Trailing period in vs-threading.MembersRequiringMainThread.txt causes compiler hang

[AArnott]

Bug description

The compiler entered a CPU intensive hang due to the ReadTypesAndMembers method in the vs-threading analyzers.

Repro steps

Add the content below to a file named vs-threading.MembersRequiringMainThread.txt that is supplied as an "AdditionalFile" to the compiler while the vs-threading analyzers are running on a project. Note the trailing period on the last line.

![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerBootstrapper]
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![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerBootstrapper3]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerBootstrapper4]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerBootstrapper5]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerBootstrapper6]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerProjectDeploy]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerProjectDeploy2]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerProjectDeployOperation]
![Microsoft.VisualStudio.Shell.Interop.IVsAppContainerProjectDeployResult]
![Microsoft.VisualStudio.Shell.Interop.IVsImmersiveProjectDeployTest]
![Microsoft.VisualStudio.Shell.Interop.SVsAppContainerProjectDeploy].

Expected behavior

The compiler completes. Maybe emits an error.

Actual behavior

The compiler hangs.

• Version used: 16.0.106

Additional context

@srdjanjovcic reported.