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jerrymarino / iCompleteMe

Swift comprehension in Vim: code completion and diagnostics
GNU General Public License v3.0
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iCompleteMe: Swift comprehension in Vim

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Intro

Featuring

SwiftySwiftVimPreview

Warning: it's in a bleeding edge, pre-alpha state.

Background

iCompleteMe is based on YouCompleteMe. After spending a over a year attempting to implement Swift support for YouCompleteMe, I found that it wasn't possible to achieve ideal behavior under the conventions of YCM; iCM spawned.

Instead of shoehorning Swift into completion behaviors that work OK for other languages, iCompleteMe implements behaviors which are ideal for Swift.

Additionally, iCompleteMe's core subsystems only work with Swift. The codebase has a significantly smaller footprint, which makes it easier to install, easier to reason about, and more stable on the CI ( in theory ).

The name iCompleteMe is a statement about developing a system that considers ideal behaviors for an individual language and a tribute to Valloric's and the YCM's teams legacy.

It can exist in parallel to YouCompleteMe: use iCompleteMe for the Swift files.

Installation

Mac OS X

These instructions (using install.py) are the quickest way to install iCompleteMe, however they may not work for everyone. If the following instructions don't work for you, check out the full installation guide.

Install the latest version of MacVim. Yes, MacVim. And yes, the latest.

If you don't use the MacVim GUI, it is recommended to use the Vim binary that is inside the MacVim.app package (MacVim.app/Contents/MacOS/Vim). To ensure it works correctly copy the mvim script from the MacVim download to your local binary folder (for example /usr/local/bin/mvim) and then symlink it:

ln -s /usr/local/bin/mvim vim

Install iCompleteMe with Vundle.

Remember: iCM is a plugin with a compiled component. If you update iCM using Vundle and the ycm_core library APIs have changed (happens rarely), iCM will notify you to recompile it. You should then rerun the install process.

NOTE: If you want Swift completion, you MUST have the latest Xcode installed along with the latest Command Line Tools (they are installed automatically when you run clang for the first time, or manually by running xcode-select --install)

Install CMake. Preferably with Homebrew, but here's the stand-alone CMake installer.

If you have installed a Homebrew Python and/or Homebrew MacVim, see the FAQ for details.

Simply run:

cd ~/.vim/bundle/iCompleteMe
./install.py

That's it. You're done. Refer to the User Guide section on how to use iCM. Don't forget that if you want the Swift semantic completion engine to work, you will need to provide the compilation flags for your project to iCM. It's all in the User Guide.

iCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

iCM Relies on SwiftySwiftVim for language support. By default, it links libraries from Xcode ( using whatever Xcode xcode-select points at ). If you'd like to build from source, checkout SwiftySwiftVim's build system for more info

Ubuntu Linux x64

Untested: Requires building SwiftySwiftVim from source.

These instructions (using install.py) are the quickest way to install iCompleteMe, however they may not work for everyone. If the following instructions don't work for you, check out the full installation guide.

Make sure you have Vim 7.4.1578 with Python 2 or Python 3 support. Ubuntu 16.04 and later have a Vim that's recent enough. You can see the version of Vim installed by running vim --version. If the version is too old, you may need to compile Vim from source (don't worry, it's easy).

Install iCompleteMe with Vundle.

Remember: iCM is a plugin with a compiled component. If you update iCM using Vundle and the ycm_core library APIs have changed (happens rarely), iCM will notify you to recompile it. You should then rerun the install process.

Install development tools and CMake: 

sudo apt-get install build-essential cmake

Make sure you have Python headers installed:

sudo apt-get install python-dev python3-dev

cd ~/.vim/bundle/iCompleteMe
./install.py

That's it. You're done. Refer to the User Guide section on how to use iCM. Don't forget that if you want the Swift semantic completion engine to work, you will need to provide the compilation flags for your project to iCM. It's all in the User Guide.

iCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

Fedora Linux x64

Untested: Requires building SwiftySwiftVim from source.

These instructions (using install.py) are the quickest way to install iCompleteMe, however they may not work for everyone. If the following instructions don't work for you, check out the full installation guide.

Make sure you have Vim 7.4.1578 with Python 2 or Python 3 support. Fedora 21 and later have a Vim that's recent enough. You can see the version of Vim installed by running vim --version. If the version is too old, you may need to compile Vim from source (don't worry, it's easy).

Install iCompleteMe with Vundle.

Remember: iCM is a plugin with a compiled component. If you update iCM using Vundle and the ycm_core library APIs have changed (happens rarely), iCM will notify you to recompile it. You should then rerun the install process.

Install development tools and CMake:

sudo dnf install automake gcc gcc-c++ kernel-devel cmake

Make sure you have Python headers installed:

sudo dnf install python-devel python3-devel

cd ~/.vim/bundle/iCompleteMe
./install.py

That's it. You're done. Refer to the User Guide section on how to use iCM. Don't forget that if you want the Swift semantic completion engine to work, you will need to provide the compilation flags for your project to iCM. It's all in the User Guide.

iCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

Windows

Untested: Requires building SwiftySwiftVim from source.

These instructions (using install.py) are the quickest way to install iCompleteMe, however they may not work for everyone. If the following instructions don't work for you, check out the full installation guide.

Important: we assume that you are using the cmd.exe command prompt and that you know how to add an executable to the PATH environment variable.

Make sure you have at least Vim 7.4.1578 with Python 2 or Python 3 support. You can check the version and which Python is supported by typing :version inside Vim. Look at the features included: +python/dyn for Python 2 and +python3/dyn for Python 3. Take note of the Vim architecture, i.e. 32 or 64-bit. It will be important when choosing the Python installer. We recommend using a 64-bit client. Daily updated copies of 32-bit and 64-bit Vim with Python 2 and Python 3 support are available.

Install iCompleteMe with Vundle.

Remember: iCM is a plugin with a compiled component. If you update iCM using Vundle and the ycm_core library APIs have changed (happens rarely), iCM will notify you to recompile it. You should then rerun the install process.

Download and install the following software:

Compiling iCM with semantic support for Swift language:

cd %USERPROFILE%/vimfiles/bundle/iCompleteMe
install.py

You can specify the Microsoft Visual C++ (MSVC) version using the --msvc option. iCM officially supports MSVC 12 (Visual Studio 2013), 14 (2015), and 15 (2017).

That's it. You're done. Refer to the User Guide section on how to use iCM.

iCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

FreeBSD/OpenBSD

Untested: Requires building SwiftySwiftVim from source.

These instructions (using install.py) are the quickest way to install iCompleteMe, however they may not work for everyone. If the following instructions don't work for you, check out the full installation guide.

