#+TITLE:   lang/cc
#+DATE:    January 16, 2017
#+SINCE:   v2.0
#+STARTUP: inlineimages

* Table of Contents :TOC_3:noexport:
- [[#description][Description]]
  - [[#module-flags][Module Flags]]
  - [[#plugins][Plugins]]
- [[#prerequisites][Prerequisites]]
  - [[#irony-server][irony-server]]
    - [[#macos][MacOS]]
    - [[#arch-linux][Arch Linux]]
    - [[#opensuse][openSUSE]]
  - [[#rtags][rtags]]
- [[#configure][Configure]]
  - [[#project-compile-settings][Project compile settings]]
    - [[#known-issues-with-bear-on-macos][Known issues with bear on macOS]]

* Description
This module adds support for the C-family of languages: C, C++, and Objective-C.

+ Code completion (~company-irony~)
+ eldoc support (~irony-eldoc~)
+ Syntax-checking (~flycheck-irony~)
+ Code navigation (~rtags~)
+ File Templates ([[../../editor/file-templates/templates/c-mode][c-mode]], [[../../editor/file-templates/templates/c++-mode][c++-mode]])
+ Snippets ([[https://github.com/hlissner/doom-snippets/tree/master/cc-mode][cc-mode]], [[https://github.com/hlissner/doom-snippets/tree/master/c-mode][c-mode]], [[https://github.com/hlissner/doom-snippets/tree/master/c++-mode][c++-mode]])
+ Several improvements to C++11 indentation and syntax highlighting.

** Module Flags
+ ~+lsp~ Disables irony+rtags and replaces them with LSP (ccls by default). This
  requires the =:tools lsp= module.

** Plugins
+ [[https://github.com/Kitware/CMake][cmake-mode]]
+ [[https://github.com/chachi/cuda-mode][cuda-mode]]
+ [[https://github.com/liblit/demangle-mode][demangle-mode]]
+ [[https://github.com/jart/disaster][disaster]]
+ [[https://github.com/ludwigpacifici/modern-cpp-font-lock][modern-cpp-font-lock]]
+ [[https://github.com/salmanebah/opencl-mode][opencl-mode]]
+ [[https://github.com/jimhourihan/glsl-mode][glsl-mode]]*
+ [[https://github.com/guidoschmidt/company-glsl][company-glsl]]*
+ =+lsp=
  + [[https://github.com/MaskRay/emacs-ccls][ccls]]
+ =-lsp=
  + [[https://github.com/Sarcasm/irony-mode][irony]]
  + [[https://github.com/ikirill/irony-eldoc][irony-eldoc]]
  + [[https://github.com/Sarcasm/flycheck-irony][flycheck-irony]]
  + [[https://github.com/Sarcasm/company-irony][company-irony]]
  + [[https://github.com/hotpxl/company-irony-c-headers][company-irony-c-headers]]
  + [[https://github.com/Andersbakken/rtags][rtags]]
  + [[https://github.com/Andersbakken/rtags][ivy-rtags]]
  + [[https://github.com/Andersbakken/rtags][helm-rtags]]

* Prerequisites
This module requires

+ irony-server
+ rtags

** irony-server
Irony powers the code completion, eldoc and syntax checking systems.

After installing its dependencies, run ~M-x irony-install-server~ in Emacs.

*** MacOS
Due to linking issues, MacOS users must compile irony-server manually:

#+BEGIN_SRC sh
brew install cmake
brew install llvm  # 1gb+ installation! May take a while!

git clone https://github.com/Sarcasm/irony-mode irony-mode
mkdir irony-mode/server/build
pushd irony-mode/server/build

DEST="$HOME/.emacs.d/.local/etc/irony-server/"
cmake -DCMAKE_INSTALL_RPATH_USE_LINK_PATH=ON \
      -DCMAKE_INSTALL_PREFIX="$DEST" ../
cmake --build . --use-stderr --config Release --target install

install_name_tool -change @rpath/libclang.dylib \
    /usr/local/opt/llvm/lib/libclang.dylib \
    "$DEST/bin/irony-server"

# cleanup
popd
rm -rf irony-mode
#+END_SRC

*** Arch Linux
#+BEGIN_SRC sh
pacman -S clang cmake
#+END_SRC

*** openSUSE
#+BEGIN_SRC sh :dir /sudo::
sudo zypper install clang cmake
#+END_SRC

** rtags
Code navigation requires an [[https://github.com/Andersbakken/rtags][rtags]] server (~rdm~) installed. This should be
available through your OS's package manager.

This module will auto-start ~rdm~ when you open C/C++ buffers (so long as one
isn't already running). If you prefer to run it yourself:

#+BEGIN_SRC sh
rdm &
rc -J $PROJECT_ROOT  # loads PROJECT_ROOT's compile_commands.json
#+END_SRC

* Configure
** Project compile settings
By default, a set of default compile settings are defined in
~+cc-default-compiler-options~ for C, C++ and Objective C. Irony, rtags and
flycheck will fall back to these.

To make these tools aware of project specific build settings, you need a JSON
[[https://sarcasm.github.io/notes/dev/compilation-database.html#ninja][compilation database]] present (i.e. a ~compile_commands.json~ file).

There are [[https://sarcasm.github.io/notes/dev/compilation-database.html][many ways to generate one]]. I use [[http://www.cmake.org/][CMake]] or [[https://github.com/rizsotto/Bear][bear]]:

#+BEGIN_SRC sh
# For CMake projects
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON .

# For non-CMake projects
make clean
bear make
#+END_SRC

Use ~M-x +cc/reload-compile-db~ to reload your compile db in an already-open
C/C++/ObjC buffer.

*** Known issues with bear on macOS
MacOS' [[https://support.apple.com/en-us/HT204899][System Integrity Protection (SIP)]] might interfere with bear if ~make~ is
under ~/usr/bin/~ which results in an empty compilation database.

From the bear [[https://github.com/rizsotto/Bear#empty-compilation-database-on-os-x-captain-or-fedora][readme]]:

#+begin_quote
Security extension/modes on different operating systems might disable library
preloads. This case Bear behaves normally, but the result compilation database
will be empty. (Please make sure it's not the case when reporting bugs.) Notable
examples for enabled security modes are: OS X 10.11 (check with csrutil status |
grep 'System Integrity Protection'), and Fedora, CentOS, RHEL (check with
sestatus | grep 'SELinux status').

Workaround could be to disable the security feature while running Bear. (This
might involve reboot of your computer, so might be heavy workaround.) Another
option if the build tool is not installed under certain directories. Or use
tools which are using compiler wrappers. (It injects a fake compiler which does
record the compiler invocation and calls the real compiler too.) An example for
such tool might be scan-build. The build system shall respect CC and CXX
environment variables.
#+end_quote

A workaround might be to install ~make~ via Homebrew which puts ~gmake~
under ~/usr/local/~.

#+BEGIN_SRC sh
brew install make
#+END_SRC

#+BEGIN_SRC sh
make clean
bear gmake
#+END_SRC

Additional info:
+ [[https://github.com/rizsotto/Bear/issues/158][Empty compilation database with compiler in /usr/local]]
+ [[https://github.com/rizsotto/Bear/issues/152][Workaround for 'Empty compilation database on OS X Captain]]
