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C++ Exception Specifications
I am not convinced that going from dynamic exception specifications (“throw (T1, …)”) to noexcept specifications in C++11 is necessarily a good thing. I understand the rationale behind...
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Stealth Mode
Browsers and email clients typically offer a mode in which automatic access to remote content (like loading a linked graphic) is blocked. This helps improve both privacy (so the other end cannot track...
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Implicit Boolean Conversions in C++
Implicit conversion in C++, inherited from C, is a well-known source of subtle problems. Coming across a place in the LibreOffice code base where a literal true was implicitly converted to an integer...
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Clang Plugins on Mac
The Xcode-provided Clang appears not be bring along the include files needed for plugins, so LibreOffice never ran its set of Clang plugins when building on Mac OS X. Until now. What works is to build...
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Heisenbug
Ever since uprading to Fedora 20 “Heisenbug,” on a whim, I seleted the OpenJDK 1.8.0 pre-release as the default Java alternative. LibreOffice builds and runs fine with it (after some minor tweaks, at...
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GNU make 4 –output-sync
The GNU make 4 --output-sync feature no longer mangles the output from multiple recipes run in parallel, which is great. However, tools will then typically stop to generate ANSI color codes, which is...
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Stacked Bugs
ZCodec::ReadAsynchron was as bad as it could get. It took an SvStream instance by reference (rIStm) and did a handful of calls on that. But, sometimes, it would also remember that IStm in a class...
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dynamic_cast for the price of static_cast
At least for polymorphic types, the cool -fsanitize=undefined feature at runtime flags any broken downcasts, effectively turning all casts into dynamic_casts (which are often avoided in the code due to...
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Bottoming Out
When you have a class like class C { C(): hasId(false) {} // ... private: // ... bool hasId; int id; // iff hasId }; instances of which may under certain circumstances be labeled with an ominous,...
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Evil Casts
Spot the difference in #include <iostream> struct S1 { int s1 = 2; }; struct S2; S2 * f(S1 * s) { return (S2 *) s; } struct T { int t = 1; }; struct S2: T, S1 {}; int main() { S2 s2; std::cout...
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Users of Clang plus glibc, beware
On the one hand, Clang conservatively (and somewhat shizophrenically) claims it is GCC 4.2, by predefining __GNUC__ = 4 and __GNUC_MINOR__ = 2. On the other hand, glibc headers contain a number of...
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Win some, lose some
Seeing recent LibreOffice commit static const to avoid re-init all the time + c++11 got me thinking. (What the code does is check whether a given rtl::OUString instance is among a statically known...
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On filling a vector
In C++11, what is the cheapest way to create a std::vector<T> with a bunch of statically known T elements (in terms of the number of special member functions of T invoked)? In other words, which...
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ODR RTTI DSO
In C++, two types that have the same (fully qualified) name must be the same. The One Definition Rule (ODR) is there to ensure that, even if the types appear in different compilation units. C++...
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LibreOffice in a Box
I had the pleasure of presenting my initial work on packaging LibreOffice as a sandboxed xdg-app bundle at GUADEC over the weekend. Additionally, I dumped my experimental xdg-app repo for my...
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Non-Obvious
Program 1: #define min(a, b) ((a) < (b) ? (a) : (b)) struct S { static int const n = 0; }; int main() { return min(S::n, 1); } Program 2: #include <algorithm> struct S { static int const n =...
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GCC 6
Some notes on building LibreOffice master (towards LO 5.2) with recent GCC trunk (towards GCC 6.0): I ran into two open bugs with GCC that for now need workaround patches to be applied to LO: PR69273...
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libc++/libc++abi on Linux
LibreOffice bug report “Build failure with clang++/libc++ on Linux x86_64” and reports about a similar failure when trying to build on NetBSD made me look at building LibreOffice on Linux with Clang...
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Between an assert and a [[fallthrough]]
LibreOffice now has Clang -Wimplicit-fallthrough enabled to catch places where a break has been missing between cases in a switch statement. See “Re: clang -Wimplicit-fallthrough and missing breaks”...
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LibreOffice.flatpak
Flatpak is the new name of xdg-app. So following up on my previous LibreOffice in a Box post, here is some more technical detail on how an upcoming LibreOffice 5.2 will be available as a Flatpak...
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