NOTE: OpenBSD / FreeBSD are not officially supported platforms by iCM.

Make sure you have Vim 7.4.1578 with Python 2 or Python 3 support.

OpenBSD 5.5 and later have a Vim that's recent enough. You can see the version of Vim installed by running vim --version.

FreeBSD 10.x comes with clang compiler but not the libraries needed to install.

pkg install llvm38 boost-all boost-python-libs clang38
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/llvm38/lib/

Install iCompleteMe with Vundle.

Remember: iCM is a plugin with a compiled component. If you update iCM using Vundle and the ycm_core library APIs have changed (happens rarely), iCM will notify you to recompile it. You should then rerun the install process.

Install dependencies and CMake: sudo pkg_add llvm boost cmake

cd ~/.vim/bundle/iCompleteMe
./install.py

That's it. You're done. Refer to the User Guide section on how to use iCM.

iCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

Full Installation Guide

These are the steps necessary to get iCM working on a Unix OS and on Windows.

Note to Windows users: we assume that you are running the cmd.exe command prompt and that the needed executables are in the PATH environment variable. Do not just copy the shell commands. Replace ~ by %USERPROFILE% in them and use the right Vim home directory. It should be vimfiles by default instead of .vim.

See the FAQ if you have any issues.

Remember: iCM is a plugin with a compiled component. If you update iCM using Vundle and the ycm_core library APIs have changed (happens rarely), iCM will notify you to recompile it. You should then rerun the install process.

Please follow the instructions carefully. Read EVERY WORD.

  1. Ensure that your version of Vim is at least 7.4.1578 and that it has support for Python 2 or Python 3 scripting.

    Inside Vim, type :version. Look at the first two to three lines of output; it should say Vi IMproved X.Y, where X.Y is the major version of vim. If your version is greater than 7.4, then you're all set. If your version is 7.4 then look below that where it says, Included patches: 1-Z, where Z will be some number. That number needs to be 143 or higher.

    If your version of Vim is not recent enough, you may need to compile Vim from source (don't worry, it's easy).

    After you have made sure that you have Vim 7.4.1578+, type the following in Vim: :echo has('python') || has('python3'). The output should be 1. If it's 0, then get a version of Vim with Python support.

    On Windows, check also if your Vim architecture is 32 or 64-bit. This is critical because it must match the Python and the iCM libraries architectures. We recommend using a 64-bit Vim.

  2. Install iCM with Vundle (or Pathogen, but Vundle is a better idea). With Vundle, this would mean adding a Plugin 'jerrymarino/iCompleteMe' line to your vimrc.

    If you don't install iCM with Vundle, make sure you have run git submodule update --init --recursive after checking out the iCM repository (Vundle will do this for you) to fetch iCM's dependencies.

  3. Compile the ycm_core library that iCM needs. This library is the C++ engine that iCM uses to get fast completions.

    You will need to have cmake installed in order to generate the required makefiles. Linux users can install cmake with their package manager (sudo apt-get install cmake for Ubuntu) whereas other users can download and install cmake from its project site. Mac users can also get it through Homebrew with brew install cmake.

    On a Unix OS, you need to make sure you have Python headers installed. On a Debian-like Linux distro, this would be sudo apt-get install python-dev python3-dev. On Mac they should already be present.

    On Windows, you need to download and install Python 2 or Python 3. Pick the version corresponding to your Vim architecture. You will also need Microsoft Visual C++ (MSVC) to build iCM. You can obtain it by installing Visual Studio. MSVC 12 (Visual Studio 2013), 14 (2015), and 15 (2017) are officially supported.

    Here we'll assume you installed iCM with Vundle. That means that the top-level iCM directory is in ~/.vim/bundle/iCompleteMe.

    We'll create a new folder where build files will be placed. Run the following:

    cd ~
mkdir ycm_build
cd ycm_build

    Now we need to generate the makefiles. If you DON'T care about semantic support for Swift language, run the following command in the ycm_build directory:

    cmake -G "<generator>" . ~/.vim/bundle/iCompleteMe/third_party/ycmd/cpp

    where <generator> is Unix Makefiles on Unix systems and one of the following Visual Studio generators on Windows:

    • Visual Studio 12 Win64
    • Visual Studio 14 Win64
    • Visual Studio 15 Win64

    Remove the Win64 part in these generators if your Vim architecture is 32-bit.

    For those who want to use the system version of boost, you would pass -DUSE_SYSTEM_BOOST=ON to cmake. This may be necessary on some systems where the bundled version of boost doesn't compile out of the box.

    NOTE: We STRONGLY recommend AGAINST use of the system boost instead of the bundled version of boost. Random things may break. Save yourself the hassle and use the bundled version of boost.

    With that in mind, run the following command in the ycm_build directory:

    cmake -G "<generator>" -DPATH_TO_LLVM_ROOT=~/ycm_temp/llvm_root_dir . ~/.vim/bundle/iCompleteMe/third_party/ycmd/cpp

    where <generator> is replaced like above.

    Now that configuration files have been generated, compile the libraries using this command:

    cmake --build . --target ycm_core --config Release

    The --config Release part is specific to Windows and will be ignored on a Unix OS.

    For those who want to use the system version of libclang, you would pass -DUSE_SYSTEM_LIBCLANG=ON to cmake instead of the -DPATH_TO_LLVM_ROOT=... flag.

    NOTE: We STRONGLY recommend AGAINST use of the system libclang instead of the upstream compiled binaries. Random things may break. Save yourself the hassle and use the upstream pre-built libclang.

    You could also force the use of a custom libclang library with -DEXTERNAL_LIBCLANG_PATH=/path/to/libclang.so flag (the library would end with .dylib on a Mac). Again, this flag would be used instead of the other flags. If you compiled LLVM from source, this is the flag you should be using.

    Running the cmake command will also place the libclang.[so|dylib|dll] in the iCompleteMe/third_party/ycmd folder for you if you compiled with clang support (it needs to be there for iCM to work).

That's it. You're done. Refer to the User Guide section on how to use iCM.

iCM comes with sane defaults for its options, but you still may want to take a look at what's available for configuration. There are a few interesting options that are conservatively turned off by default that you may want to turn on.

Quick Feature Summary

User Guide

General Usage

Knowing a little bit about how iCM works internally will prevent confusion. iCM has several completion engines: an identifier-based completer that collects all of the identifiers in the current file and other files you visit (and your tags files) and searches them when you type (identifiers are put into per-filetype groups).

Client-Server Architecture

iCM has a client-server architecture; the Vim part of iCM is only a thin client that talks to the ycmd HTTP+JSON server that has the vast majority of iCM logic and functionality. The server is started and stopped automatically as you start and stop Vim.

