Theia - Cpp Extension

This extension uses Clangd to
provide LSP features.

To install Clangd on Ubuntu 18.04:

$ wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
$ echo "deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic main" | sudo tee /etc/apt/sources.list.d/llvm.list
$ sudo apt-get update && sudo apt-get install -y clang-tools-8
$ sudo ln -s /usr/bin/clangd-8 /usr/bin/clangd

See here for detailed
installation instructions.

Getting accurate diagnostics

To get accurate diagnostics, it helps to:

1. Have the build system of the C/C++ project generate a
compile_commands.json
file.
2. Point Clangd to the build directory containing said compile_commands.json.

Step \#2 can be done using the cpp.buildConfigurations preference. In your
home or your project .theia/settings.json, define one or more build
configurations:

{
"cpp.buildConfigurations": [{
"name": "Release",
"directory": "/path/to/my/release/build"
},{
"name": "Debug",
"directory": "/path/to/my/debug/build"
}]
}

You can then select an active configuration using the C/C++: Change Build
Configuration command from the command palette.

Setting clangd executable path and arguments

The path of the clangd executable to use can be specified by either:

- Setting the CPP_CLANGD_COMMAND environment variable
- Setting the cpp.clangdExecutable preference in your home or your project
.theia/settings.json:

{
"cpp.clangdExecutable": "/path/to/my/clangd/executable"
}

- Adding clangd to system path. Default value of executable path is set to
clangd

Similarly, the command-line arguments passed to clangd can be specified by
either:

- Setting the CPP_CLANGD_ARGS environment variable
- Setting the cpp.clangdArgs preference in your home or your project
.theia/settings.json:

{
"cpp.clangdArgs": "list of clangd arguments"
}

Getting cross-file references to work

You may notice that by default, cross-references across source file boundaries
don't work. For example, doing a "Go To Definition" on a function defined in a
different source file (different .c or .cpp) doesn't work, instead it sends
you to the declaration of the function, typically in a header file.

To get this working, you need to enable clangd's global index using the
--background-index command-line argument.

{
"cpp.clangdArgs": "--background-index"
}

Using the clang-tidy linter

Note: This functionality is available when using clangd 9 and later.

You can set the preference 'cpp.clangTidy' to enable the clang-tidy linter included in clangd. When the preference is set, there are two ways to chose which of its built-in checks clang-tidy will use:

- using the preferences: 'cpp.clangTidyChecks'
- using the file '.clang-tidy' . The file is located in the same folder of the files or a parent folder.

Note: using the preference checks will supersede the value found in the .clang-tidy file.

The syntax used to fill the checks can be found at http://clang.llvm.org/extra/clang-tidy/

clang-tidy has its own checks and can also run Clang static analyzer checks. Each check has a name (see link above for full list). Clang-tidy takes as input the checks that should run, in the form of a comma-separated list of positive and negative (prefixed with -) globs. Positive globs add subsets of checks, negative globs remove them.

There are two ways to configure clang-tidy's checks: through a Theia preference or using a .clang-tidy config file. Here are examples for both:"

- for the preferences: "cpp.clangTidyChecks": ",-readability-"
- Meaning: enables all list-checks and disable all readability-* checks

- for the .clang-tidy file: Checks: "-,readability-"
- Meaning: disable all list-checks and enable all readability-* checks

License

- Eclipse Public License 2.0
- 一 (Secondary) GNU General Public License, version 2 with the GNU Classpath Exception