result code = -1
standard error = {
tests/diagnostics/setter-method.slang(16): note 30049: attempting to assign to a const variable or immutable member; use '[mutating]' attribute on the containing method to allow modification
tests/diagnostics/setter-method.slang(16): error 30011: left of '=' is not an l-value.
        center = value;
               ^
tests/diagnostics/setter-method.slang(21): note 30049: attempting to assign to a const variable or immutable member; use '[mutating]' attribute on the containing method to allow modification
tests/diagnostics/setter-method.slang(21): error 30011: left of '=' is not an l-value.
        this.radius = value;
                    ^
}
standard output = {
}