Using Atom as a C/C++ Ide (linux)

I dont like heavyweight IDEs such as eclipse or even VSCode/Codium.

I much prefer light ones, such as netbeans. 

I want them to be just a thin wrapper on top of my CMake projects, and that they start in a second or so.

For quick edit, (N)Vim +  coc.vim is incredibly powerful, but for big projects i  prefer something more comfortable.

So i gave Atom a try, and it's pretty good. Really good actually.

The thing is you have to install a bunch of plugins to configure it to be a C/C++ IDE.

 And as a bonus, the code completion setup is similar to the setup for coc.vim, so i can setup it once, and it works for both.

Coc.vim is superior imho for c++, but the Atom is more confortable for large projects.

Atom configuration

So here we go (ubunto 20, it 's a bit more complicated for windows but similar ( use chocolatey for example) :

1- Install  Atom . Nothing special here.

2- Install the following plugins. Edit->Preferences->Install

linter

linter-gcc

atom-ide-base

atom-ide-ui

atom-ide-definitions

ide-c-cpp

ide-ccls

build

build-cmake

3- install ccls through apt/.... Be careful if you install ccls from source it might not work (different version ?)

4- install compdb using pip : pip3 install compdb

5- make sure ccls and compdb are your path : which ccls && which compdb

6- Preferences -> Core -> untick Exclude VCS ignored Paths. This is needed for global search to work.

7- Preference->Package->Autocomplete plus ->Settings -> Keymap for confirming a suggestion -> tab

8- Restart atom

Per project configuration

1- Go to your project folder (cmake based!)

2- Create the code database with  the following commands (put them in a .sh file)

mkdir -p buildAtom

cd buildAtom

cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=True ..

cd ..

compdb -p  buildAtom/ list > compile_commands.json

We are creating a fake cmake build where we ask cmake for dependencies and feed that to ccls. That will enable code completion etc..

3- Create a default CMakeSettings.json (if you dont it will NOT Work properly, even if it's basically defaults)

{
 "configurations": [
   {
     "name": "Debug",
     "generator": "Unix Makefiles",
     "configurationType" : "Debug",
      "buildRoot":  "${projectDir}/build",
     "cmakeCommandArgs":  "",
     "buildCommandArgs": "",
     "ctestCommandArgs":  "",
     "variables": [{
       "name": "TEST_VAR",
       "value": "ON"
       }]
   }
 ]
}

4- File -> addFolder : your favorite project

The basic C/C++ setup is done. You can tweak things  (compilation flags...) etc.. but that setup works "as-is" as a start. 

You can toggle between generate cmake project and build cmake project with the pulldown menu on the bottom left (default is Debug:generate you probably want  Debug:build all)

That includes :

• Syntax highlighting
• On the fly code suggestion
• On the fly linter (with some false warnings if you didnt set it up completely, but good enough imho)

Now you use the following default keybindings :

• Ctrl+Click on a symbol : Go to definition
• Ctrl+Alt+B : Generate cmake or build (change it through the small menu on the bottom left)
• Ctrl+Alt+H : Go to next build error

Of course you can now add other plugins to your liking (themes, cmake syntax, code formating,....)

NB:  Atom works VERY well for rust too.

The only thing i'm not too happy with is to get the list of places where a symbol is used.

With coc.vim 'gr' will do it instantly

With atom, the only thing I've found to work is global search, which is slow and clunky.