Completion String Ranking

The subsequence filter removes any completions that do not match the input, but then the sorting system kicks in. It's actually very complicated and uses lots of factors, but suffice it to say that "word boundary" (WB) subsequence character matches are "worth" more than non-WB matches. In effect, this means given an input of "gua", the completion "getUserAccount" would be ranked higher in the list than the "Fooguxa" completion (both of which are subsequence matches). A word-boundary character are all capital characters, characters preceded by an underscore and the first letter character in the completion string.

General Semantic Completion

Semantic Compliation

Setup a compilation database

By default, it provides a basic level of completion support: completions within a single file.

In most cases, build options and dependencies need to be specified to have a good experience.

SwiftySwiftVim uses a Compilation Database to import compiler settings. Setup the build system to generate one at the workspace root.

For Xcode Project users, XcodeCompilationDatabase makes this easy.

Diagnostic Display

iCM will display diagnostic notifications for if you. Diagnostics will also be displayed for TypeScript. Since iCM continuously recompiles your file as you type, you'll get notified of errors and warnings in your file as fast as possible.

Here are the various pieces of the diagnostic UI:

The new diagnostics (if any) will be displayed the next time you press any key on the keyboard. So if you stop typing and just wait for the new diagnostics to come in, that will not work. You need to press some key for the GUI to update.

Having to press a key to get the updates is unfortunate, but cannot be changed due to the way Vim internals operate; there is no way that a background task can update Vim's GUI after it has finished running. You have to press a key. This will make iCM check for any pending diagnostics updates.

You can force a full, blocking compilation cycle with the :IcmForceCompileAndDiagnostics command (you may want to map that command to a key; try putting nnoremap <F5> :IcmForceCompileAndDiagnostics<CR> in your vimrc). Calling this command will force iCM to immediately recompile your file and display any new diagnostics it encounters. Do note that recompilation with this command may take a while and during this time the Vim GUI will be blocked.

iCM will display a short diagnostic message when you move your cursor to the line with the error. You can get a detailed diagnostic message with the <leader>d key mapping (can be changed in the options) iCM provides when your cursor is on the line with the diagnostic.

You can also see the full diagnostic message for all the diagnostics in the current file in Vim's locationlist, which can be opened with the :lopen and :lclose commands (make sure you have set let g:icm_always_populate_location_list = 1 in your vimrc). A good way to toggle the display of the locationlist with a single key mapping is provided by another (very small) Vim plugin called [ListToggle][] (which also makes it possible to change the height of the locationlist window), also written by yours truly.

Diagnostic Highlighting Groups

You can change the styling for the highlighting groups iCM uses. For the signs in the Vim gutter, the relevant groups are:

You can also style the line that has the warning/error with these groups:

Note that the line highlighting groups only work when gutter signs are turned on.

The syntax groups used to highlight regions of text with errors/warnings:

Here's how you'd change the style for a group:

highlight IcmErrorLine guibg=#3f0000

Commands

The :IcmRestartServer command

If the ycmd completion server suddenly stops for some reason, you can restart it with this command.

The :IcmForceCompileAndDiagnostics command

Calling this command will force iCM to immediately recompile your file and display any new diagnostics it encounters. Do note that recompilation with this command may take a while and during this time the Vim GUI will be blocked.

You may want to map this command to a key; try putting nnoremap <F5> :IcmForceCompileAndDiagnostics<CR> in your vimrc.

The :IcmDiags command

Calling this command will fill Vim's locationlist with errors or warnings if any were detected in your file and then open it. If a given error or warning can be fixed by a call to :IcmCompleter FixIt, then (FixIt available) is appended to the error or warning text. See the FixIt completer subcommand for more information.

NOTE: The absense of (FixIt available) does not strictly imply a fix-it is not available as not all completers are able to provide this indication. For example, the swift completer provides many fix-its but does not add this additional indication.

The g:icm_open_loclist_on_ycm_diags option can be used to prevent the location list from opening, but still have it filled with new diagnostic data. See the Options section for details.

The :IcmShowDetailedDiagnostic command

This command shows the full diagnostic text when the user's cursor is on the line with the diagnostic.

The :IcmDebugInfo command

This will print out various debug information for the current file. Useful to see what compile commands will be used for the file if you're using the semantic completion engine.

The :IcmToggleLogs command

This command opens in separate windows the logfiles given as arguments or closes them if they are already open in the editor. When no argument is given, list the available logfiles. Only for debugging purpose.

The :IcmCompleter command

This command gives access to a number of additional IDE-like features.

Technically the command invokes completer-specific commands. If the first argument is of the form ft=... the completer for that file type will be used (for example ft=cpp), else the native completer of the current buffer will be used. Call IcmCompleter without further arguments for a list of the commands you can call for the current completer.

See the file type feature summary for an overview of the features available for each file type. See the IcmCompleter subcommands section for more information on the available subcommands and their usage.

Miscellaneous Commands

These commands are for general administration, rather than IDE-like features. They cover things like the semantic engine server instance and compilation flags.

The RestartServer subcommand

Restarts the semantic-engine-as-localhost-server for those semantic engines that work as separate servers that iCM talks to.

An additional optional argument may be supplied for Python, specifying the python binary to use to restart the Python semantic engine.

:IcmCompleter RestartServer /usr/bin/python3.4

The ClearCompilationFlagCache subcommand

TODO:Jerry ( Not Implemented )

iCM caches the flags it gets from the FlagsForFile function in your ycm_extra_conf.py file if you return them with the do_cache parameter set to True. The cache is in memory and is never invalidated (unless you restart Vim of course).

This command clears that cache entirely. iCM will then re-query your FlagsForFile function as needed in the future.

Functions

The icompleteme#GetErrorCount function

Get the number of iCM Diagnostic errors. If no errors are present, this function returns 0.

For example:

  call icompleteme#GetErrorCount()

Both this function and icompleteme#GetWarningCount can be useful when integrating iCM with other Vim plugins. For example, a lightline user could add a diagnostics section to their statusline which would display the number of errors and warnings.

The icompleteme#GetWarningCount function

Get the number of iCM Diagnostic warnings. If no warnings are present, this function returns 0.

