YouCompleteMe: a code-completion engine for Vim =============================================== Help, Advice, Support --------------------- Looking for help, advice, or support? Having problems getting YCM to work? First carefully read the for your OS. We recommend you use the supplied install.py - the "full" installation guide is for rare, advanced use cases and most users should use install.py.
Tools
Tools
No tool list yet. Remote servers get one after the first health check.
Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.
Does YouCompleteMe need an API key?
No required environment variable is listed on this record.
What transport does YouCompleteMe use?
YouCompleteMe runs locally over stdio.
When was YouCompleteMe last checked?
Last checked 2026-11-10. YouCompleteMe: a code-completion engine for Vim =============================================== Help, Advice, Support --------------------- Looking for help, advice, or support? Having problems getting YCM to work? First carefully read the for your OS. We recommend you use the supplied install.py - the "full" installation guide is for rare, advanced use cases and most users should use install.py.
From the publisher
Documentation
YouCompleteMe: a code-completion engine for Vim
Help, Advice, Support
Looking for help, advice, or support? Having problems getting YCM to work?
First carefully read the installation instructions for your OS.
We recommend you use the supplied install.py - the "full" installation guide
is for rare, advanced use cases and most users should use install.py.
If the server isn't starting and you're getting a "YouCompleteMe unavailable"
error, check the [Troubleshooting][wiki-troubleshooting] guide.
Next, check the User Guide section on the semantic completer that
you are using. For C/C++/Objective-C/Objective-C++/CUDA, you must read this
section.
Key features
01. A code-completion engine for Vim
02. YouCompleteMe: a code-completion engine for Vim =============================================== Help, Advice, Support --------------------- Looking for help, advice, or support? Having problems getting YCM to work? First carefully read the for your OS
03. We recommend you use the supplied install
04. py - the "full" installation guide is for rare, advanced use cases and most users should use install
05. YouCompleteMe: a code-completion engine for Vim
Finally, check the [FAQ][wiki-faq].
If, after reading the installation and user guides, and checking the FAQ, you're
still having trouble, check the contacts section below for how to
get in touch.
Please do NOT go to #vim on Freenode for support. Please contact the
YouCompleteMe maintainers directly using the contact details below.
Vundle
Please note that the below instructions suggest using Vundle. Currently there
are problems with Vundle, so here are some alternative instructions using Vim packages.
YouCompleteMe is a fast, as-you-type, fuzzy-search code completion,
comprehension and refactoring engine for [Vim][].
It has several completion engines built-in and supports any protocol-compliant
Language Server, so can work with practically any language. YouCompleteMe
contains:
an identifier-based engine that works with every programming language,
a powerful [clangd][]-based engine that provides native semantic code
completion for C/C++/Objective-C/Objective-C++/CUDA (from now on referred to
as "the C-family languages"),
a [Jedi][]-based completion engine for Python 2 and 3,
an [OmniSharp-Roslyn][]-based completion engine for C#,
a [Gopls][]-based completion engine for Go,
a [TSServer][]-based completion engine for JavaScript and TypeScript,
a [rust-analyzer][]-based completion engine for Rust,
and an omnifunc-based completer that uses data from Vim's omnicomplete system
to provide semantic completions for many other languages (Ruby, PHP, etc.).
Here's an explanation of what happened in the last GIF demo above.
First, realize that no keyboard shortcuts had to be pressed to get the list
of completion candidates at any point in the demo. The user just types and the
suggestions pop up by themselves. If the user doesn't find the completion
suggestions relevant and/or just wants to type, they can do so; the completion
engine will not interfere.
When the user sees a useful completion string being offered, they press the TAB
key to accept it. This inserts the completion string. Repeated presses of the
TAB key cycle through the offered completions.
If the offered completions are not relevant enough, the user can continue typing
to further filter out unwanted completions.
A critical thing to notice is that the completion filtering is NOT based on
the input being a string prefix of the completion (but that works too). The
input needs to be a [subsequence][] match of a completion. This is a fancy way
of saying that any input characters need to be present in a completion string in
the order in which they appear in the input. So abc is a subsequence of
xaybgc, but not of xbyxaxxc. After the filter, a complicated sorting system
ranks the completion strings so that the most relevant ones rise to the top of
the menu (so you usually need to press TAB just once).
All of the above works with any programming language because of the
identifier-based completion engine. It 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).
The demo also shows the semantic engine in use. When the user presses ., ->
or :: while typing in insert mode (for C++; different triggers are used for
other languages), the semantic engine is triggered (it can also be triggered
with a keyboard shortcut; see the rest of the docs).
The last thing that you can see in the demo is YCM's diagnostic display features
(the little red X that shows up in the left gutter; inspired by [Syntastic][])
if you are editing a C-family file. As the completer engine compiles your file
and detects warnings or errors, they will be presented in various ways. You
don't need to save your file or press any keyboard shortcut to trigger this, it
"just happens" in the background.
And that's not all...
YCM might be the only Vim completion engine with the correct Unicode support.
Though we do assume UTF-8 everywhere.
For Neovim users, our policy is to require the latest released version.
Currently, Neovim 0.5.0 is required. Please note that some features are not
available in Neovim, and Neovim is not officially supported.
Supported Python runtime
YCM has two components: A server and a client. Both the server and client
require Python 3.12 or later 3.x release.
For the Vim client, Vim must be, compiled with --enable-shared (or
--enable-framework on macOS). You can check if this is working with :py3 import sys; print( sys.version). It should say something like 3.12.0 (...).
For Neovim, you must have a python 3.12 runtime and the Neovim python
extensions. See Neovim's :help provider-python for how to set that up.
For the server, you must run the install.py script with a python 3.12 (or
later) runtime. Anaconda etc. are not supported. YCM will remember the runtime
you used to run install.py and will use that when launching the server, so if
you usually use anaconda, then make sure to use the full path to a real cpython3,
e.g. /usr/bin/python3 install.py --all etc.
Our policy is to support the python3 version that's available in the latest
Ubuntu LTS (similar to our Vim version policy). We don't increase the Python
runtime version without a reason, though. Typically, we do this when the current
python version we're using goes out of support. At that time we will typically
pick a version that will be supported for a number of years.
Supported Compilers
In order to provide the best possible performance and stability, ycmd has
updated its code to C++17. This requires a version bump of the minimum
supported compilers. The new requirements are:
Compiler
Current Min
GCC
8
Clang
7
MSVC
15.7 (VS 2017)
YCM requires CMake 3.13 or greater. If your CMake is too old, you may be able to
simply pip install --user cmake to get a really new version.
