Update clang tidy Contributing guide #106672
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Also disclaims the mismatch between clang-query and clang-tidy as discussed here https://discourse.llvm.org/t/inconsistency-between-hasdescendant-in-clang-query-and-clang-libtooling-matchers/80799/
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@llvm/pr-subscribers-clang-tools-extra @llvm/pr-subscribers-clang-tidy Author: None (MichelleCDjunaidi) ChangesUpdate the documentation to direct new users to the Github instead of the discontinued Phabricator archive. Also details more ways and information regarding clang-query usage. Partially resolves/disclaims #106656 and #106663 as per discussion in https://discourse.llvm.org/t/inconsistency-between-hasdescendant-in-clang-query-and-clang-libtooling-matchers/80799/. Also updates the out-of-tree guide. For context, I recently went through the Contributing guide while writing #102299, and many of these updates were from my experience trying to follow the guide. e.g. I was trying to link the shared library of an out-of-tree check as SHARED in CMake and encountered duplicate symbols like _ZTIN5clang4tidy14ClangTidyCheckE. It wasn't until I saw 84f137a that I found out I had to use MODULE. I also encountered the clang-query difference which was a surprise as the documentation said the two matchers were "virtually identical". Also, the -header-filter thing tripped me out until I found #25590 and #91400. Usually, when people say restrict and filter, they mean filter out (since -header-filter instead includes/filters in said headers). Full diff: https://github.com/llvm/llvm-project/pull/106672.diff 1 Files Affected:
diff --git a/clang-tools-extra/docs/clang-tidy/Contributing.rst b/clang-tools-extra/docs/clang-tidy/Contributing.rst
index 92074bd4dae8ba..e92e86621c684d 100644
--- a/clang-tools-extra/docs/clang-tidy/Contributing.rst
+++ b/clang-tools-extra/docs/clang-tidy/Contributing.rst
@@ -130,11 +130,12 @@ So you have an idea of a useful check for :program:`clang-tidy`.
First, if you're not familiar with LLVM development, read through the `Getting
Started with LLVM`_ document for instructions on setting up your workflow and
the `LLVM Coding Standards`_ document to familiarize yourself with the coding
-style used in the project. For code reviews we mostly use `LLVM Phabricator`_.
+style used in the project. For code reviews we currently use `LLVM Github`_,
+though historically we used Phabricator.
.. _Getting Started with LLVM: https://llvm.org/docs/GettingStarted.html
.. _LLVM Coding Standards: https://llvm.org/docs/CodingStandards.html
-.. _LLVM Phabricator: https://llvm.org/docs/Phabricator.html
+.. _LLVM Github: https://github.com/llvm/llvm-project
Next, you need to decide which module the check belongs to. Modules
are located in subdirectories of `clang-tidy/
@@ -336,13 +337,24 @@ a starting point for your test cases. A rough outline of the process looks like
The quickest way to prototype your matcher is to use :program:`clang-query` to
interactively build up your matcher. For complicated matchers, build up a matching
expression incrementally and use :program:`clang-query`'s ``let`` command to save named
-matching expressions to simplify your matcher. Just like breaking up a huge function
-into smaller chunks with intention-revealing names can help you understand a complex
-algorithm, breaking up a matcher into smaller matchers with intention-revealing names
-can help you understand a complicated matcher. Once you have a working matcher, the
-C++ API will be virtually identical to your interactively constructed matcher. You can
-use local variables to preserve your intention-revealing names that you applied to
-nested matchers.
+matching expressions to simplify your matcher.
+
+.. code-block:: console
+ clang-query> let c1 cxxRecordDecl()
+ clang-query> match c1
+
+Alternatively, pressing tab after a previous matcher's open brace would also show which
+matchers can be chained with the previous matcher, though some matchers that work may not
+be listed.
+
+Just like breaking up a huge function into smaller chunks with intention-revealing names
+can help you understand a complex algorithm, breaking up a matcher into smaller matchers
+with intention-revealing names can help you understand a complicated matcher.
+
+Once you have a working clang-query matcher, the C++ API will be the same or similar to your
+interactively constructed matcher (there will be cases where they differ slightly).
+You can use local variables to preserve your intention-revealing names that you applied
+to nested matchers.
Creating private matchers
^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -646,10 +658,13 @@ directory. The path to this directory is available in a lit test with the varia
Out-of-tree check plugins
-------------------------
+
Developing an out-of-tree check as a plugin largely follows the steps
-outlined above. The plugin is a shared library whose code lives outside
+outlined above, including creating a new module and doing the hacks to
+register the module. The plugin is a shared library whose code lives outside
the clang-tidy build system. Build and link this shared library against
-LLVM as done for other kinds of Clang plugins.
