pw_ide/docs.rst

.. _module-pw_ide:

------
pw_ide
------
This module provides tools for supporting code editor and IDE features for
Pigweed projects.

Usage
=====

Setup
-----
Most of the time, ``pw ide sync`` is all you need to get started.

.. _module-pw_ide-configuration:

Configuration
-------------
``pw_ide`` has a built-in default configuration. You can create a configuration
file if you need to override those defaults.

A project configuration can be defined in ``.pw_ide.yaml`` in the project root.
This configuration will be checked into source control and apply to all
developers of the project. Each user can also create a ``.pw_ide.user.yaml``
file that overrides both the default and project settings, is not checked into
source control, and applies only to that checkout of the project. All of these
files have the same schema, in which these options can be configured:

.. autoproperty:: pw_ide.settings.PigweedIdeSettings.working_dir
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.compdb_gen_cmd
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.compdb_search_paths
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.target_inference
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.targets_include
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.targets_exclude
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.default_target
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.cascade_targets
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.sync
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.clangd_additional_query_drivers
.. autoproperty:: pw_ide.settings.PigweedIdeSettings.editors

C++ Code Intelligence
---------------------
`clangd <https://clangd.llvm.org/>`_ is a language server that provides C/C++
code intelligence features to any editor that supports the language server
protocol (LSP). It uses a
`compilation database <https://clang.llvm.org/docs/JSONCompilationDatabase.html>`_,
a JSON file containing the compile commands for the project. Projects that have
multiple targets and/or use multiple toolchains need separate compilation
databases for each target toolchain. ``pw_ide`` provides tools for managing
those databases.

Assuming you have one or more compilation databases that have been generated by
your build system, start with:

.. code-block:: bash

   pw ide sync

This command will:

- Find every compilation database in your build directory

- Analyze each database

  - If a database is internally consistent (i.e., it only contains valid
    compile commands for a single target), it will use that database as-is for
    the target toolchain that database pertains to. This is the typical case for
    CMake builds.

  - Otherwise, if a database contains commands for multiple target toolchains
    and/or contains invalid compile commands, the database will be processed,
    yielding one new compilation database for each target toolchain. Those
    databases will be used instead of the original.

- Link each target to its respective compilation database

Now, you can list the available target toolchains with:

.. code-block:: bash

   pw ide cpp --list

Then set the target toolchain that ``clangd`` should use with:

.. code-block:: bash

   pw ide cpp --set <selected target name>

``clangd`` will now work as designed since it is configured to use a compilation
database that is consistent to just a single target toolchain.

``clangd`` must be run with arguments that provide the Pigweed environment paths
to the correct toolchains and sysroots. One way to do this is to launch your
editor from the terminal in an activated environment (e.g. running ``vim`` from
the terminal), in which case nothing special needs to be done as long as your
toolchains are in the Pigweed environment or ``$PATH``. But if you launch your
editor outside of the activated environment (e.g. launching Visual Studio Code
from your GUI shell's launcher), you can generate the command that invokes
``clangd`` with the right arguments with:

.. code-block:: bash

   pw ide cpp --clangd-command

Python Code Intelligence
------------------------
Any Python language server should work well with Pigweed projects as long as
it's configured to use the Pigweed virtual environment. You can output the path
to the virtual environment on your system with:

.. code-block:: bash

   pw ide python --venv

Docs Code Intelligence
----------------------
The `esbonio <https://github.com/swyddfa/esbonio>`_ language server will provide
code intelligence for RestructuredText and Sphinx. It works well with Pigweed
projects as long as it is pointed to Pigweed's Python virtual environment. For
Visual Studio Code, simply install the esbonio extension, which will be
recommended to you after setting up ``pw_ide``. Once it's installed, a prompt
will ask if you want to automatically install esbonio in your Pigweed Python
environment. After that, give esbonio some time to index, then you're done!

Command-Line Interface Reference
--------------------------------
.. argparse::
   :module: pw_ide.cli
   :func: _build_argument_parser
   :prog: pw ide

Design
======

Supporting ``clangd`` for Embedded Projects
-------------------------------------------
There are three main challenges that often prevent ``clangd`` from working
out-of-the-box with embedded projects:

#. Embedded projects cross-compile using alternative toolchains, rather than
   using the system toolchain. ``clangd`` doesn't know about those toolchains
   by default.