Individual completer requirements
When enabling language support for a particular language, there may be runtime
requirements, such as needing a very recent Java Development Kit for Java
support. In general, YCM is not in control of the required versions for the
downstream compilers, though we do our best to signal where we know them.
macOS
Quick start, installing all completers
Install YCM plugin via [Vundle][]
Install CMake, MacVim and Python 3; Note that the pre-installed macOS system
Vim is not supported (due to it having broken Python integration).
$ brew install cmake python go nodejs
Install mono from Mono Project (NOTE: on Intel Macs you
can also brew install mono. On arm Macs, you may require Rosetta)
For Java support you must install a JDK, one way to do this is with Homebrew:
Pre-installed macOS system Vim does not support Python 3. So you need to
install either a Vim that supports Python 3 OR [MacVim][] with
[Homebrew][brew]:
Option 1: Installing a Vim that supports Python 3
brew install vim
Option 2: Installing [MacVim][]
brew install macvim
Compile YCM.
For Intel and arm64 Macs, the bundled libclang/clangd work:
cd ~/.vim/bundle/YouCompleteMe
python3 install.py --all
If you have troubles with finding system frameworks or C++ standard library,
try using the homebrew llvm:
brew install llvm
cd ~/.vim/bundle/YouCompleteMe
python3 install.py --system-libclang --all
And edit your vimrc to add the following line to use the Homebrew llvm's
clangd:
" Use homebrew's clangd
let g:ycm_clangd_binary_path = trim(system('brew --prefix llvm')).'/bin/clangd'
These instructions (using install.py) are the quickest way to install
YouCompleteMe, however they may not work for everyone. If the following
instructions don't work for you, check out the full installation
guide.
A supported Vim version with Python 3 is required. [MacVim][] is a good option,
even if you only use the terminal. YCM won't work with the pre-installed Vim
from Apple as its Python support is broken. If you don't already use a Vim
that supports Python 3 or [MacVim][], install it with [Homebrew][brew]. Install
CMake as well:
brew install vim cmake
OR
brew install macvim cmake
Install YouCompleteMe with [Vundle][].
Remember: YCM is a plugin with a compiled component. If you update YCM
using Vundle and the ycm_core library APIs have changed (happens
rarely), YCM will notify you to recompile it. You should then rerun the install
process.
NOTE: If you want C-family 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)
Compiling YCM with semantic support for C-family languages through
clangd:
cd ~/.vim/bundle/YouCompleteMe
./install.py --clangd-completer
Compiling YCM without semantic support for C-family languages:
cd ~/.vim/bundle/YouCompleteMe
./install.py
The following additional language support options are available:
C# support: install by downloading the [Mono macOS package][mono-install-macos]
and add --cs-completer when calling install.py.
Go support: install [Go][go-install] and add --go-completer when calling
install.py.
JavaScript and TypeScript support: install [Node.js 18+ and npm][npm-install] and
add --ts-completer when calling install.py.
Rust support: add --rust-completer when calling install.py.
Java support: install [JDK 17][jdk-install] and add
--java-completer when calling install.py.
To simply compile with everything enabled, there's a --all flag. So, to
install with all language features, ensure xbuild, go, node and npm
tools are installed and in your PATH, then simply run:
cd ~/.vim/bundle/YouCompleteMe
./install.py --all
That's it. You're done. Refer to the User Guide section on how to use YCM.
Don't forget that if you want the C-family semantic completion engine to work,
you will need to provide the compilation flags for your project to YCM. It's all
in the User Guide.
YCM 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.
These instructions (using install.py) are the quickest way to install
YouCompleteMe, 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 a supported version of Vim with Python 3 support and a
supported compiler. The latest LTS of Ubuntu is the minimum platform for simple
installation. For earlier releases or other distributions, you may have to do
some work to acquire the dependencies.
If your Vim version is too old, you may need to [compile Vim from
source][vim-build] (don't worry, it's easy).
Install YouCompleteMe with [Vundle][].
Remember: YCM is a plugin with a compiled component. If you update YCM
using Vundle and the ycm_core library APIs have changed (which happens rarely), YCM
will notify you to recompile it. You should then rerun the installation process.
Install development tools, CMake, and Python headers:
Compiling YCM with semantic support for C-family languages through
clangd:
cd ~/.vim/bundle/YouCompleteMe
python3 install.py --clangd-completer
Compiling YCM without semantic support for C-family languages:
cd ~/.vim/bundle/YouCompleteMe
python3 install.py
The following additional language support options are available:
C# support: install [Mono][mono-install-linux] and add --cs-completer
when calling install.py.
Go support: install [Go][go-install] and add --go-completer when calling
install.py.
JavaScript and TypeScript support: install [Node.js 18+ and npm][npm-install] and
add --ts-completer when calling install.py.
Rust support: add --rust-completer when calling install.py.
Java support: install [JDK 17][jdk-install] and add
--java-completer when calling install.py.
To simply compile with everything enabled, there's a --all flag. So, to
install with all language features, ensure xbuild, go, node, and npm
tools are installed and in your PATH, then simply run:
cd ~/.vim/bundle/YouCompleteMe
python3 install.py --all
That's it. You're done. Refer to the User Guide section on how to use YCM.
Don't forget that if you want the C-family semantic completion engine to work,
you will need to provide the compilation flags for your project to YCM. It's all
in the User Guide.
YCM 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
NOTE: Windows support is deprecated and unmaintained. We will do our
best to keep it working, but we no longer test it in CI and there is a high
likelihood of breakages.
Quick start, installing all completers
Install YCM plugin via [Vundle][]
Install [Visual Studio Build Tools 2019][visual-studio-download]
These instructions (using install.py) are the quickest way to install
YouCompleteMe, 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 a supported Vim version with Python 3 support. You
can check the version and which Python is supported by typing :version inside
Vim. Look at the features included: +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 installers of 32-bit and 64-bit Vim with
Python 3 support][vim-win-download] are available.
Add the following line to your [vimrc][] if not already present.:
set encoding=utf-8
This option is required by YCM. Note that it does not prevent you from editing a
file in another encoding than UTF-8. You can do that by specifying [the ++enc
argument][++enc] to the :e command.
Install YouCompleteMe with [Vundle][].
Remember: YCM is a plugin with a compiled component. If you update YCM
using Vundle and the ycm_core library APIs have changed (happens
rarely), YCM will notify you to recompile it. You should then rerun the install
process.
Download and install the following software:
[Python 3][python-win-download]. Be sure to pick the version
corresponding to your Vim architecture. It is Windows x86 for a 32-bit Vim
and Windows x86-64 for a 64-bit Vim. We recommend installing Python 3.
