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List: kde-frameworks-devel
Subject: Re: Review Request 130139: Set QT_NO_EXCEPTIONS for *.mm files
From: René J.V. Bertin <rjvbertin () gmail ! com>
Date: 2017-05-25 13:20:05
Message-ID: 20170525132005.10655.68612 () mimi ! kde ! org
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> On May 25, 2017, 2:26 p.m., René J.V. Bertin wrote:
> > src/kdeinit/CMakeLists.txt, line 6
> > <https://git.reviewboard.kde.org/r/130139/diff/1/?file=496032#file496032line6>
> >
> > I think you'll need to investigate this issue further first. I've been building \
> > (and patching) KInit since 5.16.0 or so and never run into this issue (neither \
> > have the other testers of my to-be-official MacPorts ports).
> > I just checked (with AppleClang and macports-clang-4.0): all of KInit is built \
> > with `-fno-exceptions`, which has been the default for quite a while now (see \
> > KDECompilerSettings in the ECM). Yet for me QT_NO_EXCEPTIONS is NOT defined when \
> > I build kinit_mac.mm (nor when I include qlist.h and presumably not in the other \
> > files either).
> > Which raises a number of questions:
> > 1. why is QT_NO_EXCEPTIONS not required on my end, but it is on your end (or with \
> > HomeBrew's build recipes)? 2. is this related to how Qt is built?
> > 3. why is only kinit_mac.mm concerned, or more generally, why would this be an \
> > ObjC++ issue?
> > Either way, the real issue here lies in KDE's disabling of exceptions, and Qt's \
> > lacking magic in qglobal.h (around line 632 in Qt 5.8.0) that defines \
> > QT_NO_EXCEPTIONS as needed when GCC is being used. I haven't verified it that \
> > test can be extended to clang too (it works with GCC on Mac) but it seems much \
> > more reasonable to define QT_NO_EXCEPTIONS in the ECM than as suggested here on a \
> > case-by-case basis.
> > -2 as is thus, as far as I'm concerned.
>
> René J.V. Bertin wrote:
> To make things more interesting, here's the preprocessed QList method where the \
> error cited above originates:
> ```
> template <typename T>
> inline typename QList<T>::iterator QList<T>::insert(iterator before, const T &t)
> {
> do { } while ((false) && (isValidIterator(before)));
>
> int iBefore = int(before.i - reinterpret_cast<Node *>(p.begin()));
> Node *n = 0;
> if (d->ref.isShared())
> n = detach_helper_grow(iBefore, 1);
> else
> n = reinterpret_cast<Node *>(p.insert(iBefore));
> try {
> node_construct(n, t);
> } catch (...) {
> p.remove(iBefore);
> throw;
> }
> return n;
> }
> ```
>
> which shows that even on my end I should be getting an error when compiling with \
> `-fno-exceptions`.
https://bugreports.qt.io/browse/QTBUG-61034
- René J.V.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/130139/#review103241
-----------------------------------------------------------
On May 25, 2017, 1:37 p.m., Harald Fernengel wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/130139/
> -----------------------------------------------------------
>
> (Updated May 25, 2017, 1:37 p.m.)
>
>
> Review request for KDE Frameworks and René J.V. Bertin.
