cast_to_non_type

The name '{0}' isn't a type, so it can't be used in an 'as' expression.

The analyzer produces this diagnostic when the name following the as in a cast expression is defined to be something other than a type.

The following code produces this diagnostic because x is a variable, not a type:

num x = 0;
int y = x as x;

Replace the name with the name of a type:

num x = 0;
int y = x as int;