ab6d0f08b7
## Review A dedicated reviewer checked the rule description successfully for: - [ ] logical errors and incorrect information - [ ] information gaps and missing content - [ ] text style and tone - [ ] PR summary and labels follow [the guidelines](https://github.com/SonarSource/rspec/#to-modify-an-existing-rule)
116 lines
3.3 KiB
Plaintext
116 lines
3.3 KiB
Plaintext
include::../introduction.adoc[]
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include::../why-is-this-an-issue.adoc[]
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include::../what-is-the-potential-impact.adoc[]
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This rule looks for operands of a boolean expression never changing the result of the expression. It also applies to the https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/null-conditional-operators[null conditional operator] when one of the operands always evaluates to `Nothing`.
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[source,vbnet]
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----
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Dim d As String = Nothing
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Dim v1 = If(d, "value")
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----
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=== Exceptions
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This rule will not raise an issue in either of these cases:
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* When the condition is a single `Const bool`
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[source,vbnet]
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----
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Const debug = False
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'...
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If debug Then
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' Print something
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End If
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----
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* When the condition is the literal `True` or `False`.
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In these cases, it is obvious the code is as intended.
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include::../how-to-fix-it.adoc[]
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=== Code examples
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==== Noncompliant code example
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[source,vbnet,diff-id=1,diff-type=noncompliant]
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----
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Public Sub Sample(ByVal b As Boolean, ByVal c As Boolean)
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Dim a = True
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If a Then ' Noncompliant: "a" is always "true"
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DoSomething()
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End If
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If b AndAlso a Then ' Noncompliant: "a" is always "true"
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DoSomething()
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End If
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If c OrElse Not a Then ' Noncompliant: "Not a" is always "false"
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DoSomething()
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End If
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Dim d As String = Nothing
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Dim v1 = If(d, "value") ' Noncompliant: "d" is always Nothing and v1 is always "value".
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Dim v2 = If(s, d) ' Noncompliant: "d" is always Nothing and v2 is always equal to s.
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End Sub
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----
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==== Compliant solution
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[source,vbnet,diff-id=1,diff-type=compliant]
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----
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Public Sub Sample(ByVal b As Boolean, ByVal c As Boolean, ByVal s As String)
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Dim a = IsAllowed()
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If a Then ' Compliant
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DoSomething()
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End If
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If b AndAlso a Then ' Compliant
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DoSomething()
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End If
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If c OrElse Not a Then ' Compliant
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DoSomething()
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End If
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Dim d As String = GetStringData()
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Dim v1 = If(d, "value") ' Compliant
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Dim v2 = If(s, d) ' Compliant
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End Sub
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----
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== Resources
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=== Documentation
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* https://cwe.mitre.org/data/definitions/571[MITRE, CWE-571] - Expression is Always True
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* https://cwe.mitre.org/data/definitions/570[MITRE, CWE-570] - Expression is Always False
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* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/operators-and-expressions/logical-and-bitwise-operators[Logical and Bitwise Operators in Visual Basic]
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* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/null-conditional-operators[?. and ?() null-conditional operators (Visual Basic)]
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* Microsoft Learn - https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/null-conditional-operators[If operator called with two arguments]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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* Change this condition so that it does not always evaluate to "[true|false]".
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* Change this expression which always evaluates to the same result.
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include::../highlighting.adoc[]
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'''
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== Comments And Links
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(visible only on this page)
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include::../comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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