Fix S3900 FP: Recognize VB extensions

[pavel-mikula-sonarsource]

Follow up of #6797

This is a draft, rebase will be needed. Squash S3900-VB commit doesn't need a review, it's in #7045

[antonioaversa]

Mostly doubts on the behavior of the rule, by looking at the ITs.

The review took a while due to the fact that a lot of changes appearing in this PR actually belong to another PR (#7045), which is also in the review phase, and the related commit (Squash S3900-VB) had to be taken out from the diff, while reviewing.

I think it would have been easier for this PR to target the branch of #7045, rather than master. This way there would have not been the need of squashing 7045 content into a single commit and asking for the review of the difference, since the full PR diff (and the Changes tab on GitHub) would have reflected the actual content of this PR.

Concerning ITs: it was difficult to only review the difference between the JSON files, as they appear in 7045, and the JSON as they appear here, so I went through all of them in this PR anyway. Most likely some comments will apply to 7045 instead.

[antonioaversa]

I am a bit confused by how S3900 is working here.

This corresponds to the line:

sFormula.Replace("(", String.Empty).Length = sFormula.Replace(")", String.Empty).Length

Do you know why only the first sFormula dereference is detected, and not the second, yet the third is (line 169)?

[pavel-mikula-sonarsource]

The = is a comparison operator. It learns NotNull from evaluating the left operand, and by the time it evaluates the right one, it already knows NotNull.
This seems fine to me.

[antonioaversa]

Yes, the rule not reporting on the right side of the comparison, after having learnt NotNull on the left side, is fine to me too. What still confuses me is line 169:

If sFormula.Replace("(", String.Empty).Length = sFormula.Replace(")", String.Empty).Length Then
    'step 2: all code between brackets
    For Each mReg In Regex.Matches(sFormula, "\((.+)\)")
        rResult = EvaluateFormula(mReg.Groups(1).ToString())
        sFormula = sFormula.Replace(mReg.ToString(), rResult.ToString("0.00"))   ' Line 169
    Next

Inside the If, sFormula has ObjectConstraint.NotNull, and it seems to me that there is nothing that should make the engine forget about such constraint. Is it linked to the fact that the loop is executed twice, and sFormula is assigned the result of sFormula.Replace, making sFormula unknown at the second iteration?

[pavel-mikula-sonarsource]

Yes, exactly.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[antonioaversa]

LGTM
Thanks for the clarification, now the functionality is much more clear to me!
One doubt left: #7047 (comment)