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Fix Double-to-Long overflow check #73016

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merged 2 commits into from
May 9, 2024
Merged

Fix Double-to-Long overflow check #73016

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f28836e
Fix Double-to-Long overflow check
MichaelJLiu May 5, 2024
da07b53
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MichaelJLiu May 9, 2024
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2 changes: 1 addition & 1 deletion src/Compilers/VisualBasic/Portable/Semantics/CompileTimeCalculations.vb
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Original file line number Diff line number Diff line change
Expand Up @@ -603,7 +603,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
If sourceValue > &H7000000000000000L Then
Dim temporary As Double = (sourceValue - &H7000000000000000L)

If temporary < &H7000000000000000L AndAlso UncheckedCLng(temporary) > &H1000000000000000L Then
If temporary < &H7000000000000000L AndAlso UncheckedCLng(temporary) < &H1000000000000000L Then
Return False
End If
Else
Expand Down
47 changes: 45 additions & 2 deletions src/Compilers/VisualBasic/Test/Semantic/Semantics/Conversions.vb
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Expand Up @@ -605,7 +605,8 @@ End Class
New TypeAndValue(uint64Type, CULng(18)),
New TypeAndValue(decimalType, CDec(-11.3)),
New TypeAndValue(doubleType, CDbl(&HF000000000000000UL)),
New TypeAndValue(doubleType, CDbl(&H70000000000000F0L)),
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&H70000000000000F0L

Would it make sense to use the other value from the description, &H7000000000000400L, instead of this case?

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@AlekseyTs AlekseyTs May 7, 2024 •
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New TypeAndValue(doubleType, CDbl(&H70000000000000F0L)),

Please keep this value #Closed

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I don't think we should keep CDbl(&H70000000000000F0L) because it's misleading: the integer &H70000000000000F0L can't be represented exactly by a Double. As I noted in the PR description, CDbl rounds it down to &H7000000000000000L, which is why it failed to catch this bug.

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Thanks for the explanation. Sounds reasonable.

New TypeAndValue(doubleType, CDbl(&H8000000000000000L)),
New TypeAndValue(doubleType, CDbl(&H7FFFFFFFFFFFFC00L)),
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Should these cases be added to ConstantExpressionConversions2 as well, at line 1169?

New TypeAndValue(typeCodeType, Int32.MinValue),
New TypeAndValue(typeCodeType, Int32.MaxValue),
New TypeAndValue(typeCodeType, CInt(-3)),
Expand Down Expand Up @@ -1165,7 +1166,8 @@ End Class
New TypeAndValue(uint64Type, CULng(18)),
New TypeAndValue(decimalType, CDec(-11.3)),
New TypeAndValue(doubleType, CDbl(&HF000000000000000UL)),
New TypeAndValue(doubleType, CDbl(&H70000000000000F0L)),
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@AlekseyTs AlekseyTs May 7, 2024 •
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New TypeAndValue(doubleType, CDbl(&H70000000000000F0L)),

Please keep this value #Closed

New TypeAndValue(doubleType, CDbl(&H8000000000000000L)),
New TypeAndValue(doubleType, CDbl(&H7FFFFFFFFFFFFC00L)),
New TypeAndValue(typeCodeType, Int32.MinValue),
New TypeAndValue(typeCodeType, Int32.MaxValue),
New TypeAndValue(typeCodeType, CInt(-3)),
Expand Down Expand Up @@ -5095,5 +5097,46 @@ End Module
]]>)
End Sub

<WorkItem(73032, "https://github.com/dotnet/roslyn/issues/73032")>
<Fact()>
Public Sub ConvertLargeDoubleConstantsAndLiteralsToLong()
Dim compilation = CreateCompilationWithMscorlib40AndVBRuntime(
<compilation>
<file name="a.vb"><![CDATA[
Module Program
Sub Main()
System.Console.WriteLine(CType(CDbl(&H8000000000000000L), Long) = ConvertToLong(CDbl(&H8000000000000000L)))
System.Console.WriteLine(CType(CDbl(&H8000000000000400L), Long) = ConvertToLong(CDbl(&H8000000000000400L)))
System.Console.WriteLine(CType(-9.0E+18, Long) = ConvertToLong(-9.0E+18))
System.Console.WriteLine(CType(CDbl(&H8FFFFFFFFFFFFC00L), Long) = ConvertToLong(CDbl(&H8FFFFFFFFFFFFC00L)))
System.Console.WriteLine(CType(CDbl(&H9000000000000000L), Long) = ConvertToLong(CDbl(&H9000000000000000L)))
System.Console.WriteLine(CType(CDbl(&H7000000000000000L), Long) = ConvertToLong(CDbl(&H7000000000000000L)))
System.Console.WriteLine(CType(CDbl(&H7000000000000400L), Long) = ConvertToLong(CDbl(&H7000000000000400L)))
System.Console.WriteLine(CType(9.0E+18, Long) = ConvertToLong(9.0E+18))
System.Console.WriteLine(CType(CDbl(&H7FFFFFFFFFFFFC00L), Long) = ConvertToLong(CDbl(&H7FFFFFFFFFFFFC00L)))
End Sub

Function ConvertToLong(x as Double) As Long
Return CType(x, Long)
End Function
End Module
]]></file>
</compilation>, options:=TestOptions.ReleaseExe.WithOverflowChecks(True))

Dim expectedOutput = <![CDATA[
True
True
True
True
True
True
True
True
True
]]>

CompileAndVerify(compilation, expectedOutput:=expectedOutput).VerifyDiagnostics()
End Sub

End Class
End Namespace