Massive dynamic issues

gistfile1.cs

// Example 1: 
// conn has a compile time type of DbConnection, as this is what is returned by OpenConnection
// cmd has compile time type of DbCommand, as this is what is returned by CreateCommand
// Both have runtime types of the more specific SqlConnection/SqlCommand
public static dynamic DynamicWeirdness() {
	using (var conn = OpenConnection()) {
		var cmd = CreateCommand("SELECT * FROM Products");
		cmd.Connection = conn;
	}
	Console.WriteLine("It worked!");
	Console.Read();
	return null;
}

// Example 2:
// conn has a compile time type of DbConnection, as this is what is returned by OpenConnection
// cmd is only evaluated at runtime due to dynamic. At runtime, it becomes the most specific SqlCommand
// SqlCommand.Connection requires SqlConnection and although conn's runtime type is SqlConnection, its
// compile-time is still DbConnection and thus you get the error
public static dynamic DynamicWeirdness() {
	dynamic ex = new ExpandoObject();
	ex.TableName = "Products";
	using (var conn = OpenConnection()) {
		var cmd = CreateCommand(ex);
		cmd.Connection = conn;
	}
	Console.WriteLine("It worked!");
	Console.Read();
	return null;
}

// Example 3:
// conn has a compile time type of DbConnection, as this is what is returned by OpenConnection
// cmd is evaluated at runtime due to dynamic to be any type compatible with DbCommand.
// Runtime type is still SqlCommand, but compile-time is specified as DbCommand (due to not using var).
// DbCommand.Connection accepts DbConnection, which is the compile-time type of conn
public static dynamic DynamicWeirdness() {
    dynamic ex = new ExpandoObject ();
    ex.Query = "SELECT * FROM Products";
    using (var conn = OpenConnection()) {
        DbCommand cmd = CreateCommand(ex); // <-- DON'T USE VAR
        cmd.Connection = conn;
    }
    Console.WriteLine("It worked!");
    Console.Read();
    return null;
}

OK so the next twist is that if I set "using dynamic conn = OpenConnection()" it works as well. What I mean by "the entire block is an expression" means exactly that - if you hover over it the compiler has no idea what's going on - there's "too much dynamic" happening. So it hands it off to the runtime binder to figure out.

Now here's where it gets interesting. Take a look at the question again - see the last edit? See where I output the runtime types for each variable? They're SqlClient.

We're talking in circles here - but everything you're writing here is not convincing me that there's a compile-time type for the code I've written. There can't be. It's dynamic and maybe IL is taking a swing at figuring it out... but there's no way that you and I can know what that special magic is since we're not compilers.