Meeting 31 August 2017

VS2017 + modules

  • Modules + module identifier => failed build
  • Compiler: msvc140 vs. msvc141
  • Boost: no more std::unary_function and std::binary_function (fixed in 1.64)
  • IncrediBuild support for modules: ???

How to use the C++ Core Guidelines Checker outside of Visual Studio

Post

  • VS2017.3
1<PropertyGroup>
2  <EnableCppCoreCheck>true</EnableCppCoreCheck>
3  <CodeAnalysisRuleSet>
4    CppCoreCheckRules.ruleset
5  </CodeAnalysisRuleSet>
6  <RunCodeAnalysis>true</RunCodeAnalysis>
7</PropertyGroup>

msbuild /p:EnableCppCoreCheck=true
/p:RunCodeAnalysis=true
/p:CodeAnalysisRuleSet=CppCoreCheckRules.ruleset ...

Software development 450 words per minute

How a blind person uses Visual Studio

Functional data structures in C++ by Bartosz Milewski, C++Now 2014

  • GitHub
  • Blog post
  • C++ (naive implementation) vs. Haskell is 1000x slower:
    • heap allocation: big blobs vs. small chunks
    • smart pointers vs. GC
    • native (non-pooled) threads vs. lightweight threads
    • sub-optimal synchronisation
    • not using move semantics properly
    • std::function allocates

David Stone - Writing Robust Code - Meeting C++ 2014

Story

MTuner

GitHub

MTuner is a C/C++ memory profiler and memory leak finder for Windows, PS4, PS3, etc.

MTuner utilizes a novel approach to memory profiling and analysis, keeping entire time-based history of memory operations. This gives an unique insight in memory related behavior of your software by making queries over the entire data set.

Licence: BSD-2

Visual C++ for Linux Development with CMake

Post

  • Requires VS 2017 15.4

pybind11

GitHub

  • Seamless operability between C++11 and Python
  • Header only
  • Exposes C++ types in Python and vice versa, mainly to create Python bindings of existing C++ code
  • Similar to Boost.Python library

C++17: file system

C++ documentation generators

C++/WinRT

  • Modern C++ Blog by Kenny Kerr
  • GitHub
  • C++17
  • Coroutines
  • Clang support
  • [[deprecated]]
  • Simplified ABI interop
  • “Optimized agility implementation”??? IAgileObject :-|

libnyquist: audio decoding library

  • GitHub
  • C++11
  • Ogg Vorbis, FLAC, Wave, MIDI, MOD etc.
  • BSD licence

FlaggedT: type level flagging

Flagged<T> offers multiple wrapper types which allow you to add properties to your variables at type level. The wrapped types can still be used as the inner type, thanks to operator overloading.

  • GitHub
  • MIT licence
  • Single header

Top 20 C++ multithreading mistakes and how to avoid them

Honestly disappointed that list was in order. What a missed opportunity.

HexType: Efficient Detection of Type Confusion Errors for C++

PDF

  • Run-time defences against type confusion errors (bad casts)
  • Less run-time overhead and better detection than TypeSan, CaVer, UBSan
  • LLVM-based

Custom type traits

Post

 1// only WANTED type available
 2template<typename WANTED, typename...>
 3struct can_be_used_as : std::true_type
 4{};
 5
 6// Processes all given types
 7template<typename WANTED,
 8         typename HEAD,
 9         typename... TAIL>
10struct can_be_used_as<WANTED, HEAD, TAIL...>
11    : std::integral_constant<
12        bool,
13        (std::is_same<WANTED,HEAD>{} ||
14        std::is_base_of<WANTED,HEAD>{} ||
15        std::is_convertible<HEAD,WANTED>{}) &&
16        can_be_used_as<WANTED, TAIL...>{}>
17{};

Simplify your type traits with C++14 variable templates

Post

Before:

1template <typename T>
2struct is_float {
3    static constexpr bool value =
4        std::is_same<T, float>::value;
5};

or

1template <typename T>
2using is_float =
3std::integral_constant<bool,
4                       std::is_same<T, float>::value>;

Usage:

1template <typename T>
2void test(T t){
3    if (is_float<T>::value){
4        std::cout << "I'm a float" << std::endl;
5    } else {
6        std::cout << "I'm not a float" << std::endl;
7    }
8}

After:

1template <typename T>
2constexpr is_float = std::is_same_v<T, float>;

Usage:

1template <typename T>
2void test(T t){
3    if (is_float<T>){
4        std::cout << "I'm a float" << std::endl;
5    } else {
6        std::cout << "I'm not a float" << std::endl;
7    }
8}

Metabench: compile-time benchmarks

  • Author: Louis Dionne
  • GitHub
  • A single CMake module
  • Requires CMake 3.1 and Ruby 2.1
  • Works with CMake and Ninja
  • Boost licence

Ignore std::bad_alloc?

Reddit

On Windows, thrown exceptions are copied onto the stack. Destructors and catch blocks are “called” with all of the previous function frames still on the stack. Only when the exception is handled is the stack pointer popped. This has the unfortunate side effect that rethrowing an exception in a deep call stack can cause stack exhaustion.

With the Itanium ABI (Linux, Mac, etc.), the exception is pretty much forced to be on the heap. The compiler will emit calls to void *__cxa_allocate_exception(size_t) and void __cxa_free_exception(void *). However, the implementations of those functions aren’t required to use new. The LLVM implementation uses malloc, and if that fails, it goes to an emergency fallback store of 512 bytes.

If you’re running on Linux then all memory allocations where the size is less than the physical ram succeed because it uses overcommit. All of them, whether there’s enough available memory left or not. Your application will just crash when you try to use it.

Two chevrons