Saving an AdditionalFiles document in Balanced mode fails to trigger source generator

[AArnott]

Version Used: VS 17.12 (35114.17.main)

Steps to Reproduce:

0. Configure C# Advanced to (its default) "Balanced" source generator mode.
1. Create a new C# console project
2. Add a package reference to Microsoft.Windows.CsWin32
3. Create a NativeMethods.txt file and give it the content: GetTickCount
4. Open Program.cs and write code to consume it.
5. Reactivate the NativeMethods.txt file and clear the content.
6. Save the file.

Expected Behavior:

Saving the NativeMethods.txt file, per the wording of the Balanced source generator mode, should trigger source generation, causing an error in Program.cs.

Actual Behavior:

Saving the NativeMethods.txt does not trigger source generation. Switching to Program.cs and saving it (though it has no unsaved changes) is necessary for the source generator to run again.

Proposal

Saving files in the AdditionalFile item list should trigger source generation the same way that saving Compile items does.

[CyrusNajmabadi]

Yes. Def a bug.