Code inspection: Lambda expression/anonymous method must be 'static' to avoid allocations

This inspection reports a capture-free lambda expression passed where the delegate is required to be explicitly static, for example to a parameter marked with [RequireStaticDelegate].

Example

                void M([RequireStaticDelegate] Func<int, int> f) {}
                void Test()
                {
                    M(x => x + 1);
                }
            

                void M([RequireStaticDelegate] Func<int, int> f) {}
                void Test()
                {
                    M(static x => x + 1);
                }
            

Quick-fix

Add the static modifier to the lambda expression.

30 March 2026