>
>
> Repository: kinit
>
>
> Description
> -------
>
> Seems that some versions of clang default to build *.mm files with
> exceptions disabled, so compilation would fail with:
>
> include/QtCore/qlist.h:522:9: error: cannot use 'throw' with exceptions disabled
>
>
> Diffs
> -----
>
> src/kdeinit/CMakeLists.txt f00dd77baa95dbe7583e08760302951446aff387
>
> Diff: https://git.reviewboard.kde.org/r/130139/diff/
>
>
> Testing
> -------
>
>
> Thanks,
>
> Harald Fernengel
>
>
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<tr> <td>
This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/130139/">https://git.reviewboard.kde.org/r/130139/</a>
</td>
</tr>
</table>
<br />
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On May 25th, 2017, 2:26 p.m. CEST, <b>René J.V. \
Bertin</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;">
<table width="100%" border="0" bgcolor="white" style="border: 1px solid #C0C0C0; \
border-collapse: collapse; margin: 2px padding: 2px;"> <thead>
<tr>
<th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;"> <a \
href="https://git.reviewboard.kde.org/r/130139/diff/1/?file=496032#file496032line6" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/kdeinit/CMakeLists.txt</a> <span style="font-weight: normal;">
(Diff revision 1)
</span>
</th>
</tr>
</thead>
<tbody>
<tr>
<th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th> <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td> <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">6</font></th> <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> \
set_source_files_properties(kinit_mac.mm PROPERTIES COMPILE_DEFINITIONS \
QT_NO_EXCEPTIONS)</pre></td> </tr>
</tbody>
</table>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I \
think you'll need to investigate this issue further first. I've been building (and \
patching) KInit since 5.16.0 or so and never run into this issue (neither have the \
other testers of my to-be-official MacPorts ports).</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I \
just checked (with AppleClang and macports-clang-4.0): all of KInit is built with \
<code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: \
normal;margin: 0;line-height: inherit;">-fno-exceptions</code>, which has been the \
default for quite a while now (see KDECompilerSettings in the ECM). Yet for me \
QT_NO_EXCEPTIONS is NOT defined when I build kinit_mac.mm (nor when I include qlist.h \
and presumably not in the other files either).</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Which \
raises a number of questions: 1. why is QT_NO_EXCEPTIONS not required on my end, but \
it is on your end (or with HomeBrew's build recipes)? 2. is this related to how Qt is \
built? 3. why is only kinit_mac.mm concerned, or more generally, why would this be an \
ObjC++ issue?</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Either way, the real issue here lies in KDE's \
disabling of exceptions, and Qt's lacking magic in qglobal.h (around line 632 in Qt \
5.8.0) that defines QT_NO_EXCEPTIONS as needed when GCC is being used. I haven't \
verified it that test can be extended to clang too (it works with GCC on Mac) but it \
seems much more reasonable to define QT_NO_EXCEPTIONS in the ECM than as suggested \
here on a case-by-case basis.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">-2 as is thus, as far \
as I'm concerned.</p></pre> </blockquote>
<p>On May 25th, 2017, 2:51 p.m. CEST, <b>René J.V. Bertin</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">To \
make things more interesting, here's the preprocessed QList method where the error \
cited above originates:</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;"><div class="codehilite" \
style="background: #f8f8f8"><pre style="line-height: 125%"><span></span>template \
<typename T> inline typename QList<T>::iterator \
QList<T>::insert(iterator before, const T &t) {
do { } while ((false) && (isValidIterator(before)));
int iBefore = int(before.i - reinterpret_cast<Node *>(p.begin()));
Node *n = 0;
if (d->ref.isShared())
n = detach_helper_grow(iBefore, 1);
else
n = reinterpret_cast<Node *>(p.insert(iBefore));
try {
node_construct(n, t);
} catch (...) {
p.remove(iBefore);
throw;
}
return n;
}
</pre></div>
</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">which shows that even on my end I should be getting an \
error when compiling with <code style="text-rendering: inherit;color: \
#4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">-fno-exceptions</code>.</p></pre> </blockquote>
</blockquote>
<pre style="margin-left: 1em; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">https://bugreports.qt.io/browse/QTBUG-61034</p></pre> <br />
<p>- René J.V.</p>
<br />
<p>On May 25th, 2017, 1:37 p.m. CEST, Harald Fernengel wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; \
-webkit-border-radius: 6px;"> <tr>
<td>
<div>Review request for KDE Frameworks and René J.V. Bertin.</div>
<div>By Harald Fernengel.</div>
<p style="color: grey;"><i>Updated May 25, 2017, 1:37 p.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
kinit
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">Seems that some versions of clang default to build *.mm files with \
exceptions disabled, so compilation would fail with:
include/QtCore/qlist.h:522:9: error: cannot use 'throw' with exceptions \
disabled</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/kdeinit/CMakeLists.txt <span style="color: \
grey">(f00dd77baa95dbe7583e08760302951446aff387)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/130139/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>
--===============6652898491301653241==--
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