[Libreoffice] Assertions and Logging

[Caolán McNamara]

On Mon, 2011-11-28 at 12:51 +0100, Michael Stahl wrote:
> finally, i have deployed our new aborting assertions for some definitely
> wrong cases in SwIndex:
> http://cgit.freedesktop.org/libreoffice/core/commit/?id=0d2a6999fc320843e4db0c99d961414416a8451c

And I have abort on make subsequentcheck in writer on getting the anchor
for an embeddedobj, i.e. sw.SwXTextEmbeddedObject test

Here's what I see...

in __GI___assert_fail (assertion=0x7fffdbf615b8 "m_pIndexReg ==
rIndex.m_pIndexReg", 
file=0x7fffdbf61278
"/home/caolan/LibreOffice/core/sw/source/core/bastyp/index.cxx",
line=382, function=
0x7fffdbf616a0 "bool SwIndex::operator<(const SwIndex&) const") at
assert.c:105

Digging, I see the m_pIndexReg is zero-ed out at...

SwFmtAnchor::SetAnchor (this=0x7fffdd1ac6a0, pPos=0x7fffdd1ac958)
at /home/caolan/LibreOffice/core/sw/source/core/layout/atrfrm.cxx:1508

fuller logs attached.

The zeroing out code is...

void SwFmtAnchor::SetAnchor( const SwPosition *pPos )
{
    delete pCntntAnchor;
    pCntntAnchor = pPos ? new SwPosition( *pPos ) : 0;
        //AM Absatz gebundene Flys sollten nie in den Absatz
hineinzeigen.
    if (pCntntAnchor &&
        ((FLY_AT_PARA == nAnchorId) || (FLY_AT_FLY == nAnchorId)))
    {
        pCntntAnchor->nContent.Assign( 0, 0 );
    }
}

So we are a FLY_AT_PARA anchor, so the SwIndex m_pIndexReg is set to 0
from the first arg, comment is in German, but I guess the jist of it is 
"paragraph anchors shouldn't point into a specific location in the
paragraph", which seems plausible.

Later on though when we want to find the anchor we end up comparing
SwIndex'es and the assert fires, so how do we fix this ?

a) Tweak the SwIndex::operator to allow NULL m_pIndexReg when m_nIndex
is 0 and sort them before non-NULL m_pIndexReg ?
b) Do that in SwPosition::operator< instead ?.
c) Not null out the m_pIndexReg in the first place in SetCntntAnchor,
and just set it to the 0th element
d) custom compare in lcl_MarkOrderingByStart, lcl_Lower etc ?

C.
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