For example:

  call icompleteme#GetWarningCount()

Autocommands

The IcmLocationOpened autocommand

This User autocommand is fired when iCM opens the location list window in response to the IcmDiags command. By default, the location list window is opened to full width at the bottom of the screen and its height is set to fit all entries. This behavior can be overridden by using the IcmLocationOpened autocommand which is triggered while the cursor is in the location list window. For instance:

function! s:CustomizeIcmLocationWindow()
  " Move the window to the top of the screen.
  wincmd K
  " Set the window height to 5.
  5wincmd _
  " Switch back to working window.
  wincmd p
endfunction

autocmd User IcmLocationOpened call s:CustomizeIcmLocationWindow()

The IcmQuickFixOpened autocommand

This User autocommand is fired when iCM opens the quickfix window in response to the GoTo* and RefactorRename subcommands. By default, the quickfix window is opened to full width at the bottom of the screen and its height is set to fit all entries. This behavior can be overridden by using the IcmQuickFixOpened autocommand which is triggered while the cursor is in the quickfix window. For instance:

function! s:CustomizeIcmQuickFixWindow()
  " Move the window to the top of the screen.
  wincmd K
  " Set the window height to 5.
  5wincmd _
endfunction

autocmd User IcmQuickFixOpened call s:CustomizeIcmQuickFixWindow()

Options

All options have reasonable defaults so if the plug-in works after installation you don't need to change any options. These options can be configured in your vimrc script by including a line like this:

let g:icm_min_num_of_chars_for_completion = 1

Note that after changing an option in your vimrc script you have to restart Vim for the changes to take effect.

The g:icm_min_num_of_chars_for_completion option

This option controls the number of characters the user needs to type before identifier-based completion suggestions are triggered. For example, if the option is set to 2, then when the user types a second alphanumeric character after a whitespace character, completion suggestions will be triggered. This option is NOT used for semantic completion.

Setting this option to a high number like 99 effectively turns off the identifier completion engine and just leaves the semantic engine.

Default: 2

let g:icm_min_num_of_chars_for_completion = 2

The g:icm_min_num_identifier_candidate_chars option

This option controls the minimum number of characters that a completion candidate coming from the identifier completer must have to be shown in the popup menu.

A special value of 0 means there is no limit.

NOTE: This option only applies to the identifier completer; it has no effect on the various semantic completers.

Default: 0

let g:icm_min_num_identifier_candidate_chars = 0

The g:icm_auto_trigger option

When set to 0, this option turns off iCM's identifier completer (the as-you-type popup) and the semantic triggers (the popup you'd get after typing . or -> in say C++). You can still force semantic completion with the <C-Space> shortcut.

If you want to just turn off the identifier completer but keep the semantic triggers, you should set g:icm_min_num_of_chars_for_completion to a high number like 99.

Default: 1

let g:icm_auto_trigger = 1

The g:icm_filetype_whitelist option

This option controls for which Vim filetypes (see :h filetype) should iCM be turned on. The option value should be a Vim dictionary with keys being filetype strings (like python, cpp etc) and values being unimportant (the dictionary is used like a hash set, meaning that only the keys matter).

The * key is special and matches all filetypes. By default, the whitelist contains only this * key.

iCM also has a g:icm_filetype_blacklist option that lists filetypes for which iCM shouldn't be turned on. iCM will work only in filetypes that both the whitelist and the blacklist allow (the blacklist "allows" a filetype by not having it as a key).

For example, let's assume you want iCM to work in files with the cpp filetype. The filetype should then be present in the whitelist either directly (cpp key in the whitelist) or indirectly through the special * key. It should not be present in the blacklist.

Filetypes that are blocked by the either of the lists will be completely ignored by iCM, meaning that neither the identifier-based completion engine nor the semantic engine will operate in them.

You can get the filetype of the current file in Vim with :set ft?.

Default: {'swift' : 1}

let g:icm_filetype_whitelist = { 'swift': 1 }

The g:icm_filetype_blacklist option

This option controls for which Vim filetypes (see :h filetype) should iCM be turned off. The option value should be a Vim dictionary with keys being filetype strings (like python, cpp etc) and values being unimportant (the dictionary is used like a hash set, meaning that only the keys matter).

See the g:icm_filetype_whitelist option for more details on how this works.

Default: [see next line]

let g:icm_filetype_blacklist = {
      \ 'tagbar' : 1,
      \ 'qf' : 1,
      \ 'notes' : 1,
      \ 'markdown' : 1,
      \ 'unite' : 1,
      \ 'text' : 1,
      \ 'vimwiki' : 1,
      \ 'pandoc' : 1,
      \ 'infolog' : 1,
      \ 'mail' : 1
      \}

The g:icm_filetype_specific_completion_to_disable option

This option controls for which Vim filetypes (see :h filetype) should the iCM semantic completion engine be turned off. The option value should be a Vim dictionary with keys being filetype strings (like python, cpp etc) and values being unimportant (the dictionary is used like a hash set, meaning that only the keys matter). The listed filetypes will be ignored by the iCM semantic completion engine, but the identifier-based completion engine will still trigger in files of those filetypes.

Note that even if semantic completion is not turned off for a specific filetype, you will not get semantic completion if the semantic engine does not support that filetype.

You can get the filetype of the current file in Vim with :set ft?.

Default: [see next line]

let g:icm_filetype_specific_completion_to_disable = {
      \ 'gitcommit': 1
      \}

The g:icm_show_diagnostics_ui option

When set, this option turns on iCM's diagnostic display features. See the Diagnostic display section in the User Manual for more details.

Specific parts of the diagnostics UI (like the gutter signs, text highlighting, diagnostic echo and auto location list population) can be individually turned on or off. See the other options below for details.

When set, this option also makes iCM remove all Syntastic checkers set for the swift filetype since this would conflict with iCM's own diagnostics UI.

Unset to use with Syntastic diagnostic checkers.

Default: 1

let g:icm_show_diagnostics_ui = 1

The g:icm_error_symbol option

iCM will use the value of this option as the symbol for errors in the Vim gutter.

This option is part of the Syntastic compatibility layer; if the option is not set, iCM will fall back to the value of the g:syntastic_error_symbol option before using this option's default.

Default: >>

let g:icm_error_symbol = '>>'

The g:icm_warning_symbol option

iCM will use the value of this option as the symbol for warnings in the Vim gutter.

This option is part of the Syntastic compatibility layer; if the option is not set, iCM will fall back to the value of the g:syntastic_warning_symbol option before using this option's default.

Default: >>

let g:icm_warning_symbol = '>>'

The g:icm_enable_diagnostic_signs option

When this option is set, iCM will put icons in Vim's gutter on lines that have a diagnostic set. Turning this off will also turn off the IcmErrorLine and IcmWarningLine highlighting.

This option is part of the Syntastic compatibility layer; if the option is not set, iCM will fall back to the value of the g:syntastic_enable_signs option before using this option's default.

Default: 1

let g:icm_enable_diagnostic_signs = 1

The g:icm_enable_diagnostic_highlighting option

When this option is set, iCM will highlight regions of text that are related to the diagnostic that is present on a line, if any.

