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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_UNCONFIRMED "
title="UNCONFIRMED - Invoking a Basic routine with ByRef Long or Double parameter does not return modified value"
href="https://bugs.documentfoundation.org/show_bug.cgi?id=133889">133889</a>
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<th>Summary</th>
<td>Invoking a Basic routine with ByRef Long or Double parameter does not return modified value
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<th>Product</th>
<td>LibreOffice
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<th>Version</th>
<td>Inherited From OOo
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<th>Hardware</th>
<td>All
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<th>OS</th>
<td>All
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<th>Status</th>
<td>UNCONFIRMED
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>BASIC
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<th>Assignee</th>
<td>libreoffice-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>mikekaganski@hotmail.com
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<th>CC</th>
<td>andreas.heinisch@yahoo.de
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<pre>This is one of two related bug reports (the other is <a class="bz_bug_link
bz_status_UNCONFIRMED "
title="UNCONFIRMED - Invoking a Basic routine with ByRef Variant parameter returns wrong value type"
href="show_bug.cgi?id=133887">bug 133887</a>); attachment
161869 contains the tests for both. Please run TestByRefFromInvoke, and only
check last two lines of output (OutputByRef3 and OutputByRef4) for the purposes
of this bug.
If there is a routine with a ByRef parameter (i.e., inout parameter), invoking
it using XScript::invoke [1] requires passing *in* values through the first
array (sequence), and getting their modified *out* values in the last passed
array. This bug is for explicit Long and Double parameters:
<span class="quote">> Sub Foo(v As Long) ' default ByRef
> v = 100000
> End Sub</span >
<span class="quote">> Sub TestInvoke
> oScript = thisComponent.getScriptProvider().getScript("vnd.sun.star.script:Standard.Module1.Foo?language=Basic&location=document")
> oScript.invoke(Array(0&), aOutInd, aOutArr)
> MsgBox aOutArr(0) & " " & TypeName(aOutArr(0))
> End Sub</span >
TestInvoke above passes "0&" (i.e., an explicit Long value) as initial value of
the variable passed to the Foo, and expects to get the modified value in the
aOutArr(0) - i.e., it should output "100000 Long".
However, the actual returned value is 0 of type *Integer*. It is possible to
get the correct result by modifying the value passed to invoke call like this:
<span class="quote">> oScript.invoke(Array(200000), aOutInd, aOutArr)</span >
So it is not enough to pass an explicitly-typed long value; it turns into a
smaller type if its value fits that smaller value.
The conversion was introduced in
<a href="https://git.libreoffice.org/core/+/11f9aa4fcb2ad0a5fada8561c7041e7f25a059fc">https://git.libreoffice.org/core/+/11f9aa4fcb2ad0a5fada8561c7041e7f25a059fc</a>,
and was made conditional (dependent on VBASupport) in
<a href="https://git.libreoffice.org/core/+/9cdb73ff28c4cd6380412468f34ff10e46292a07">https://git.libreoffice.org/core/+/9cdb73ff28c4cd6380412468f34ff10e46292a07</a>.
The reason for the conversion is expressed as "Choose "smallest" represention
for int values because up cast is allowed, downcast not". I *suppose* that the
idea was that it's possible to call some UNO API like this:
<span class="quote">> Dim n As Long
> n = 1
> oSomeObject.AMethodExpecting16BitValue(n)</span >
... which would fail if value of n would be passed as 32-bit integer to the
method. Thus, I suppose that removal of the conversion could be an incompatible
change breaking infinite number of existing macros (so unacceptable; yet, I
don't have a proof of this suspicion). I also don't know if it's possible to
find a proper condition to disallow downcasting for the purposes of ByRef
parameters.</pre>
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