Additionally, the version of Python you install must match up exactly with
the version of Python that Vim is looking for. Type :version and look at the
bottom of the page at the list of compiler flags. Look for flags that look
similar to -DDYNAMIC_PYTHON3_DLL=\"python36.dll\". This indicates
that Vim is looking for Python 3.6. You'll need one or the other installed,
matching the version number exactly.
[CMake][cmake-download]. Add CMake executable to the PATH environment
variable.
[Build Tools for Visual Studio 2019][visual-studio-download]. During setup,
select C++ build tools in Workloads.
Compiling YCM with semantic support for C-family languages through
clangd:
cd %USERPROFILE%/vimfiles/bundle/YouCompleteMe
python install.py --clangd-completer
Compiling YCM without semantic support for C-family languages:
cd %USERPROFILE%/vimfiles/bundle/YouCompleteMe
python install.py
The following additional language support options are available:
C# support: add --cs-completer when calling install.py.
Be sure that [the build utility msbuild is in your PATH][add-msbuild-to-path].
Go support: install [Go][go-install] and add --go-completer when calling
install.py.
JavaScript and TypeScript support: install [Node.js 18+ and npm][npm-install] and
add --ts-completer when calling install.py.
Rust support: add --rust-completer when calling install.py.
Java support: install [JDK 17][jdk-install] and add
--java-completer when calling install.py.
To simply compile with everything enabled, there's a --all flag. So, to
install with all language features, ensure msbuild, go, node and npm
tools are installed and in your PATH, then simply run:
cd %USERPROFILE%/vimfiles/bundle/YouCompleteMe
python install.py --all
You can specify the Microsoft Visual C++ (MSVC) version using the --msvc
option. YCM officially supports MSVC 15 (2017), MSVC 16 (Visual Studio 2019)
and MSVC 17 (Visual Studio 17 2022).
That's it. You're done. Refer to the User Guide section on how to use YCM.
Don't forget that if you want the C-family semantic completion engine to work,
you will need to provide the compilation flags for your project to YCM. It's all
in the User Guide.
YCM 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
The [full installation guide][wiki-full-install] has been moved to the wiki.
Quick Feature Summary
General (all languages)
Super-fast identifier completer including tags files and syntax elements
Intelligent suggestion ranking and filtering
File and path suggestions
Suggestions from Vim's omnifunc
UltiSnips snippet suggestions
C-family languages (C, C++, Objective C, Objective C++, CUDA)
Semantic auto-completion with automatic fixes
Signature help
Real-time diagnostic display
Go to include/declaration/definition (GoTo, etc.)
Go to alternate file (e.g. associated header GoToAlternateFile)
Find Symbol (GoToSymbol), with interactive search
Document outline (GoToDocumentOutline), with interactive search
View documentation comments for identifiers (GetDoc)
Type information for identifiers (GetType)
Automatically fix certain errors (FixIt)
Perform refactoring (FixIt)
Reference finding (GoToReferences)
Renaming symbols (RefactorRename <new name>)
Code formatting (Format)
Semantic highlighting
Inlay hints
Type hierarchy
Call hierarchy
C♯
Semantic auto-completion
Signature help
Real-time diagnostic display
Go to declaration/definition (GoTo, etc.)
Go to implementation (GoToImplementation)
Find Symbol (GoToSymbol), with interactive search
View documentation comments for identifiers (GetDoc)
Type information for identifiers (GetType)
Automatically fix certain errors (FixIt)
Perform refactoring (FixIt)
Management of OmniSharp-Roslyn server instance
Renaming symbols (RefactorRename <new name>)
Code formatting (Format)
Python
Semantic auto-completion
Signature help
Go to definition (GoTo)
Find Symbol (GoToSymbol), with interactive search
Reference finding (GoToReferences)
View documentation comments for identifiers (GetDoc)
Type information for identifiers (GetType)
Renaming symbols (RefactorRename <new name>)
Go
Semantic auto-completion
Signature help
Real-time diagnostic display
Go to declaration/definition (GoTo, etc.)
Go to type definition (GoToType)
Go to implementation (GoToImplementation)
Document outline (GoToDocumentOutline), with interactive search
Automatically fix certain errors (FixIt)
Perform refactoring (FixIt)
View documentation comments for identifiers (GetDoc)
Type information for identifiers (GetType)
Code formatting (Format)
Management of gopls server instance
Inlay hints
Call hierarchy
JavaScript and TypeScript
Semantic auto-completion with automatic import insertion
Signature help
Real-time diagnostic display
Go to definition (GoTo, GoToDefinition, and GoToDeclaration are
identical)
Go to type definition (GoToType)
Go to implementation (GoToImplementation)
Find Symbol (GoToSymbol), with interactive search
Reference finding (GoToReferences)
View documentation comments for identifiers (GetDoc)
Type information for identifiers (GetType)
Automatically fix certain errors and perform refactoring (FixIt)
Perform refactoring (FixIt)
Renaming symbols (RefactorRename <new name>)
Code formatting (Format)
Organize imports (OrganizeImports)
Management of TSServer server instance
Inlay hints
Call hierarchy
Rust
Semantic auto-completion
Real-time diagnostic display
Go to declaration/definition (GoTo, etc.)
Go to implementation (GoToImplementation)
Reference finding (GoToReferences)
Document outline (GoToDocumentOutline), with interactive search
View documentation comments for identifiers (GetDoc)
Automatically fix certain errors (FixIt)
Perform refactoring (FixIt)
Type information for identifiers (GetType)
Renaming symbols (RefactorRename <new name>)
Code formatting (Format)
Management of rust-analyzer server instance
Semantic highlighting
Inlay hints
Call hierarchy
Java
Semantic auto-completion with automatic import insertion
Signature help
Real-time diagnostic display
Go to definition (GoTo, GoToDefinition, and GoToDeclaration are
identical)
Go to type definition (GoToType)
Go to implementation (GoToImplementation)
Find Symbol (GoToSymbol), with interactive search
Reference finding (GoToReferences)
Document outline (GoToDocumentOutline), with interactive search
View documentation comments for identifiers (GetDoc)
Type information for identifiers (GetType)
Automatically fix certain errors including code generation (FixIt)
Renaming symbols (RefactorRename <new name>)
Code formatting (Format)
Organize imports (OrganizeImports)
Detection of Java projects
Execute custom server command (ExecuteCommand <args>)
Management of jdt.ls server instance
Semantic highlighting
Inlay hints
Type hierarchy
Call hierarchy
User Guide
General Usage
If the offered completions are too broad, keep typing characters; YCM will
continue refining the offered completions based on your input.