This option is part of the Syntastic compatibility layer; if the option is not set, iCM will fall back to the value of the g:syntastic_enable_highlighting option before using this option's default.

Default: 1

let g:icm_enable_diagnostic_highlighting = 1

The g:icm_echo_current_diagnostic option

When this option is set, iCM will echo the text of the diagnostic present on the current line when you move your cursor to that line. If a FixIt is available for the current diagnostic, then (FixIt) is appended.

This option is part of the Syntastic compatibility layer; if the option is not set, iCM will fall back to the value of the g:syntastic_echo_current_error option before using this option's default.

Default: 1

let g:icm_echo_current_diagnostic = 1

The g:icm_filter_diagnostics option

This option controls which diagnostics will be rendered by iCM. This option holds a dictionary of key-values, where the keys are Vim's filetype strings delimited by commas and values are dictionaries describing the filter.

A filter is a dictionary of key-values, where the keys are the type of filter, and the value is a list of arguments to that filter. In the case of just a single item in the list, you may omit the brackets and just provide the argument directly. If any filter matches a diagnostic, it will be dropped and iCM will not render it.

The following filter types are supported:

NOTE: The regex syntax is NOT Vim's, it's Python's.

Default: {}

let g:icm_filter_diagnostics = {
  \ "java": {
  \      "regex": [ ".*taco.*", ... ],
  \      "level": "error",
  \      ...
  \    }
  \ }

The g:icm_always_populate_location_list option

When this option is set, iCM will populate the location list automatically every time it gets new diagnostic data. This option is off by default so as not to interfere with other data you might have placed in the location list.

See :help location-list in Vim to learn more about the location list.

This option is part of the Syntastic compatibility layer; if the option is not set, iCM will fall back to the value of the g:syntastic_always_populate_loc_list option before using this option's default.

Default: 0

let g:icm_always_populate_location_list = 0

The g:icm_open_loclist_on_ycm_diags option

When this option is set, :IcmDiags will automatically open the location list after forcing a compilation and filling the list with diagnostic data.

See :help location-list in Vim to learn more about the location list.

Default: 1

let g:icm_open_loclist_on_ycm_diags = 1

The g:icm_complete_in_comments option

When this option is set to 1, iCM will show the completion menu even when typing inside comments.

Default: 0

let g:icm_complete_in_comments = 0

The g:icm_complete_in_strings option

When this option is set to 1, iCM will show the completion menu even when typing inside strings.

Default: 1

let g:icm_complete_in_strings = 1

The g:icm_collect_identifiers_from_comments_and_strings option

When this option is set to 1, iCM's identifier completer will also collect identifiers from strings and comments. Otherwise, the text in comments and strings will be ignored.

Default: 0

let g:icm_collect_identifiers_from_comments_and_strings = 0

The g:icm_collect_identifiers_from_tags_files option

When this option is set to 1, iCM's identifier completer will also collect identifiers from tags files. The list of tags files to examine is retrieved from the tagfiles() Vim function which examines the tags Vim option. See :h 'tags' for details.

iCM will re-index your tags files if it detects that they have been modified.

The only supported tag format is the Exuberant Ctags format. The format from "plain" ctags is NOT supported. Ctags needs to be called with the --fields=+l option (that's a lowercase L, not a one) because iCM needs the language:<lang> field in the tags output.

See the FAQ for pointers if iCM does not appear to read your tag files.

This option is off by default because it makes Vim slower if your tags are on a network directory.

Default: 0

let g:icm_collect_identifiers_from_tags_files = 0

The g:icm_seed_identifiers_with_syntax option

When this option is set to 1, iCM's identifier completer will seed its identifier database with the keywords of the programming language you're writing.

Since the keywords are extracted from the Vim syntax file for the filetype, all keywords may not be collected, depending on how the syntax file was written. Usually at least 95% of the keywords are successfully extracted.

Default: 0

let g:icm_seed_identifiers_with_syntax = 0

The g:icm_server_python_interpreter option

iCM will by default search for an appropriate Python interpreter on your system. You can use this option to override that behavior and force the use of a specific interpreter of your choosing.

NOTE: This interpreter is only used for the ycmd server. The iCM client running inside Vim always uses the Python interpreter that's embedded inside Vim.

Default: ''

let g:icm_server_python_interpreter = ''

The g:icm_keep_logfiles option

When this option is set to 1, iCM and the ycmd completion server will keep the logfiles around after shutting down (they are deleted on shutdown by default).

To see where the logfiles are, call :IcmDebugInfo.

Default: 0

let g:icm_keep_logfiles = 0

The g:icm_log_level option

The logging level that iCM and the ycmd completion server use. Valid values are the following, from most verbose to least verbose:

Note that debug is very verbose.

Default: info

let g:icm_log_level = 'info'

The g:icm_add_preview_to_completeopt option

When this option is set to 1, iCM will add the preview string to Vim's completeopt option (see :h completeopt). If your completeopt option already has preview set, there will be no effect. You can see the current state of your completeopt setting with :set completeopt? (yes, the question mark is important).

When preview is present in completeopt, iCM will use the preview window at the top of the file to store detailed information about the current completion candidate (but only if the candidate came from the semantic engine). For instance, it would show the full function prototype and all the function overloads in the window if the current completion is a function name.

Default: 0

let g:icm_add_preview_to_completeopt = 0

The g:icm_autoclose_preview_window_after_completion option

When this option is set to 1, iCM will auto-close the preview window after the user accepts the offered completion string. If there is no preview window triggered because there is no preview string in completeopt, this option is irrelevant. See the g:icm_add_preview_to_completeopt option for more details.

Default: 0

let g:icm_autoclose_preview_window_after_completion = 0

The g:icm_autoclose_preview_window_after_insertion option

When this option is set to 1, iCM will auto-close the preview window after the user leaves insert mode. This option is irrelevant if g:icm_autoclose_preview_window_after_completion is set or if no preview window is triggered. See the g:icm_add_preview_to_completeopt option for more details.

Default: 0

let g:icm_autoclose_preview_window_after_insertion = 0

The g:icm_max_diagnostics_to_display option

This option controls the maximum number of diagnostics shown to the user when errors or warnings are detected in the file.

Default: 30

let g:icm_max_diagnostics_to_display = 30

The g:icm_key_list_select_completion option

This option controls the key mappings used to select the first completion string. Invoking any of them repeatedly cycles forward through the completion list.

Some users like adding <Enter> to this list.

Default: ['<TAB>', '<Down>']

let g:icm_key_list_select_completion = ['<TAB>', '<Down>']

The g:icm_key_list_previous_completion option

This option controls the key mappings used to select the previous completion string. Invoking any of them repeatedly cycles backwards through the completion list.

