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Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
Most developers expect property access to be as efficient as field access. However, if a property returns a copy of an array or collection, it will
be much slower than a simple field access, contrary to the caller’s likely expectations. Therefore, such properties should be refactored into methods
so that callers are not surprised by the unexpectedly poor performance.
This rule tracks calls to the following methods inside properties:

   Enumerable.ToList 
   Enumerable.ToArray 
   Array.Clone 

How to fix it
Code examples
Noncompliant code example
private List<string> foo = new List<string> { "a", "b", "c" };
private string[] bar = new string[] { "a", "b", "c" };

public IEnumerable<string> Foo => foo.ToList(); // Noncompliant: collection foo is copied

public IEnumerable<string> Bar => (string[])bar.Clone(); // Noncompliant: array bar is copied

Compliant solution
private List<string> foo = new List<string> { "a", "b", "c" };
private string[] bar = new string[] { "a", "b", "c" };

public IEnumerable<string> GetFoo() => foo.ToList();

public IEnumerable<string> GetBar() => (string[])bar.Clone();

Resources
Documentation

   Properties (C# Programming
  Guide) 
   Fields (C# Programming Guide) 
   Collections (C#) 
   Enumerable.ToList 
   Enumerable.ToArray 
   Array.Clone