Filtering is "smart-case" and "smart-[diacritic][]" sensitive; if you are
typing only lowercase letters, then it's case-insensitive. If your input
contains uppercase letters, then the uppercase letters in your query must
match uppercase letters in the completion strings (the lowercase letters still
match both). On top of that, a letter with no diacritic marks will match that
letter with or without marks:
Use the TAB key to accept a completion and continue pressing TAB to cycle
through the completions. Use Shift-TAB to cycle backward. Note that if you're
using console Vim (that is, not gvim or MacVim) then it's likely that the
Shift-TAB binding will not work because the console will not pass it to Vim.
You can remap the keys; see the Options section below.
Knowing a little bit about how YCM works internally will prevent confusion. YCM
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).
There are also several semantic engines in YCM. There are libclang-based and
clangd-based completers that provide semantic completion for C-family languages.
There's a Jedi-based completer for semantic completion for Python. There's also
an omnifunc-based completer that uses data from Vim's omnicomplete system to
provide semantic completions when no native completer exists for that language
in YCM.
There are also other completion engines, like the UltiSnips completer and the
filepath completer.
YCM automatically detects which completion engine would be the best in any
situation. On occasion, it queries several of them at once, merges the
outputs and presents the results to you.
Client-Server Architecture
YCM has a client-server architecture; the Vim part of YCM is only a thin client
that talks to the [ycmd HTTP+JSON server][ycmd] that has the vast majority of
YCM 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
that 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). Word-boundary characters are all capital characters, characters
preceded by an underscore, and the first letter character in the completion
string.
Signature Help
Valid signatures are displayed in a second popup menu and the current signature
is highlighted along with the current argument.
Signature help is triggered in insert mode automatically when
g:ycm_auto_trigger is enabled and is not supported when it is not enabled.
The signatures popup is hidden when there are no matching signatures or when you
leave insert mode. If you want to manually control when it is visible, you can
map something to <plug>YCMToggleSignatureHelp (see below).
For more details on this feature and a few demos, check out the
[PR that proposed it][signature-help-pr].
Dismiss signature help
The signature help popup sometimes gets in the way. You can toggle its
visibility with a mapping. YCM provides the "Plug" mapping
<Plug>(YCMToggleSignatureHelp) for this.
For example, to hide/show the signature help popup by pressing Ctrl+l in insert
mode: imap <silent> <C-l> <Plug>(YCMToggleSignatureHelp).
NOTE: No default mapping is provided because insert mappings are very
difficult to create without breaking or overriding some existing functionality.
Ctrl-l is not a suggestion, just an example.
Semantic highlighting
Semantic highlighting is the process where the buffer text is coloured according
to the underlying semantic type of the word, rather than classic syntax
highlighting based on regular expressions. This can be powerful additional data
that we can process very quickly.
This feature is only supported in Vim.
For example, here is a function with classic highlighting:
And here is the same function with semantic highlighting:
As you can see, the function calls, macros, etc. are correctly identified.
This can be enabled globally with let g:ycm_enable_semantic_highlighting=1 or
per buffer, by setting b:ycm_enable_semantic_highlighting.
Customising the highlight groups
YCM uses text properties (see :help text-prop-intro) for semantic
highlighting. In order to customise the coloring, you can define the text
properties that are used.
If you define a text property named YCM_HL_<token type>, then it will be used
in place of the defaults. The <token type> is defined as the Language Server
Protocol semantic token type, defined in the LSP Spec.
Some servers also use custom values. In this case, YCM prints a warning
including the token type name that you can customise.
For example, to render parameter tokens using the Normal highlight group,
you can do this:
NOTE: Highly experimental feature, requiring Vim 9.0.214 or later (not
supported in NeoVim).
When g:ycm_enable_inlay_hints (globally) or b:ycm_enable_inlay_hints (for a
specific buffer) is set to 1, then YCM will insert inlay hints as supported by
the language semantic engine.
An inlay hint is text that is rendered on the screen that is not part of the buffer and
is often used to mark up the type or name of arguments, parameters, etc. which
help the developer understand the semantics of the code.
Here are some examples:
C
TypeScript
Go
Highlight groups
By default, YCM renders the inlay hints with the NonText highlight group. To
override this, define the YcmInlayHint highlight yourself, e.g. in your
.vimrc:
hi link YcmInlayHint Comment
Similar to semantic highlighting above, you can override specific highlighting
for different inlay hint types by defining text properties named after the kind
of inlay hint, for example:
The list of inlay hint kinds can be found in python/ycm/inlay_hints.py
Options
g:ycm_enable_inlay_hints or b:ycm_enable_inlay_hints - enable/disable
globally or for local buffer
g:ycm_clear_inlay_hints_in_insert_mode - set to 1 to remove all inlay
hints when entering insert mode and reinstate them when leaving insert mode
Toggling
Inlay hints can add a lot of text to the screen and may be distracting. You can
toggle them on/off instantly, by mapping something to
<Plug>(YCMToggleInlayHints), for example:
No default mapping is provided for this due to the personal nature of mappings.
General Semantic Completion
You can use Ctrl+Space to trigger the completion suggestions anywhere, even
without a string prefix. This is useful to see which top-level functions are
available for use.
C-family Semantic Completion
NOTE: YCM originally used the libclang based engine for C-family, but
users should migrate to clangd, as it provides more features and better
performance. Users who rely on override_filename in their .ycm_extra_conf.py
will need to stay on the old libclang engine. Instructions on how to stay on
the old engine are available on [the wiki][libclang-instructions].
Some of the features of clangd:
Project wide indexing: Clangd has both dynamic and static index support.
The dynamic index stores up-to-date symbols coming from any files you are
currently editing, whereas static index contains project-wide symbol
information. This symbol information is used for code completion and code
navigation. Whereas libclang is limited to the current translation unit(TU).
Code navigation: Clangd provides all the GoTo requests libclang provides and it
improves those using the above-mentioned index information to contain
project-wide information rather than just the current TU.
Rename: Clangd can perform semantic rename operations on the current
file, whereas libclang doesn't support such functionality.
Code Completion: Clangd can perform code completions at a lower latency
than libclang; also, it has information about all the symbols in your
project so it can suggest items outside your current TU and also provides
proper #include insertions for those items.
Signature help: Clangd provides signature help so that you can see the
names and types of arguments when calling functions.
Format Code: Clangd provides code formatting either for the selected
lines or the whole file, whereas libclang doesn't have such functionality.
Performance: Clangd has faster re-parse and code completion times
compared to libclang.
Installation
On supported architectures, the install.py script will download a suitable
clangd (--clangd-completer) or libclang (--clang-completer) for you.