Note that one of the defaults is <S-TAB> which means Shift-TAB. That mapping will probably only work in GUI Vim (Gvim or MacVim) and not in plain console Vim because the terminal usually does not forward modifier key combinations to Vim.

Default: ['<S-TAB>', '<Up>']

let g:icm_key_list_previous_completion = ['<S-TAB>', '<Up>']

The g:icm_key_invoke_completion option

This option controls the key mapping used to invoke the completion menu for semantic completion. By default, semantic completion is trigged automatically after typing ., -> and :: in insert mode (if semantic completion support has been compiled in). This key mapping can be used to trigger semantic completion anywhere. Useful for searching for top-level functions and classes.

Console Vim (not Gvim or MacVim) passes <Nul> to Vim when the user types <C-Space> so iCM will make sure that <Nul> is used in the map command when you're editing in console Vim, and <C-Space> in GUI Vim. This means that you can just press <C-Space> in both console and GUI Vim and iCM will do the right thing.

Setting this option to an empty string will make sure no mapping is created.

Default: <C-Space>

let g:icm_key_invoke_completion = '<C-Space>'

The g:icm_key_detailed_diagnostics option

This option controls the key mapping used to show the full diagnostic text when the user's cursor is on the line with the diagnostic. It basically calls :IcmShowDetailedDiagnostic.

Setting this option to an empty string will make sure no mapping is created.

Default: <leader>d

let g:icm_key_detailed_diagnostics = '<leader>d'

The g:icm_global_ycm_extra_conf option

Normally, iCM searches for a .ycm_extra_conf.py file for compilation flags (see the User Guide for more details on how this works). This option specifies a fallback path to a config file which is used if no .ycm_extra_conf.py is found.

You can place such a global file anywhere in your filesystem.

Default: ''

let g:icm_global_ycm_extra_conf = ''

The g:icm_confirm_extra_conf option

When this option is set to 1 iCM will ask once per .ycm_extra_conf.py file if it is safe to be loaded. This is to prevent execution of malicious code from a .ycm_extra_conf.py file you didn't write.

To selectively get iCM to ask/not ask about loading certain .ycm_extra_conf.py files, see the g:icm_extra_conf_globlist option.

Default: 1

let g:icm_confirm_extra_conf = 1

The g:icm_extra_conf_globlist option

This option is a list that may contain several globbing patterns. If a pattern starts with a ! all .ycm_extra_conf.py files matching that pattern will be blacklisted, that is they won't be loaded and no confirmation dialog will be shown. If a pattern does not start with a ! all files matching that pattern will be whitelisted. Note that this option is not used when confirmation is disabled using g:icm_confirm_extra_conf and that items earlier in the list will take precedence over the later ones.

Rules:

Example:

let g:icm_extra_conf_globlist = ['~/dev/*','!~/*']

NOTE: The glob pattern is first expanded with Python's os.path.expanduser() and then resolved with os.path.abspath() before being matched against the filename.

Default: []

let g:icm_extra_conf_globlist = []

The g:icm_filepath_completion_use_working_dir option

By default, iCM's filepath completion will interpret relative paths like ../ as being relative to the folder of the file of the currently active buffer. Setting this option will force iCM to always interpret relative paths as being relative to Vim's current working directory.

Default: 0

let g:icm_filepath_completion_use_working_dir = 0

The g:icm_semantic_triggers option

This option controls the character-based triggers for the various semantic completion engines. The option holds a dictionary of key-values, where the keys are Vim's filetype strings delimited by commas and values are lists of strings, where the strings are the triggers.

Setting key-value pairs on the dictionary adds semantic triggers to the internal default set (listed below). You cannot remove the default triggers, only add new ones.

A "trigger" is a sequence of one or more characters that trigger semantic completion when typed. For instance, C++ (cpp filetype) has . listed as a trigger. So when the user types foo., the semantic engine will trigger and serve foo's list of member functions and variables. Since C++ also has -> listed as a trigger, the same thing would happen when the user typed foo->.

It's also possible to use a regular expression as a trigger. You have to prefix your trigger with re! to signify it's a regex trigger. For instance, re!\w+\. would only trigger after the \w+\. regex matches.

NOTE: The regex syntax is NOT Vim's, it's Python's.

Default: [see next line]

let g:icm_semantic_triggers =  {
  \   'swift' : ['.', '[_a-zA-Z'],
  \ }

The g:icm_cache_omnifunc option

Some omnicompletion engines do not work well with the iCM cache—in particular, they might not produce all possible results for a given prefix. By unsetting this option you can ensure that the omnicompletion engine is re-queried on every keypress. That will ensure all completions will be presented, but might cause stuttering and lagginess if the omnifunc is slow.

Default: 1

let g:icm_cache_omnifunc = 1

The g:icm_use_ultisnips_completer option

By default, iCM will query the UltiSnips plugin for possible completions of snippet triggers. This option can turn that behavior off.

Default: 1

let g:icm_use_ultisnips_completer = 1

The g:icm_goto_buffer_command option

Defines where GoTo* commands result should be opened. Can take one of the following values: [ 'same-buffer', 'horizontal-split', 'vertical-split', 'new-tab', 'new-or-existing-tab' ] If this option is set to the 'same-buffer' but current buffer can not be switched (when buffer is modified and nohidden option is set), then result will be opened in horizontal split.

Default: 'same-buffer'

let g:icm_goto_buffer_command = 'same-buffer'

The g:icm_disable_for_files_larger_than_kb option

Defines the max size (in Kb) for a file to be considered for completion. If this option is set to 0 then no check is made on the size of the file you're opening.

Default: 1000

let g:icm_disable_for_files_larger_than_kb = 1000

The g:icm_python_binary_path option

TODO:jerry Remove ( I don't think we need this )

This option specifies the Python interpreter to use to run the [jedi][] completion library. Specify the Python interpreter to use to get completions. By default the Python under which ycmd runs is used (ycmd runs on Python 2.6, 2.7 or 3.3+).

Default: ''

let g:icm_python_binary_path = 'python'

NOTE: the settings above will make iCM use the first python executable found through the PATH.

FAQ

I used to be able to import vim in .ycm_extra_conf.py, but now can't

iCM was rewritten to use a client-server architecture where most of the logic is in the ycmd server. So the magic vim module you could have previously imported in your .ycm_extra_conf.py files doesn't exist anymore.

To be fair, importing the magic vim module in extra conf files was never supported in the first place; it only ever worked by accident and was never a part of the extra conf API.

But fear not, you should be able to tweak your extra conf files to continue working by using the g:icm_extra_conf_vim_data option. See the docs on that option for details.