#. Embedded projects (particularly Pigweed project) often have *multiple*
   targets that use *multiple* toolchains. Most build systems that generate
   compilation databases put all compile commands in a single database, meaning
   a single file can have multiple, conflicting compile commands. ``clangd``
   will typically use the first one it finds, which may not be the one you want.

#. Pigweed projects have build steps that use languages other than C/C++. These
   steps are not relevant to ``clangd`` but many build systems will include them
   in the compilation database anyway.

To deal with these challenges, ``pw_ide`` processes the compilation database you
provide, yielding one or more compilation databases that are valid, consistent,
and specific to a particular target toolchain. This enables code intelligence
and navigation features that reflect that build.

After processing a compilation database, ``pw_ide`` knows what target toolchains
are available and provides tools for selecting which target toolchain is active.
These tools can be integrated into code editors, but are ultimately CLI-driven
and editor-agnostic. Enabling code intelligence in your editor may be as simple
as configuring its language server protocol client to use the ``clangd`` command
that ``pw_ide`` can generate for you.

When to provide additional configuration to support your use cases
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The default configuration for ``clangd`` in ``pw_ide`` should work without
additional configuration as long as you're using only toolchains provided by
Pigweed and your native host toolchain. If you're using other toolchains, keep
reading.

``clangd`` needs two pieces of information to use a toolchain:

#. A path to the compiler, which will be taken from the compile command.

#. The same compiler to be reflected in the
   `query driver <https://releases.llvm.org/10.0.0/tools/clang/tools/extra/docs/clangd/Configuration.html>`_
   argument provided when running ``clangd``.

When using ``pw_ide`` with external toolchains, you only need to add a path to
the compiler to ``clangd_additional_query_drivers`` in your project's
``pw_ide.yaml`` file. When processing a compilation database, ``pw_ide`` will
use the query driver globs to find your compiler and configure ``clangd`` to
use it.

Compiler wrappers
^^^^^^^^^^^^^^^^^
If you're using ``ccache`` or any other wrapper command that is configured
using ``ccache``'s' ``KEY=VALUE`` pattern, it will work out of the box.

Selected API Reference
^^^^^^^^^^^^^^^^^^^^^^
.. automodule:: pw_ide.cpp
   :members: CppCompileCommand, CppCompilationDatabase, CppCompilationDatabasesMap, CppIdeFeaturesState, path_to_executable, ClangdSettings

Automated Support for Code Editors & IDEs
-----------------------------------------
``pw_ide`` provides a consistent framework for automatically applying settings
for code editors, where default settings can be defined within ``pw_ide``,
which can be overridden by project settings, which in turn can be overridden
by individual user settings.

.. _module-pw_ide-vscode:

Visual Studio Code
^^^^^^^^^^^^^^^^^^
Running ``pw ide sync`` will automatically generate settings for Visual Studio
Code. ``pw_ide`` comes with sensible defaults for Pigweed projects, but those
can be augmented or overridden at the project level or the user level using
``pw_project_settings.json`` and ``pw_user_settings.json`` respectively. The
generated ``settings.json`` file is essentially a build artifact and shouldn't
be committed to source control.

.. note::

   You should treat ``settings.json`` as a build artifact and avoid editing it
   directly. However, if you do make changes to it, don't worry! The changes
   will be preserved after running ``pw ide sync``

The same pattern applies to ``tasks.json``, which provides Visual Studio Code
tasks for ``pw_ide`` commands. Access these by opening the command palette
(Ctrl/Cmd-Shift-P), selecting ``Tasks: Run Task``, then selecting the desired
task.

The same pattern also applies to ``launch.json``, which is used to define
configurations for running and debugging your project. Create a
``pw_project_launch.json`` with configurations that conform to the Visual Studio
Code `debugger configuration format <https://code.visualstudio.com/docs/editor/debugging>`_.

.. tip::

   What's the difference between "Change C++ Code Analysis Target" and "Set C++
   Code Analyis Target"? "Set" will automatically restart the ``clangd``
   language server for you to pick up the changed target immediately, while
   "Change" will not.

Selected API Reference
^^^^^^^^^^^^^^^^^^^^^^
.. automodule:: pw_ide.editors
   :members: EditorSettingsDefinition, EditorSettingsFile, EditorSettingsManager

.. automodule:: pw_ide.vscode
   :members: VscSettingsType, VscSettingsManager