Compiler Error CS0136

A local variable named 'var' cannot be declared in this scope because it would give a different meaning to 'var', which is already used in a 'parent or current/child' scope to denote something else

A variable declaration hides another declaration that would otherwise be in scope. Rename the variable that is declared on the line that generated CS0136.

Example

The following sample generates CS0136:

// CS0136.cs
namespace MyNamespace
{
   public class MyClass
   {
      public static void Main()
      {
         int i = 0;
         {
            char i = 'a';   // CS0136, hides int i
         }
         i++;
      }
   }
}

From the C# Language Specification, Section 7.5.2.1:

For each occurrence of a given identifier as a simple-name in an expression or declarator, within the local variable declaration space (§3.3) immediately enclosing that occurrence, every other occurrence of the same identifier as a simple-name in an expression or declarator must refer to the same entity. This rule ensures that the meaning of a name is always the same within a given block, switch block, for-, foreach- or using-statement, or anonymous function.