I get ImportError exceptions that mention PyInit_ycm_core or initycm_core

These errors are caused by building the iCM native libraries for Python 2 and trying to load them into a Python 3 process (or the other way around).

For instance, if building for Python 2 but loading in Python 3:

ImportError: dynamic module does not define init function (PyInit_ycm_core)

If building for Python 3 but loading in Python 2:

ImportError: dynamic module does not define init function (initycm_core)

Setting the g:icm_server_python_interpreter option to force the use of a specific Python interpreter for ycmd is usually the easiest way to solve the problem. Common values for that option are /usr/bin/python and /usr/bin/python3.

I get a linker warning regarding libpython on Mac when compiling iCM

If the warning is ld: warning: path '/usr/lib/libpython2.7.dylib' following -L not a directory, then feel free to ignore it; it's caused by a limitation of CMake and is not an issue. Everything should still work fine.

I get a weird window at the top of my file when I use the semantic engine

This is Vim's preview window. Vim uses it to show you extra information about something if such information is available. iCM provides Vim with such extra information. For instance, when you select a function in the completion list, the preview window will hold that function's prototype and the prototypes of any overloads of the function. It will stay there after you select the completion so that you can use the information about the parameters and their types to write the function call.

If you would like this window to auto-close after you select a completion string, set the g:icm_autoclose_preview_window_after_completion option to 1 in your vimrc file. Similarly, the g:icm_autoclose_preview_window_after_insertion option can be set to close the preview window after leaving insert mode.

If you don't want this window to ever show up, add set completeopt-=preview to your vimrc. Also make sure that the g:icm_add_preview_to_completeopt option is set to 0.

It appears that iCM is not working

In Vim, run :messages and carefully read the output. iCM will echo messages to the message log if it encounters problems. It's likely you misconfigured something and iCM is complaining about it.

Also, you may want to run the :IcmDebugInfo command; it will make iCM spew out various debugging information, including the iCM and ycmd logfile paths and the compile flags for the current file if the file is a Swift file and you have compiled in Swift support. Logfiles can be opened in the editor using the :IcmToggleLogs command.

Sometimes it takes much longer to get semantic completions than normal

This means that the Swift language facilities (which iCM uses for Swift semantic completion) failed to pre-compile your file's preamble. In other words, there was an error compiling some of the source code you pulled in through your header files. I suggest calling the :IcmDiags command to see what they were.

Bottom line, if Swift can't pre-compile your file's because there were errors in it, you're going to get slow completions because there's no AST cache.

iCM auto-inserts completion strings I don't want!

This means you probably have some mappings that interfere with iCM's internal ones. Make sure you don't have something mapped to <C-p>, <C-x> or <C-u> (in insert mode).

iCM never selects something for you; it just shows you a menu and the user has to explicitly select something. If something is being selected automatically, this means there's a bug or a misconfiguration somewhere.

I get a E227: mapping already exists for <blah> error when I start Vim

This means that iCM tried to set up a key mapping but failed because you already had something mapped to that key combination. The <blah> part of the message will tell you what was the key combination that failed.

Look in the Options section and see if any of the default mappings conflict with your own. Then change that option value to something else so that the conflict goes away.

I get 'GLIBC_2.XX' not found (required by libclang.so) when starting Vim

Your system is too old for the precompiled binaries from llvm.org. Compile Clang on your machine and then link against the libclang.so you just produced. See the full installation guide for help.

I'm trying to use a Homebrew Vim with iCM and I'm getting segfaults

Something (I don't know what) is wrong with the way that Homebrew configures and builds Vim. I recommend using MacVim. Even if you don't like the MacVim GUI, you can use the Vim binary that is inside the MacVim.app package (it's MacVim.app/Contents/MacOS/Vim) and get the Vim console experience.

I have a Homebrew Python and/or MacVim; can't compile/SIGABRT when starting

You should probably run brew rm python; brew install python to get the latest fixes that should make iCM work with such a configuration. Also rebuild Macvim then. If you still get problems with this, see issue #18 for suggestions.

I get LONG_BIT definition appears wrong for platform when compiling

Look at the output of your CMake call. There should be a line in it like the following (with .dylib in place of .so on a Mac):

-- Found PythonLibs: /usr/lib/libpython2.7.so (Required is at least version "2.5")

That would be the correct output. An example of incorrect output would be the following:

-- Found PythonLibs: /usr/lib/libpython2.7.so (found suitable version "2.5.1", minimum required is "2.5")

Notice how there's an extra bit of output there, the found suitable version "<version>" part, where <version> is not the same as the version of the dynamic library. In the example shown, the library is version 2.7 but the second string is version 2.5.1.

This means that CMake found one version of Python headers and a different version for the library. This is wrong. It can happen when you have multiple versions of Python installed on your machine.

You should probably add the following flags to your cmake call (again, dylib instead of so on a Mac):

-DPYTHON_INCLUDE_DIR=/usr/include/python2.7 -DPYTHON_LIBRARY=/usr/lib/libpython2.7.so

This will force the paths to the Python include directory and the Python library to use. You may need to set these flags to something else, but you need to make sure you use the same version of Python that your Vim binary is built against, which is highly likely to be the system's default Python.

I get libpython2.7.a [...] relocation R_X86_64_32 when compiling

The error is usually encountered when compiling iCM on Centos or RHEL. The full error looks something like the following:

/usr/bin/ld: /usr/local/lib/libpython2.7.a(abstract.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC

It's possible to get a slightly different error that's similar to the one above. Here's the problem and how you solve it:

Your libpython2.7.a was not compiled with -fPIC so it can't be linked into ycm_core.so. Use the -DPYTHON_LIBRARY= CMake flag to point it to a .so version of libpython on your machine (for instance, -DPYTHON_LIBRARY=/usr/lib/libpython2.7.so). Naturally, this means you'll have to go through the full installation guide by hand.

I get Vim: Caught deadly signal SEGV on Vim startup

This can happen on some Linux distros. If you encounter this situation, run Vim under gdb. You'll probably see something like this in the output when Vim crashes:

undefined symbol: clang_CompileCommands_dispose

This means that Vim is trying to load a libclang.so that is too old. You need at least a 3.9 libclang. Just go through the installation guide and make sure you are using a correct libclang.so. We recommend downloading prebuilt binaries from llvm.org.

I get Fatal Python error: PyThreadState_Get: no current thread on startup

This is caused by linking a static version of libpython into ycmd's ycm_core.so. This leads to multiple copies of the python interpreter loaded when python loads ycmd_core.so and this messes up python's global state. The details aren't important.

The solution is that the version of Python linked and run against must be built with either --enable-shared or --enable-framework (on OS X). This is achieved as follows (NOTE: for Mac, replace --enable-shared with --enable-framework):

install.py says python must be compiled with --enable-framework. Wat?