Supported architectures are:
Linux glibc >= 2.39 (Intel, armv7-a, aarch64) - built on ubuntu 24.04
MacOS >=10.15 (Intel, arm64)
For Intel, compatibility per clang.llvm.org downloads
For arm64, macOS 10.15+
Windows (Intel) - compatibility per clang.llvm.org downloads
clangd:
Typically, clangd is installed by the YCM installer (either with --all or with
--clangd-completer). This downloads a pre-built clangd binary for your
architecture. If your OS or architecture is not supported or is too old, you can
install a compatible clangd and use g:ycm_clangd_binary_path to point to
it.
libclang:
libclang can be enabled also with --all or --clang-completer. As with
clangd, YCM will try and download a version of libclang that is suitable for
your environment, but again if your environment can't be supported, you can
build or acquire libclang for yourself and specify it when building, as:
Please note that if using custom clangd or libclang it must match the
version that YCM requires. Currently YCM requires clang 17.0.1.
Compile flags
In order to perform semantic analysis such as code completion, GoTo, and
diagnostics, YouCompleteMe uses clangd, which makes use of
clang compiler, sometimes also referred to as LLVM. Like any compiler,
clang also requires a set of compile flags in order to parse your code. Simply
put: If clang can't parse your code, YouCompleteMe can't provide semantic
analysis.
There are 2 methods that can be used to provide compile flags to clang:
Option 1: Use a [compilation database][compdb]
The easiest way to get YCM to compile your code is to use a compilation
database. A compilation database is usually generated by your build system
(e.g. CMake) and contains the compiler invocation for each compilation unit in
your project.
For information on how to generate a compilation database, see the [clang
documentation][compdb]. In short:
If using CMake, add -DCMAKE_EXPORT_COMPILE_COMMANDS=ON when configuring (or
add set( CMAKE_EXPORT_COMPILE_COMMANDS ON ) to CMakeLists.txt) and copy or
symlink the generated database to the root of your project.
If using Ninja, check out the compdb tool (-t compdb) in its
[docs][ninja-compdb].
If using GNU make, check out [compiledb][] or [Bear][].
If no .ycm_extra_conf.py is found,
YouCompleteMe automatically tries to load a compilation database if there is
one.
YCM looks for a file named compile_commands.json in the directory of the
opened file or in any directory above it in the hierarchy (recursively); when
the file is found before a local .ycm_extra_conf.py, YouCompleteMe stops
searching the directories and lets clangd take over and handle the flags.
Option 2: Provide the flags manually
If you don't have a compilation database or aren't able to generate one,
you have to tell YouCompleteMe how to compile your code some other way.
Every C-family project is different. It is not possible for YCM to guess what
compiler flags to supply for your project. Fortunately, YCM provides a mechanism
for you to generate the flags for a particular file with arbitrary complexity.
This is achieved by requiring you to provide a Python module that implements a
trivial function that, given the file name as an argument, returns a list of
compiler flags to use to compile that file.
YCM looks for a .ycm_extra_conf.py file in the directory of the opened file or
in any directory above it in the hierarchy (recursively); when the file is
found, it is loaded (only once!) as a Python module. YCM calls a Settings
method in that module which should provide it with the information necessary to
compile the current file. You can also provide a path to a global configuration
file with the
g:ycm_global_ycm_extra_conf option,
which will be used as a fallback. To prevent the execution of malicious code
from a file you didn't write YCM will ask you once per .ycm_extra_conf.py if
it is safe to load. This can be disabled and you can white-/blacklist files. See
the g:ycm_confirm_extra_conf and
g:ycm_extra_conf_globlist options
respectively.
This system was designed this way so that the user can perform any arbitrary
sequence of operations to produce a list of compilation flags YCM should hand
to Clang.
NOTE: It is highly recommended to include -x <language> flag to libclang.
This is so that the correct language is detected, particularly for header files.
Common values are -x c for C, -x c++ for C++, -x objc for Objective-C, and
-x cuda for CUDA.
To give you an impression, if your C++ project is trivial, and your usual
compilation command is: g++ -Wall -Wextra -Werror -o FILE.o FILE.cc, then the
following .ycm_extra_conf.py is enough to get semantic analysis from
YouCompleteMe:
As you can see from the trivial example, YCM calls the Settings method which
returns a dictionary with a single element 'flags'. This element is a list
of compiler flags to pass to libclang for the current file. The absolute path of
that file is accessible under the filename key of the kwargs dictionary.
That's it! This is actually enough for most projects, but for complex projects
it is not uncommon to integrate directly with an existing build system using the
full power of the Python language.
For a more elaborate example,
[see ycmd's own .ycm_extra_conf.py][ycmd_flags_example]. You should be able to
use it as a starting point. Don't just copy/paste that file somewhere and
expect things to magically work; your project needs different flags. Hint:
just replace the strings in the flags variable with compilation flags
necessary for your project. That should be enough for 99% of projects.
You could also consider using [YCM-Generator][ygen] to generate the
ycm_extra_conf.py file.
Errors during compilation
If Clang encounters errors when compiling the header files that your file
includes, then it's probably going to take a long time to get completions. When
the completion menu finally appears, it's going to have a large number of
unrelated completion strings (type/function names that are not actually
members). This is because Clang fails to build a precompiled preamble for your
file if there are any errors in the included headers and that preamble is key to
getting fast completions.
Call the :YcmDiags command to see if any errors or warnings were detected in
your file.
Java Semantic Completion
Java Quick Start
Ensure that you have enabled the Java completer. See the
installation guide for details.
Create a project file (gradle or maven) file in the root directory of your
Java project, by following the instructions below.
(Optional) Configure the LSP server. The [jdt.ls
configuration options][jdtls-preferences] can be found in their codebase.
If you previously used Eclim or Syntastic for Java, disable them for Java.
Edit a Java file from your project.
Java Project Files
In order to provide semantic analysis, the Java completion engine requires
knowledge of your project structure. In particular, it needs to know the class
path to use, when compiling your code. Fortunately [jdt.ls][]
supports [eclipse project files][eclipse-project],
[maven projects][mvn-project] and [gradle projects][gradle-project].
NOTE: Our recommendation is to use either Maven or Gradle projects.
Diagnostic display - Syntastic
The native support for Java includes YCM's native real-time diagnostics display.
This can conflict with other diagnostics plugins like Syntastic, so when
enabling Java support, please manually disable Syntastic Java diagnostics.
Add the following to your vimrc:
let g:syntastic_java_checkers = []
Diagnostic display - Eclim
The native support for Java includes YCM's native real-time diagnostics display.
This can conflict with other diagnostics plugins like Eclim, so when enabling
Java support, please manually disable Eclim Java diagnostics.
