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Compiler Error CS0430

The extern alias 'alias' was not specified in a /reference option

This error occurs when extern Alias is encountered but Alias was not specified as a reference on the command line. To resolve CS0430, compile with /reference.

// CS0430_a.cs
// compile with: /target:library 
public class MyClass {}

Compiling with /reference:MyType=cs0430_a.dll to refer to the DLL created in the previous sample resolves this error. The following sample generates CS0430.

// CS0430_b.cs
extern alias MyType;   // CS0430
public class Test 
   public static void Main() {}