Fix S4056: Rule should not recommend to use obsolete methods

[gkello]

Description

The usage of Enum.ToString() method is detected by S4056 rule, but the overloads which are using IFormatProvider are depreciated, as described in https://docs.microsoft.com/en-us/dotnet/api/system.enum.tostring?view=netframework-4.7

ToString(String, IFormatProvider) This method overload is obsolete; use ToString(String).
ToString(IFormatProvider) This method overload is obsolete; use ToString().

Repro steps

string str1 = DayOfWeek.Monday.ToString();
string str2 = DayOfWeek.Monday.ToString("F");

Expected behavior

No issues for S4056 is detected

Actual behavior

Both lines are generating

Warning S4056 Use the overload that takes a 'CultureInfo' or 'IFormatProvider' parameter.

Known workarounds

Related information

• SonarAnalyzer.CSharp 6.3.0.2862
• Visual Studio Professional 2017, version 15.3.1

[Evangelink]

Hi @gkello,

Thanks for the feedback. You are right this usage is deprecated since fwk 2.0, we will fix this soon.

• Update RSPEC-4056 to include exception
• Update rule to conform to new behavior.