See the previous answer for how to ensure your python is built to support dynamic modules.

iCM does not read identifiers from my tags files

First, put let g:icm_collect_identifiers_from_tags_files = 1 in your vimrc.

Make sure you are using Exuberant Ctags to produce your tags files since the only supported tag format is the Exuberant Ctags format. The format from "plain" ctags is NOT supported. The output of ctags --version should list "Exuberant Ctags".

Ctags needs to be called with the --fields=+l (that's a lowercase L, not a one) option because iCM needs the language:<lang> field in the tags output.

NOTE: Exuberant Ctags by default sets language tag for *.h files as C++. If you have C (not C++) project, consider giving parameter --langmap=c:.c.h to ctags to see tags from *.h files.

NOTE: Mac OS X comes with "plain" ctags installed by default. brew install ctags will get you the Exuberant Ctags version.

Also make sure that your Vim tags option is set correctly. See :h 'tags' for details. If you want to see which tag files iCM will read for a given buffer, run :echo tagfiles() with the relevant buffer active. Note that that function will only list tag files that already exist.

CTRL-U in insert mode does not work

iCM keeps you in a completefunc completion mode when you're typing in insert mode and Vim disables <C-U> in completion mode as a "feature." Sadly there's nothing I can do about this.

iCM conflicts with UltiSnips TAB key usage

iCM comes with support for UltiSnips (snippet suggestions in the popup menu), but you'll have to change the UltiSnips mappings. See :h UltiSnips-triggers in Vim for details. You'll probably want to change some/all of the following options:

g:UltiSnipsExpandTrigger
g:UltiSnipsJumpForwardTrigger
g:UltiSnipsJumpBackwardTrigger

Snippets added with :UltiSnipsAddFiletypes do not appear in the popup menu

For efficiency, iCM only fetches UltiSnips snippets in specific scenarios like visiting a buffer or setting its filetype. You can force iCM to retrieve them by manually triggering the FileType autocommand:

:doautocmd FileType

Why isn't iCM just written in plain VimScript, FFS?

Because of the identifier completion engine and subsequence-based filtering. Let's say you have many dozens of files open in a single Vim instance (I often do); the identifier-based engine then needs to store thousands (if not tens of thousands) of identifiers in its internal data-structures. When the user types, iCM needs to perform subsequence-based filtering on all of those identifiers (every single one!) in less than 10 milliseconds.

I'm sorry, but that level of performance is just plain impossible to achieve with VimScript. I've tried, and the language is just too slow. No, you can't get acceptable performance even if you limit yourself to just the identifiers in the current file and simple prefix-based filtering.

Why does iCM demand such a recent version of Vim?

iCM needs a version of Vim with the timers feature to achieve full asynchronicity. This feature is available since Vim 7.4.1578.

Nasty bugs happen if I have the vim-autoclose plugin installed

Use the delimitMate plugin instead. It does the same thing without conflicting with iCM.

I get an internal compiler error when installing

This can be a problem on virtual servers with limited memory. A possible solution is to add more swap memory. A more practical solution would be to force the build script to run only one compile job at a time. You can do this by setting the iCM_CORES environment variable to 1. Example:

iCM_CORES=1 ./install.py --clang-completer

I get weird errors when I press Ctrl-C in Vim

Never use Ctrl-C in Vim.

Using Ctrl-C to exit insert mode in Vim is a bad idea. The main issue here is that Ctrl-C in Vim doesn't just leave insert mode, it leaves it without triggering InsertLeave autocommands (as per Vim docs). This is a bad idea and is likely to break many other things and not just iCM.

Bottom line, if you use Ctrl-C to exit insert mode in Vim, you're gonna have a bad time.

If pressing <esc> is too annoying (agreed, it is), we suggest mapping it to something more convenient. On a QWERTY keyboard, a good pick for the <esc> map is inoremap jk <Esc>. This is right on the home row, it's an incredibly rare digraph in English and if you ever need to type those two chars in sequence in insert mode, you just type j, then wait 500ms, then type k.

When I start vim I get a runtime error saying R6034 An application has made an attempt to load the C runtime library incorrectly.

CMake and other things seem to screw up the PATH with their own msvcrXX.dll versions. Add the following to the very top of your vimrc to remove these entries from the path.

python << EOF
import os
import re
path = os.environ['PATH'].split(';')

def contains_msvcr_lib(folder):
    try:
        for item in os.listdir(folder):
            if re.match(r'msvcr\d+\.dll', item):
                return True
    except:
        pass
    return False

path = [folder for folder in path if not contains_msvcr_lib(folder)]
os.environ['PATH'] = ';'.join(path)
EOF

I hear that iCM only supports Python 2, is that true?

No. Both the Vim client and the ycmd server run on Python 2 or 3. If you work on a Python 3 project, you may need to set g:icm_python_binary_path to the Python interpreter you use for your project to get completions for that version of Python.

On Windows I get E887: Sorry, this command is disabled, the Python's site module could not be loaded

If you are running vim on Windows with Python 2.7.11, this is likely caused by a bug. Follow this workaround or use a different version (Python 2.7.12 does not suffer from the bug).

I can't complete python packages in a virtual environment.

This means that the Python used to run [JediHTTP][] is not the Python of the virtual environment you're in. To resolve this you either set g:icm_python_binary_path to the absolute path of the Python binary in your virtual environment or since virtual environment will put that Python executable first in your PATH when the virtual environment is active then if you set g:icm_python_binary_path to just 'python' it will be found as the first Python and used to run [JediHTTP][].

I want to defer loading of iCompleteMe until after Vim finishes booting

In recent versions of Vim, you can install iCM in a folder under ~/.vim/pack/*/opt and then load it once the user is idle via an autocommand:

augroup load_ycm
  autocmd!
  autocmd CursorHold, CursorHoldI * :packadd iCompleteMe
                                \ | autocmd! load_ycm
augroup END

iCM does not shut down when I quit Vim

iCM relies on the VimLeave event to shut down the ycmd server. Some plugins prevent this event from triggering by exiting Vim through an autocommand without using the nested keyword (see :h autocmd-nested). One of these plugins is vim-nerdtree-tabs. You should identify which plugin is responsible for the issue and report it to the plugin author. Note that when this happens, ycmd will automatically shut itself down after 30 minutes.

Contributor Code of Conduct

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.

Contact

If you have bug reports or feature suggestions, please use the issue tracker.

The author's homepage is http://jerrymarino.com.

License

This software is licensed under the GPL v3 license. © 2015-2017 YouCompleteMe contributors © 2017 Jerry Marino