Function Foo(A as Integer) As Integer
Dim B as Integer

    If A > 0 Then                      ' REM 1
       B = 2                           ' REM 2
       If A > 2 Then B = 3 Else B = 0  ' REM 3 => syntax err
    End If

    Foo = B
End Function

Function Foo2(A as Integer) As Integer
Dim B as Integer

    If A > 0 Then                      ' REM 1
       B = 2                           ' REM 2
       If A > 2 Then B = 3 Else B = 0  ' REM 3 => NO syntax err

    End If

    Foo2 = B
End Function

Confirmed. 
The syntax analyzer is disturbed by any comment at right of a line containing
 if ... then ... else ... 
The comment may be a single apostrophe or a single REM

Further examples:

    >> this throws Unexpected symbol : End Sub
Sub Main
for a = -5 to 3
  if a > 1  then b = 0 else b = 2 REM
next
End Sub


    >> this throws Unexpected symbol : Until
Sub Main1
a= 0
Do
  a = a+1
  if a > 1  then b = 0 else b = 2 rem
Loop Until a > 3
End Sub

Workaround : do not add a comment on a line "if...then...else..."

The comment isn't the problem. As I know only oneliners with only one statement is allowed.

legal:
If <condition> Then <statement>

illegal:
If <condition> Then <statement> Else <statement>


Modify Foo() to

Function Foo(A as Integer) As Integer
Dim B as Integer

    If A > 0 Then                      'comment
       B = 2                           'comment
       If A > 2 Then B = 3 Else B = 0  'comment
       MsgBox( "A" )                   'comment
       MsgBox( "B" )                   'comment
       MsgBox( "C" )                   'comment
       MsgBox( "D" )
    End If

    Foo = B
End Function

Then you will see that the MsgBoxes will not be reached for A>2.

A comment after MsgBox ( "D" ) will also cause the error because the nested If statement is unclosed.

IMHO this isn't an issue, it's an illegal oneliner.

It seems <comment><newline> is treated like a colon.

Sub Foo1( A as Integer )
    If A > 2 Then MsgBox( 0 ) Else MsgBox( 1 )  'comment
    MsgBox( 2 )                                 'comment
    MsgBox( 3 )                   
End Sub

Sub Foo2( A as Integer )
    If A > 2 Then MsgBox( 0 ) Else MsgBox( 1 ) : MsgBox( 2 ) : MsgBox( 3 )                   
End Sub

Foo1 and Foo2 gives the same result.


But nevertheless the parser should give an error if /If/ and /Else/ in one line or it should simply stop at the comment.

mroe said :
illegal:
If <condition> Then <statement> Else <statement>
the parser should give an error if /If/ and /Else/ in one line or it should simply stop at the comment.


Look at Microsoft VBA doc on IF statement:
https://msdn.microsoft.com/en-us/library/gg251599%28v=office.14%29.aspx
The single-line form is accepted for if-then-else :
"You can use the single-line form (first syntax) for short, simple tests. "

This single form is widely used in Basic macros, it must be kept for compatibility. It is not described in the F1 help, but appears in the Wiki Basic Programming Guide.
The statement works correctly if there is no comment in the same line. This restriction is minor, if you know it.

The Basic parser was only allowing Else to end in EOL, not in a comment. I've fixed that in r1720205, so resolving fixed.

I've updated the subject to make it clear what the problem was

Cherry-picked for AOO42X with commit 3b5ec47b15ab141460e2a7c60e19e9a0616b9d3d.

This was fixed and released with AOO 4.1.13:

https://github.com/apache/openoffice/commit/4dcbef3e4f42e9515ba2313db12f4aecd595a57f

I think Damjan cherry-picked the missing test for AOO42X?

(In reply to Matthias Seidel from comment #9)
> This was fixed and released with AOO 4.1.13:
> 
> https://github.com/apache/openoffice/commit/
> 4dcbef3e4f42e9515ba2313db12f4aecd595a57f
> 
> I think Damjan cherry-picked the missing test for AOO42X?

Yes he did, i saw the conversation later and was coming back to reverse this. Thank you for doing it. Sorry for the noise.

No problem!

I wasn't sure myself, so I better looked it up.