SamatsWiki

• Diff for "CodingStyle/C++"

See also:

• CheatSheet/Gcc

• VisualStudio

C++ style guides

• Google

• LLVM

• Chrome/Chromium

• Mozilla

• WebKit

• Qt's Coding Style and Coding Conventions

• isocpp/CppCoreGuidelines: The C++ Core Guidelines are a set of tried-and-true guidelines, rules, and best practices about coding in C++, from Bjarne Stroustrup and Herb Sutter. More easily readable version

`const` correctness

• GotW #6: Const-Correctness

• http://www.parashift.com/c++-faq-lite/const-correctness.html

Formatting

ClangFormat: auto-formats C++ code

• Git hook running clang-format. Don't use this!

Static analysis tools

• Clang-Tidy: C/C++ linting tool, à la Google's cpplint.

clang-tidy -checks='*' *.cpp -- -std=c++11

• Clang Static Analyzer: sets CC and CXX to use alternate compiler to do analysis

• Cppcheck; github:danmar/cppcheck

# Highest severity warnings only (i.e. memory leaks, etc)
cppcheck --enable=all *.cpp
# Everything except style-related linting
cppcheck --enable=warning,performance,portability,information,missingInclude \
         --std=c++11 --library=std.cfg --verbose --quiet \
         *.cpp

Overview articles:

• Add cppcheck and clang-format for a cmake project

Thread safety analysis (TSA)

Documentation:

• Thread Safety Analysis in C and C++: CMU blog article on TSA

• Thread safety analysis support for libc++, annotating mutex, lock_guard, etc

• Hacker News discussion on thread safety analysis in clang

Example projects:

• ClangBuiltLinux/thread-safety-analysis: Linux kernel w/ TSA annotations

• Chromium, annotation macros, from base/thread_annotations.h. Macros are named different, and they use deprecated TSA names.

Lifetime safety analysis

• Lifetime profile v1.0 posted, initial blog post by Herb Sutter, with link to the Lifetime profile v1.0 paper

• mgehre/llvm-project: clang implementation

• note: gsl = Guidelines Support Library

Stuff I never remember

• Namespacing enums in pre-C++11: https://stackoverflow.com/questions/482745/namespaces-for-enum-types-best-practices#484304

Unnecessary copies w/ `auto`

Beware unncessary copies w/ auto; default semantics is to make a copy.

// Typically there's no reason to copy.
for (const auto &Val : Container) { observe(Val); }
for (auto &Val : Container) { Val.change(); }

// Remove the reference if you really want a new copy.
for (auto Val : Container) { Val.change(); saveSomewhere(Val); }

// Copy pointers, but make it clear that they're pointers.
for (const auto *Ptr : Container) { observe(*Ptr); }
for (auto *Ptr : Container) { Ptr->change(); }

For iterating over maps:

// Nothing changed
for (const auto& [key, value]: some_map) { observ(value); }
for (auto& [key, value]: some_map) { value.change(); }

Don't evaluate `end()` in loops

// BAD
BasicBlock *BB = ...
for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
  // ... use I ...

// GOOD (unless you are mutating BB; use the above loop if you are, and document you are doing so)
BasicBlock *BB = ...
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
  // ... use I ...

Notes:

• https://twitter.com/michael90187356/status/1245830680291848193: no difference? end() will get cached anyway.

Use `const` iterators if not mutating a structure

Expanding on the above:

BasicBlock *BB = ...
for (BasicBlock::const_iterator I = BB->cbegin(), E = BB->cend(); I != E; ++I)
  // ... use I ...

Naming

• "create" and "destroy" for heap-allocated (i.e. pointer) objects
• "init" and "finish" for stack-allocated objects

Dynamic loading of DLL/DSOs

Example of loading OpenCL dynamically. Uses a Python parser script to create special header file with defines that map both functions and does appropriate type conversion. https://github.com/opencv/opencv/pull/1542/files

Boost.DLL: Boost library for easily loading DLLs (e.g. for plugins). Cross platform, but requires runtime libraryes boost_system (integrated into C++11?) and boost_filesystem (integrated into C++17).

https://github.com/knusbaum/CPP-Dynamic-Class-Loading: Class for dynamically loading classes (Linux only)