaglick]

@shiftkey No problem at all - was a nice distraction from the usual even if it's not particularly helpful as a root cause analysis. Looks like @ctaggart has picked it up and has some ideas about what's going on.

[rainersigwald]

Looks like a change in the compiler. I can pass the test using .NET Core SDK 3.1.200-preview-014883 (what I had handy, should be identical to 3.1.1xx in this respect) with this patch:

diff --git a/dotnetcore-sourcelink-test-bug.csproj b/dotnetcore-sourcelink-test-bug.csproj
index f4f552a..5634149 100644
--- a/dotnetcore-sourcelink-test-bug.csproj
+++ b/dotnetcore-sourcelink-test-bug.csproj
@@ -7,6 +7,10 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Net.Compilers" Version="3.3.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
   </ItemGroup>
 

All that does is force using an older C# compiler. Maybe the new one has different behavior with respect to generated files?

[poke]

should be identical to 3.1.1xx in this respect

Can confirm that. I was able to get it work with your patch on 3.1.1.

[japj]

@daveaglick related to untracked sources: there is an option to embed untracked sources in the pdb as described at https://github.com/dotnet/sourcelink/blob/master/docs/README.md#embeduntrackedsources

That will allow the debugger to also debug "into" sources that are not in version control (e.g. build time generated code).

[shiftkey]

@rainersigwald @poke is there a way to validate that for non-Windows usage? I tried the same but it errors on macOS and it fails to build while mentioning Win32Exception (lol)

$ git diff
diff --git a/dotnetcore-sourcelink-test-bug.csproj b/dotnetcore-sourcelink-test-bug.csproj
index f4f552a..c52f4f6 100644
--- a/dotnetcore-sourcelink-test-bug.csproj
+++ b/dotnetcore-sourcelink-test-bug.csproj
@@ -7,6 +7,10 @@
   </PropertyGroup>

   <ItemGroup>
+    <PackageReference Include="Microsoft.Net.Compilers" Version="3.4.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
   </ItemGroup>

$ ./repro.sh
Tool 'sourcelink' (version '3.1.1') was restored. Available commands: sourcelink

Restore was successful.
Microsoft (R) Build Engine version 16.4.0+e901037fe for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 27.43 ms for /Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj.
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error MSB3883: Unexpected exception:  [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error : System.ComponentModel.Win32Exception (8): Exec format error [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at System.Diagnostics.Process.ForkAndExecProcess(String filename, String[] argv, String[] envp, String cwd, Boolean redirectStdin, Boolean redirectStdout, Boolean redirectStderr, Boolean setCredentials, UInt32 userId, UInt32 groupId, UInt32[] groups, Int32& stdinFd, Int32& stdoutFd, Int32& stderrFd, Boolean usesTerminal, Boolean throwOnNoExec) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at System.Diagnostics.Process.StartCore(ProcessStartInfo startInfo) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at System.Diagnostics.Process.Start() [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at Microsoft.Build.Utilities.ToolTask.ExecuteTool(String pathToTool, String responseFileCommands, String commandLineCommands) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.4.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at Microsoft.CodeAnalysis.BuildTasks.ManagedCompiler.ExecuteTool(String pathToTool, String responseFileCommands, String commandLineCommands) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
file does not exist: bin/Release/dotnetcore-sourcelink-test-bug.1.0.0.nupkg

[daveaglick]

@japj Cool, TIL

Confirmed that setting <EmbedUntrackedSources>true</EmbedUntrackedSources> gets past the "1 Documents without URLs" due to missing AssemblyAttributes.cs but doesn't resolve the "1 Documents with errors" error from AssemblyInfo.cs.

Also doesn't address the underlying problem of compiler/sourcelink compatibility regarding compiler generated files and embedded PDBs, but at least gets closer to a successful sourcelink test.

[poke]

@shiftkey Could you try the 3.3.0 compiler version? 3.4.0 also didn’t work for me on Windows due to some MSBuild version.

[shiftkey]

@poke same issue on macOS

./repro.sh
Tool 'sourcelink' (version '3.1.1') was restored. Available commands: sourcelink

Restore was successful.
Microsoft (R) Build Engine version 16.4.0+e901037fe for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 182.35 ms for /Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj.
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error MSB3883: Unexpected exception:  [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error : System.ComponentModel.Win32Exception (8): Exec format error [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at System.Diagnostics.Process.ForkAndExecProcess(String filename, String[] argv, String[] envp, String cwd, Boolean redirectStdin, Boolean redirectStdout, Boolean redirectStderr, Boolean setCredentials, UInt32 userId, UInt32 groupId, UInt32[] groups, Int32& stdinFd, Int32& stdoutFd, Int32& stderrFd, Boolean usesTerminal, Boolean throwOnNoExec) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at System.Diagnostics.Process.StartCore(ProcessStartInfo startInfo) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at System.Diagnostics.Process.Start() [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at Microsoft.Build.Utilities.ToolTask.ExecuteTool(String pathToTool, String responseFileCommands, String commandLineCommands) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
/Users/shiftkey/.nuget/packages/microsoft.net.compilers/3.3.0/tools/Microsoft.CSharp.Core.targets(59,5): error : at Microsoft.CodeAnalysis.BuildTasks.ManagedCompiler.ExecuteTool(String pathToTool, String responseFileCommands, String commandLineCommands) [/Users/shiftkey/src/dotnetcore-sourcelink-test-bug/dotnetcore-sourcelink-test-bug.csproj]
file does not exist: bin/Release/dotnetcore-sourcelink-test-bug.1.0.0.nupkg

[shiftkey]

@poke @rainersigwald nevermind, I should have spotted this clue from NuGet:

This package can be used to compile code targeting any platform, but can only be run using the desktop .NET 4.7.2+ Full Framework.

I'll dust off my Windows VM

[KirillOsenkov]

Paging @tmat

[tmat]

Can you share the binaries?