[Mono-dev] Empty IEnumerable Implementation Crashes C# Compiler

[shmuelie]

I needed to create a quick and dirty IEnumerable that that had no elements.
To do so I used the following code:

IEnumerator IEnumerable.GetEnumerator ()
{
	while(false)
	{
		yield return string.Empty;
	}
}

It compiled and work in .NET 4.0 but when I tried to use the same code in
Mono 4.0 I got the following crash report from the compiler:

Unhandled Exception: Mono.CSharp.InternalErrorException:
/.../MyClass.cs(16,17): <IEnumerable.GetEnumerator>c__Iterator0 --->
System.ArgumentException: Label not marked
  at System.Reflection.Emit.ILGenerator.label_fixup () [0x00000] in
<filename unknown>:0 
  at System.Reflection.Emit.MethodBuilder.fixup () [0x00000] in <filename
unknown>:0 
  at System.Reflection.Emit.TypeBuilder.CreateType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.TypeContainer.CloseType () [0x00000] in <filename
unknown>:0 
  --- End of inner exception stack trace ---
  at Mono.CSharp.TypeContainer.CloseType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.TypeContainer.CloseType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.ModuleContainer.CloseType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.Driver.Compile () [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Driver.Main (System.String[] args) [0x00000] in <filename
unknown>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: Mono.CSharp.InternalErrorException:
/Users/shmuelienglard/Projects/Learn/DummyEnumeratorCrash/MyClass.cs(16,17):
<IEnumerable.GetEnumerator>c__Iterator0 ---> System.ArgumentException: Label
not marked
  at System.Reflection.Emit.ILGenerator.label_fixup () [0x00000] in
<filename unknown>:0 
  at System.Reflection.Emit.MethodBuilder.fixup () [0x00000] in <filename
unknown>:0 
  at System.Reflection.Emit.TypeBuilder.CreateType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.TypeContainer.CloseType () [0x00000] in <filename
unknown>:0 
  --- End of inner exception stack trace ---
  at Mono.CSharp.TypeContainer.CloseType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.TypeContainer.CloseType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.ModuleContainer.CloseType () [0x00000] in <filename
unknown>:0 
  at Mono.CSharp.Driver.Compile () [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Driver.Main (System.String[] args) [0x00000] in <filename
unknown>:0 



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