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List: kde-core-devel
Subject: Re: Question regarding compatibility for kdecore and KDE4_ENABLE_FINAL
From: Alexander Neundorf <neundorf () kde ! org>
Date: 2012-06-13 16:13:48
Message-ID: 201206131813.49090.neundorf () kde ! org
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On Wednesday 13 June 2012, Michael Pyne wrote:
> Hi all,
>
> Bug 301419 has been reported against kdelibs due to a build failure when
> KDE4_ENABLE_FINAL is used, introduced by some commits of mine to perform
> even more sanity checking in the KSharedDataCache.
>
> These commits use exceptions (as are already used in khtml) since they are
> actually "the right tool" in the context of where they are used, and
> because refactoring everything to use error codes everywhere (ECE) would
> have risked introducing more bugs.
>
> In order to minimize the changes to kdecore I only added the CMake magic to
> enable exceptions for only kshareddatacache.cpp. This doesn't work when
> KDE4_ENABLE_FINAL is used, as the project-wide CXXFLAGS are used in that
> case.
>
> The Mageia devs have a proposed patch [1] to enable exceptions for all of
> kdecore, which fixes the issue. Is it acceptable for me to go this route?
> The only real alternative this late in the game is to back out the sanity
> checks to the 4.8.3 status or to explicitly say that KDE4_ENABLE_FINAL
> will not work for this tarball although it worked for 4.8.3, both of which
> I consider less desirable. But I don't want to make the change if there
> are good reasons to avoid it.
>
> Longer term (for frameworks) KSharedDataCache could be split into its own
> tier if necessary (it only really depends on Qt and KStandardDirs, which
> is now also in Qt...).
In KDE frameworks, i.e. next gen kdelibs, ENABLE_FINAL will not be supported
anymore at all.
AFAIK gcc now actually has a mode to do interobject optimizations, so with
this mode enabled (which we currently don't), ENABLE_FINAL should not be
necessary anymore.
So, personally I do not really care much about ENABLE_FINAL.
Alex
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pre-wrap; } </style></head><body style=" font-family:'Monospace'; \
font-size:9pt; font-weight:400; font-style:normal;"> <p style=" \
margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; \
-qt-block-indent:0; text-indent:0px; -qt-user-state:0;">On Wednesday 13 \
June 2012, Michael Pyne wrote:</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> Hi all,</p> <p style=" \
margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; \
-qt-block-indent:0; text-indent:0px; -qt-user-state:0;">> </p> <p \
style=" margin-top:0px; margin-bottom:0px; margin-left:0px; \
margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> Bug 301419 has been reported against kdelibs due to \
a build failure when</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> KDE4_ENABLE_FINAL is used, introduced by some \
commits of mine to perform</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> even more sanity checking in the \
KSharedDataCache.</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> </p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> These commits use exceptions (as are already used \
in khtml) since they are</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> actually "the right tool" in the context \
of where they are used, and</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> because refactoring everything to \
use error codes everywhere (ECE) would</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> have risked introducing more \
bugs.</p> <p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; \
margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> </p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> In order to minimize the changes to kdecore I only \
added the CMake magic to</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> enable exceptions for only kshareddatacache.cpp. \
This doesn't work when</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> KDE4_ENABLE_FINAL is used, as the project-wide \
CXXFLAGS are used in that</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> case.</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> </p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> The Mageia devs have a proposed \
patch [1] to enable exceptions for all of</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> kdecore, which fixes the issue. Is \
it acceptable for me to go this route?</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> The only real alternative this \
late in the game is to back out the sanity</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> checks to the 4.8.3 status or to \
explicitly say that KDE4_ENABLE_FINAL</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> will not work for this tarball \
although it worked for 4.8.3, both of which</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> I consider less desirable. But I \
don't want to make the change if there</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">> are good reasons to avoid it.</p> \
<p style=" margin-top:0px; margin-bottom:0px; margin-left:0px; \
margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> </p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> Longer term (for frameworks) KSharedDataCache could \
be split into its own</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> tier if necessary (it only really depends on Qt and \
KStandardDirs, which</p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">> is now also in Qt...).</p> <p \
style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;"></p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">In KDE frameworks, i.e. next gen kdelibs, ENABLE_FINAL \
will not be supported anymore at all.</p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">AFAIK gcc now actually has a mode to do \
interobject optimizations, so with this mode enabled (which we currently \
don't), ENABLE_FINAL should not be necessary anymore.</p> <p \
style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;"></p> <p style=" margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;">So, personally I do not really care much about \
ENABLE_FINAL.</p> <p style="-qt-paragraph-type:empty; margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;"></p> <p style=" margin-top:0px; \
margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; \
text-indent:0px; -qt-user-state:0;">Alex</p> <p \
style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; \
margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; \
-qt-user-state:0;"></p></body></html>
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