Code Inspection: The given expression of 'is' operator is always of the provided type
Last modified: 08 March 2021tip
In a compatibility check expr is type
between reference types, expr
on the left might be of a type assignable to type
on the right.
According to the C# documentation, "The is statement is true if expr is non-null and the object that results from evaluating the expression can be converted to type; otherwise, it returns false."
In other words, the only case when this check might evaluate to false
is when expr
is null
.
To reveal the actual semantics of the check in this case, we should replace the is
check with as simple null check.
This warning is similar to the compiler warning CS0183: The given expression is always of the provided ('type') type (which ReSharper also detects), but it deals with reference types, while the compiler warning occurs when there is conversion of value types.