Add the following to your vimrc:
let g:EclimFileTypeValidate = 0
NOTE: We recommend disabling Eclim entirely when editing Java with YCM's
native Java support. This can be done temporarily with :EclimDisable.
Eclipse Projects
Eclipse-style projects require two files: [.project][eclipse-dot-project] and
[.classpath][eclipse-dot-classpath].
If your project already has these files due to previously being set up within
Eclipse, then no setup is required. [jdt.ls][] should load the project just
fine (it's basically eclipse after all).
However, if not, it is possible (easy in fact) to craft them manually, though it
is not recommended. You're better off using Gradle or Maven (see below).
[A simple eclipse style project example][ycmd-eclipse-project] can be found in
the ycmd test directory. Normally all that is required is to copy these files to
the root of your project and to edit the .classpath to add additional
libraries, such as:
NOTE: The eclipse project and classpath files are not a public interface
and it is highly recommended to use Maven or Gradle project definitions if you
don't already use Eclipse to manage your projects.
Maven Projects
Maven needs a file named [pom.xml][mvn-project] in the root of the project.
Once again a simple [pom.xml][ycmd-mvn-pom-xml] can be found in the ycmd source.
The format of [pom.xml][mvn-project] files is way beyond the scope of this
document, but we do recommend using the various tools that can generate them for
you, if you're not familiar with them already.
Gradle Projects
Gradle projects require a [build.gradle][gradle-project]. Again, there is a
[trivial example in ycmd's tests][ycmd-gradle-project].
The format of [build.gradle][gradle-project] files are way beyond the scope of
this document, but we do recommend using the various tools that can generate
them for you if you're not familiar with them already.
Some users have experienced issues with their jdt.ls when using the Groovy
language for their build.gradle. As such, try using
Kotlin instead.
Troubleshooting
If you're not getting completions or diagnostics, check the server health:
The Java completion engine takes a while to start up and parse your project.
You should be able to see its progress in the command line, and
:YcmDebugInfo. Ensure that the following lines are present:
-- jdt.ls Java Language Server running
-- jdt.ls Java Language Server Startup Status: Ready
If the above lines don't appear after a few minutes, check the jdt.ls and ycmd
log files using :YcmToggleLogs. The jdt.ls
log file is called .log (for some reason).
If you get a message about "classpath is incomplete", then make sure you have
correctly configured the project files.
If you get messages about unresolved imports, then make sure you have
correctly configured the project files, in particular
check that the classpath is set correctly.
C# Semantic Completion
YCM relies on [OmniSharp-Roslyn][] to provide completion and code navigation.
OmniSharp-Roslyn needs a solution file for a C# project and there are two ways
of letting YCM know about your solution files.
Automatically discovered solution files
YCM will scan all parent directories of the file currently being edited and look
for a file with .sln extension.
Manually specified solution files
If YCM loads .ycm_extra_conf.py which contains CSharpSolutionFile function,
YCM will try to use that to determine the solution file. This is useful when one
wants to override the default behaviour and specify a solution file that is not
in any of the parent directories of the currently edited file. Example:
def CSharpSolutionFile( filepath ):
# `filepath` is the path of the file user is editing
return '/path/to/solution/file' # Can be relative to the `.ycm_extra_conf.py`
If the path returned by CSharpSolutionFile is not an actual file, YCM will
fall back to the other way of finding the file.
Use with .NET 6.0 and .NET SDKs
YCM ships with older version of OmniSharp-Roslyn based on Mono runtime.
It is possible to use it with .NET 6.0 and newer, but it requires manual setup.
Download NET 6.0 version of the OmniSharp server for your system from
releases
Set g:ycm_roslyn_binary_path to the unpacked executable OmniSharp
Create a solution file if one doesn't already exist, it is currently required
by YCM for internal bookkeeping
Run dotnet new sln at the root of your project
Run dotnet sln add <project1.csproj> <project2.csproj> ...
for all of your projects
Run :YcmRestartServer
Python Semantic Completion
YCM relies on the [Jedi][] engine to provide completion and code navigation. By
default, it will pick the version of Python running the [ycmd server][ycmd] and
use its sys.path. While this is fine for simple projects, this needs to be
configurable when working with virtual environments or in a project with
third-party packages. The next sections explain how to do that.
Working with virtual environments
A common practice when working on a Python project is to install its
dependencies in a virtual environment and develop the project inside that
environment. To support this, YCM needs to know the interpreter path of the
virtual environment. You can specify it by creating a .ycm_extra_conf.py file
at the root of your project with the following contents:
Here, /path/to/virtual/environment/python is the path to the Python used
by the virtual environment you are working in. Typically, the executable can be
found in the Scripts folder of the virtual environment directory on Windows
and in the bin folder on other platforms.
If you don't like having to create a .ycm_extra_conf.py file at the root of
your project and would prefer to specify the interpreter path with a Vim option,
read the Configuring through Vim options
section.
Working with third-party packages
Another common practice is to put the dependencies directly into the project and
add their paths to sys.path at runtime in order to import them. YCM needs to
be told about this path manipulation to support those dependencies. This can be
done by creating a .ycm_extra_conf.py file at the root of the project. This
file must define a Settings( **kwargs ) function returning a dictionary with
the list of paths to prepend to sys.path under the sys_path key. For
instance, the following .ycm_extra_conf.py adds the paths
/path/to/some/third_party/package and /path/to/another/third_party/package
at the start of sys.path:
If you need further control on how to add paths to sys.path, you should define
the PythonSysPath( **kwargs ) function in the .ycm_extra_conf.py file. Its
keyword arguments are sys_path which contains the default sys.path, and
interpreter_path which is the path to the Python interpreter. Here's a trivial
example that inserts the /path/to/third_party/package path at the second
position of sys.path:
A more advanced example can be found in [YCM's own
.ycm_extra_conf.py][ycm_flags_example].
Configuring through Vim options
You may find it inconvenient to have to create a .ycm_extra_conf.py file at the
root of each one of your projects in order to set the path to the Python
interpreter and/or add paths to sys.path and would prefer to be able to
configure those through Vim options. Don't worry, this is possible by using the
g:ycm_extra_conf_vim_data option and
creating a global extra configuration file. Let's take an example. Suppose that
you want to set the interpreter path with the g:ycm_python_interpreter_path
option and prepend paths to sys.path with the g:ycm_python_sys_path option.
Suppose also that you want to name the global extra configuration file
global_extra_conf.py and that you want to put it in your HOME folder. You
should then add the following lines to your vimrc:
let g:ycm_python_interpreter_path = ''
let g:ycm_python_sys_path = []
let g:ycm_extra_conf_vim_data = [
\ 'g:ycm_python_interpreter_path',
\ 'g:ycm_python_sys_path'
\]
let g:ycm_global_ycm_extra_conf = '~/global_extra_conf.py'
Then, create the ~/global_extra_conf.py file with the following contents:
That's it. You are done. Note that you don't need to restart the server when
setting one of the options. YCM will automatically pick the new values.
