CA2223: Members should differ by more than return type







Breaking Change



Two public or protected members have signatures that are identical except for return type.

Rule Description

Although the common language runtime permits the use of return types to differentiate between otherwise identical members, this feature is not in the Common Language Specification, nor is it a common feature of .NET programming languages. When members differ only by return type, developers and development tools might not correctly distinguish between them.

How to Fix Violations

To fix a violation of this rule, change the design of the members so that they are unique based only on their names and parameter types, or do not expose the members.

When to Suppress Warnings

Do not suppress a warning from this rule.


The following example, in Microsoft intermediate language (MSIL), shows a type that violates this rule. Notice that this rule cannot be violated by using C# or Visual BasicĀ .NET.

.namespace UsageLibrary
  .class public auto ansi beforefieldinit ReturnTypeTest
         extends [mscorlib]System.Object
    .method public hidebysig instance int32
            AMethod(int32 x) cil managed
      // Code size       6 (0x6)
      .maxstack  1
      .locals init (int32 V_0)
      IL_0000:  ldc.i4.0
      IL_0001:  stloc.0
      IL_0002:  br.s       IL_0004

      IL_0004:  ldloc.0
      IL_0005:  ret
    } // end of method ReturnTypeTest::AMethod

    .method public hidebysig instance string
            AMethod(int32 x) cil managed
      // Code size       10 (0xa)
      .maxstack  1
      .locals init (string V_0)
      IL_0000:  ldstr      "test"
      IL_0005:  stloc.0
      IL_0006:  br.s       IL_0008

      IL_0008:  ldloc.0
      IL_0009:  ret
    } // end of method ReturnTypeTest::AMethod

    .method public hidebysig specialname rtspecialname
            instance void  .ctor() cil managed
      // Code size       7 (0x7)
      .maxstack  1
      IL_0000:  ldarg.0
      IL_0001:  call       instance void [mscorlib]System.Object::.ctor()
      IL_0006:  ret
    } // end of method ReturnTypeTest::.ctor

  } // end of class ReturnTypeTest

} // end of namespace UsageLibrary