VB compiler incorrectly parses paths in /embed switch containing ,

[tmat]

Both
vbc /debug:portable program.vb /embed:a,b.vb and
vbc /debug:portable program.vb /embed:"a,b.vb"

result in errors:

vbc : error BC2001: file 'C:\Temp\a' could not be found
vbc : error BC2001: file 'C:\Temp\b.vb' could not be found

This issue is not limited to command line. The problem is also with vbc task:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <RootNamespace>vb</RootNamespace>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <EmbeddedFiles Include="a,b.vb" />
  </ItemGroup>
</Project>

This is a problem since .NET SDK uses comma in generated file name:
.NETStandard,Version=v2.0.AssemblyAttributes.vb

[jaredpar]

What is the expected behavior here?

[tmat]

Not treat , as a path separator.

[AArnott]

See also #31611 which talks about the Sources input specifically. So this problem is shared across both inputs.

[AArnott]

OK, so that one was a dupe of this.

But this issue is becoming more important IMO because of the recommendation to embed untracked source files in the portable PDB. I can get a new VB project to repro the failure just by adding two lines:

 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <RootNamespace>b</RootNamespace>
     <TargetFramework>netcoreapp2.2</TargetFramework>
+     <EmbedUntrackedSources>true</EmbedUntrackedSources>
   </PropertyGroup>

   <ItemGroup>
+     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0-beta-63127-02" PrivateAssets="All" />
   </ItemGroup>

 </Project>