Improve S3655: Support C# 9 and C# 10 syntax

[pavel-mikula-sonarsource]

Improve precision and detection of S3655 by migrating it to the new SE engine. While keeping the old implementation for Roslyn v1.x and v2.x series.

PRs:

• Clone TestCases from Sonar directory to Roslyn. Mark all Noncompliant as FIXME Non-compliant
• Create a dummy without implementation, register it in SymbolicExecutionRunner, add test methods
• Implement ShouldExecute
• Implement the rule - this depends on the engine capabilities
• ...investigate and fix whatever is missing
• Remove remaining FIXME annotations, close FP repro issues as fixed in this sprint

[pavel-mikula-sonarsource]

The idea is, that nullable symbol will share constraints with it's value. So the nullable itself will have Null or NotNull constraint. You can implement the rule based on this.

The rule will need a special handling for members like .HasValue and .GetValueOrDefault() that should not raise an issue when accessed.

[antonioaversa]

The rule will need a special handling for members like .HasValue and .GetValueOrDefault() that should not raise an issue when accessed.

I would rather say that Value should be the only one raising an issue when accessed. Every other method (e.g.ToString, GetHashCode, GetType, ...) on a Nullable<T> doesn't seem to raise an exception, no matter what's the value of the nullable.

[pavel-mikula-sonarsource]

The rule will need a special handling for members like .HasValue and .GetValueOrDefault() that should not raise an issue when accessed.

I would rather say that Value should be the only one raising an issue when accessed. Every other method (e.g.ToString, GetHashCode, GetType, ...) on a Nullable<T> doesn't seem to raise an exception, no matter what's the value of the nullable.

Yes, it's actually S2259 that needs special handling. And that one is extracted to #6840

[antonioaversa]

New issues, documenting behaviors detected during peach validation:

• S3655: Add repro for null conditional operator, null coalescing assignment, value tuples #7029, documenting FP and FN on ?., ??= and value tuples
• S3655: Document comparisons #7033, documenting FP and FN on lifted comparisons on nullable

[martin-strecker-sonarsource]

Closed as completed.