Rust Semantic Completion
YCM uses [rust-analyzer][] for Rust semantic completion.
NOTE: Previously, YCM used [rls][] for rust completion. This is no longer
supported, as the Rust community has decided on [rust-analyzer][] as the future
of Rust tooling.
Completions and GoTo commands within the current crate and its dependencies
should work out of the box with no additional configuration (provided that you
built YCM with the --rust-completer flag; see the Installation
section for details). The install script takes care of
installing [the Rust source code][rust-src], so no configuration is necessary.
Completions and GoTo commands should work out of the box (provided that you
built YCM with the --go-completer flag; see the Installation
section for details). The server only works for projects with
the "canonical" layout.
NOTE: YCM originally used the [Tern][] engine for JavaScript but due to
[Tern][] not being maintained anymore by its main author and the [TSServer][]
engine offering more features, YCM is moving to [TSServer][]. This won't affect
you if you were already using [Tern][] but you are encouraged to do the switch
by deleting the third_party/ycmd/third_party/tern_runtime/node_modules
directory in YCM folder. If you are a new user but still want to use [Tern][],
you should pass the --js-completer option to the install.py script during
installation. Further instructions on how to set up YCM with [Tern][] are
available on [the wiki][tern-instructions].
All JavaScript and TypeScript features are provided by the [TSServer][] engine,
which is included in the TypeScript SDK. To enable these features, install
[Node.js 18+ and npm][npm-install] and call the install.py script with the
--ts-completer flag.
[TSServer][] relies on [the jsconfig.json file][jsconfig.json] for JavaScript
and [the tsconfig.json file][tsconfig.json] for TypeScript to analyze your
project. Ensure the file exists at the root of your project.
To get diagnostics in JavaScript, set the checkJs option to true in your
jsconfig.json file:
{
"compilerOptions": {
"checkJs": true
}
}
Semantic Completion for Other Languages
C-family, C#, Go, Java, Python, Rust, and JavaScript/TypeScript languages are
supported natively by YouCompleteMe using the [Clang][], [OmniSharp-Roslyn][],
[Gopls][], [jdt.ls][], [Jedi][], [rust-analyzer][], and [TSServer][] engines,
respectively. Check the installation section for instructions
to enable these features if desired.
Plugging an arbitrary LSP server
Similar to other LSP clients, YCM can use an arbitrary LSP server with the help
of g:ycm_language_server option. An
example of a value of this option would be:
Each dictionary contains the following keys: name, cmdline, port,
filetypes, capabilities, project_root_files, additional_workspace_dirs,
triggerCharacters, and settings. The full description of each key can be
found in the [ycmd][language_server-configuration] repository.
See the LSP Examples project for more
examples of configuring the likes of PHP, Ruby, Kotlin, and D.
LSP Configuration
Many LSP servers allow some level of user configuration. YCM enables this with
the help of .ycm_extra_conf.py files. Here's an example of jdt.ls user
examples of configuring the likes of PHP, Ruby, Kotlin, D, and many, many more.
The ls key tells YCM that the dictionary should be passed to the LSP server.
For each of the LSP server's configuration, you should look up the respective
server's documentation.
Some servers request settings from arbitrary 'sections' of configuration. There
is no concept of configuration sections in Vim, so you can specify an additional
config_sections dictionary which maps section to a dictionary of config
required by the server. For example:
The sections and options/values are completely server-specific and rarely well
documented.
Using omnifunc for semantic completion
YCM will use your omnifunc (see :h omnifunc in Vim) as a source for semantic
completions if it does not have a native semantic completion engine for your
file's filetype. Vim comes with rudimentary omnifuncs for various languages like
Ruby, PHP, etc. It depends on the language.
You can get a stellar omnifunc for Ruby with [Eclim][]. Just make sure you have
the latest Eclim installed and configured (this means Eclim >= 2.2.* and
Eclipse >= 4.2.*).
After installing Eclim remember to create a new Eclipse project within your
application by typing :ProjectCreate <path-to-your-project> -n ruby inside Vim
and don't forget to have let g:EclimCompletionMethod = 'omnifunc' in your
vimrc. This will make YCM and Eclim play nice; YCM will use Eclim's omnifuncs as
the data source for semantic completions and provide the auto-triggering and
subsequence-based matching (and other YCM features) on top of it.
Writing New Semantic Completers
You have two options here: writing an omnifunc for Vim's omnicomplete system
that YCM will then use through its omni-completer, or a custom completer for YCM
using the [Completer API][completer-api].
Here are the differences between the two approaches:
You have to use VimScript to write the omnifunc, but get to use Python to
write for the Completer API; this by itself should make you want to use the
API.
The Completer API is a much more powerful way to integrate with YCM and it
provides a wider set of features. For instance, you can make your Completer
query your semantic back-end in an asynchronous fashion, thus not blocking
Vim's GUI thread while your completion system is processing stuff. This is
impossible with VimScript. All of YCM's completers use the Completer API.
Performance with the Completer API is better since Python executes faster than
VimScript.
If you want to use the omnifunc system, see the relevant Vim docs with :h complete-functions. For the Completer API, see [the API docs][completer-api].
If you want to upstream your completer into YCM's source, you should use the
Completer API.
Diagnostic Display
YCM will display diagnostic notifications for the C-family, C#, Go, Java,
JavaScript, Rust, and TypeScript languages. Since YCM 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:
Icons show up in the Vim gutter on lines that have a diagnostic.
Regions of text related to diagnostics are highlighted (by default, a red
wavy underline in gvim and a red background in vim).
Moving the cursor to a line with a diagnostic echoes the diagnostic text.
Vim's location list is automatically populated with diagnostic data (off by
default, see options).
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 YCM check for any pending diagnostics updates.
You can force a full, blocking compilation cycle with the
:YcmForceCompileAndDiagnostics command (you may want to map that command to a
key; try putting nnoremap <F5> :YcmForceCompileAndDiagnostics<CR> in your
vimrc). Calling this command will force YCM 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.
YCM 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) YCM 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:ycm_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 YCM uses. For the signs
in the Vim gutter, the relevant groups are:
YcmErrorSign, which falls back to group SyntasticErrorSign and then
error if they exist
YcmWarningSign, which falls back to group SyntasticWarningSign and then
todo if they exist
You can also style the line that has the warning/error with these groups:
YcmErrorLine, which falls back to group SyntasticErrorLine if it exists
YcmWarningLine, which falls back to group SyntasticWarningLine if it
exists
Finally, you can also style the popup for the detailed diagnostics (it is shown
if g:ycm_show_detailed_diag_in_popup is set) using the group YcmErrorPopup,
which falls back to ErrorMsg.
