S3877 — Exceptions should not be thrown from unexpected methods

Why is this an issue?

The rule is reporting when an exception is thrown from certain methods and constructors. These methods are expected to behave in a specific way and throwing an exception from them can lead to unexpected behavior and break the calling code.

public override string ToString()
{
  if (string.IsNullOrEmpty(Name))
  {
    throw new ArgumentException(nameof(Name));  // Noncompliant
  }
  //...
}

An issue is raised when an exception is thrown from any of the following:

• ToString
• Object.Equals
• IEquatable.Equals
• GetHashCode
• IDisposable.Dispose
• Event accessors
• static constructors
• Module initializer attribute
• https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/operator-overloading
• implicit cast operators

Exceptions

Certain exceptions will be ignored in specific contexts, thus not raising the issue:

• System.NotImplementedException and its derivatives are ignored for all the aforementioned.
• System.InvalidOperationException, System.NotSupportedException, and System.ArgumentException and their derivatives are ignored in event accessors.

Resources

Documentation

• Exceptions and Exception Handling
• Best practices for exceptions
• CA1065: Do not raise exceptions in unexpected locations