Improve S1125: Flexibility in opting in and out constant patterns

[antonioaversa]

The context

After this issue, reported in 2019, was implemented earlier this year, we have got a user request to relax the reporting in presence of constant patterns: https://github.com/SonarSource/sonar-dotnet/issues/8147.

The goal

Provide the user with more flexibility, by allowing to opt in and out:

• ==-based comparisons: == true and == false
• is false comparison
• is true comparison

Possible solutions

From @antonioaversa I think we have four options here:

1. keep the rule as is, and reject the user request: b is false and b is true remain redundant

Or split the rule into two: take out is cases from 1125 and create a new rule for them: 2. with the new rule treating b is true as redundant and b is false as redundant 3. with the new rule treating b is true as redundant and b is false as valid

4. Or keep b is true in S1125 and have the new rule only report on b is false.

From @Tim-Pohlmann

There could be three rules:

1. Use x instead of x == true and x is true.
2. Use !x instead of x == false and x is false.
3. Use x is true/false instead of x == true/false.

Allowed patterns based on enabled rules:

• Only 1: x !x x == false x is false
• 1 + 2: x !x
• Only 3: x !x x is true x is false
• 1 + 3: x !x x is false

In addition to that 3 could also have an effect on != or that could be a separate thing.