Note that the line highlighting groups only work when the
g:ycm_enable_diagnostic_signs
option is set. If you want highlighted lines but no signs in the Vim gutter,
set the signcolumn option to no in your vimrc:
set signcolumn=no
The syntax groups used to highlight regions of text with errors/warnings:
YcmErrorSection, which falls back to group SyntasticError if it exists and
then SpellBad
YcmWarningSection, which falls back to group SyntasticWarning if it exists
and then SpellCap
Here's how you'd change the style for a group:
highlight YcmErrorLine guibg=#3f0000
Symbol Search
This feature requires Vim and is not supported in Neovim
YCM provides a way to search for and jump to a symbol in the current project or
document when using supported languages.
You can search for symbols in the current workspace when the GoToSymbol
request is supported and the current document when GoToDocumentOutline is
supported.
Here's a quick demo:
As you can see, you can type and YCM filters down the list as you type. The
current set of matches are displayed in a popup window in the centre of the
screen and you can select an entry with the keyboard, to jump to that position.
Any matches are then added to the quickfix list.
To enable:
nmap <something> <Plug>(YCMFindSymbolInWorkspace)
nmap <something> <Plug>(YCMFindSymbolInDocument)
e.g.
nmap <leader>yfw <Plug>(YCMFindSymbolInWorkspace)
nmap <leader>yfd <Plug>(YCMFindSymbolInDocument)
When searching, YCM opens a prompt buffer at the top of the screen for the
input and puts you in insert mode. This means that you can hit <Esc> to go
into normal mode and use any other input commands that are supported in prompt
buffers. As you type characters, the search is updated.
Initially, results are queried from all open filetypes. You can hit <C-f> to
switch to just the current filetype while the popup is open.
While the popup is open, the following keys are intercepted:
<C-j>, <Down>, <C-n>, <Tab> - select the next item
<C-k>, <Up>, <C-p>, <S-Tab> - select the previous item
<PageUp>, <kPageUp> - jump up one screenful of items
<PageDown>, <kPageDown> - jump down one screenful of items
<Home>, <kHome> - jump to first item
<End>, <kEnd> - jump to last item
<CR> - jump to the selected item
<C-c> cancel/dismiss the popup
<C-f> - toggle results from all file types or just the current filetype
The search is also cancelled if you leave the prompt buffer window at any time,
so you can use window commands <C-w>... for example.
Closing the popup
NOTE: Pressing <Esc> does not close the popup - you must use Ctrl-c
for that, or use a window command (e.g. <Ctrl-w>j) or the mouse to leave the
prompt buffer window.
Type/Call Hierarchy
This feature requires Vim and is not supported in Neovim
NOTE: This feature is highly experimental and offered in the hope that it is
useful. Please help us by reporting issues and offering feedback.
YCM provides a way to view and navigate hierarchies. The following hierarchies
are supported:
Type hierachy <Plug>(YCMTypeHierarchy): Display subtypes and supertypes
of the symbol under cursor. Expand down to subtypes and up to supertypes.
Call hierarchy <Plug>(YCMCallHierarchy): Display callees and callers of
the symbol under cursor. Expand down to callers and up to callees.
Take a look at this
for brief demo.
Hierarchy UI can be initiated by mapping something to the indicated plug
mappings, for example:
This opens a "modal" popup showing the current element in the hierarchy tree.
The current tree root is aligned to the left and child and parent nodes are
expanded to the right. Expand the tree "down" with <Tab> and "up" with <S-Tab>.
The "root" of the tree can be re-focused to the selected item with
<S-Tab> and further <S-Tab> will show the parents of the selected item. This
can take a little getting used to, but it's particularly important with multiple
inheritance where a "child" of the current root may actually have other,
invisible, parent links. <S-Tab> on that row will show these by setting the
display root to the selected item.
When the hierarchy is displayed, the following keys are intercepted:
<Tab>: Drill into the hierarchy at the selected item: expand and show
children of the selected item.
<S-Tab>: Show parents of the selected item. When applied to sub-types, this
will re-root the tree at that type, so that all parent types (are displayed).
Similar for callers.
<CR>: Jump to the symbol currently selected.
<Down>, <C-n>, <C-j>, j: Select the next item
<Up>, <C-p>, <C-k>, k; Select the previous item
Any other key: closes the popup without jumping to any location
Note: you might think the call hierarchy tree is inverted, but we think
this way round is more intuitive because this is the typical way that call
stacks are displayed (with the current function at the top, and its callers
below).
Commands
The :YcmRestartServer command
If the [ycmd completion server][ycmd] suddenly stops for some reason, you can
restart it with this command.
The :YcmForceCompileAndDiagnostics command
Calling this command will force YCM 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> :YcmForceCompileAndDiagnostics<CR> in your vimrc.
The :YcmDiags 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 :YcmCompleter FixIt, then (FixIt available) is
appended to the error or warning text. See the FixIt completer subcommand for
more information.
NOTE: The absence 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 c-sharp completer provides many fix-its but does not add this
additional indication.
The g:ycm_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 :YcmShowDetailedDiagnostic command
This command shows the full diagnostic text when the user's cursor is on the
line with the diagnostic.
An options argument can be passed. If the argument is popup the diagnostic
text will be displayed in a popup at the cursor position.
If you prefer the detailed diagnostic to always be shown in a popup, then
let g:ycm_show_detailed_diag_in_popup=1.
The :YcmDebugInfo 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 :YcmToggleLogs command
This command presents the list of logfiles created by YCM, the [ycmd
server][ycmd], and the semantic engine server for the current filetype, if any.
One of these logfiles can be opened in the editor (or closed if already open) by
entering the corresponding number or by clicking on it with the mouse.
Additionally, this command can take the logfile names as arguments. Use the
<TAB> key (or any other key defined by the wildchar option) to complete the
arguments or to cycle through them (depending on the value of the wildmode
option). Each logfile given as an argument is directly opened (or closed if
already open) in the editor. Only for debugging purposes.
The :YcmCompleter command
This command gives access to a number of additional IDE-like
features in YCM, for things like semantic GoTo, type
information, FixIt, and refactoring.
This command accepts a range that can either be specified through a selection in
one of Vim's visual modes (see :h visual-use) or on the command line. For
instance, :2,5YcmCompleter will apply the command from line 2 to line 5. This
is useful for the Format subcommand.