+LLVM as done for other kinds of Clang plugins. If using CMake, use the keyword
+MODULE while invoking add_library or llvm_add_library.
The plugin can be loaded by passing `-load` to `clang-tidy` in addition to the
names of the checks to enable.
@@ -664,6 +679,17 @@ compiled against the version of clang-tidy that will be loading the plugin.
The plugins can use threads, TLS, or any other facilities available to in-tree
code which is accessible from the external headers.
+Note that testing checks out of tree might involve getting ``llvm-lit`` from an
+installed version of LLVM through the `Stand-alone Builds`_ section. Alternatively,
+get `lit`_ following the `test-suite guide`_ and get the `FileCheck`_ binary, and
+write a version of `check_clang_tidy.py`_ to suit your needs.
+
+.. _Stand-alone Builds: https://llvm.org/docs/GettingStarted.html
+.. _test-suite guide: https://llvm.org/docs/TestSuiteGuide.html
+.. _lit: https://llvm.org/docs/CommandGuide/lit.html
+.. _FileCheck: https://llvm.org/docs/CommandGuide/FileCheck.html
+.. _check_clang_tidy.py: https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/test/clang-tidy/check_clang_tidy.py
+
Running clang-tidy on LLVM
--------------------------
@@ -690,8 +716,8 @@ warnings and errors. The script provides multiple configuration flags.
that the file names are matched against.
``run-clang-tidy.py clang-tidy/.*Check\.cpp`` will only analyze clang-tidy
checks. It may also be necessary to restrict the header files that warnings
- are displayed from using the ``-header-filter`` flag. It has the same behavior
- as the corresponding :program:`clang-tidy` flag.
+ are displayed from using the ``-exclude-header-filter`` flag. It has the same
+ behavior as the corresponding :program:`clang-tidy` flag.
* To apply suggested fixes ``-fix`` can be passed as an argument. This gathers
all changes in a temporary directory and applies them. Passing ``-format``
@@ -758,4 +784,4 @@ There is only one argument that controls profile storage:
* If you run :program:`clang-tidy` from within ``/foo`` directory, and specify
``-store-check-profile=.``, then the profile will still be saved to
- ``/foo/<ISO8601-like timestamp>-example.cpp.json``
+ ``/foo/<ISO8601-like timestamp>-example.cpp.json``
\ No newline at end of file
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AaronBallman
requested review from
carlosgalvezp,
LegalizeAdulthood,
AaronBallman and
njames93
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Do you need someone to land the changes on your behalf? |
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Yeah, I don't have write permissions, so I need someone to land the changes on my behalf. Thank you so much! @AaronBallman |
Thank you! We always appreciate improved documentation! |
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@MichelleCDjunaidi Congratulations on having your first Pull Request (PR) merged into the LLVM Project! Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR. Please check whether problems have been caused by your change specifically, as the builds can include changes from many authors. It is not uncommon for your change to be included in a build that fails due to someone else's changes, or infrastructure issues. How to do this, and the rest of the post-merge process, is covered in detail here. If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again. If you don't get any reports, no action is required from you. Your changes are working as expected, well done! |
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From another pull #106675, why is this failing the build-bot? Any ideas? Do I have to create a new PR just to fix this? @AaronBallman |
Sorry for missing that before landing, I'll fix it up. |
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This should now be resolved in 9712255 |
Did you try this on Windows? Because in my experience all these TAB-complete actions depend on GNU readline which doesn't work on Windows. |
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@LegalizeAdulthood Thanks for bringing this up because it slipped my mind to test it on Windows! I honestly have only tested it on Linux, and I currently don't have access to my laptop for the week. If anyone reads this and tests it out, please tell the results. I'll open a new PR to add the Windows exception if it doesn't work. (Or if there's a better workflow that LLVM uses, do tell.) |
Correct, it doesn't work out of the box on Windows. |
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I see; thanks for notifying me! Does anyone know of the workaround on Windows, or should I try to find it after I have access to my laptop? |
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There is no workaround on Windows currently; the issue is that tab autocompletion is handled via and that's not available on Windows; we don't have any fallback code for it.There is https://sourceforge.net/projects/mingweditline/ (no idea how well it would work in practice), so perhaps there's a different library we could consume on Windows to provide the functionality. |
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Hmm, in that case, would it be better to note the Windows exception in the documentation and open up an issue tracker for the tab issue instead, since the bug and fix (due to it affecting all tab-related operations on Windows) is out of scope for this documentation PR? Also, what's the workflow for adding to a merger PR? Just make a new PR, correct? |
I think that approach makes sense!
Correct, making a new PR is the way to go. |
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Will open the issue soon (since mobile Github is accessible), but the additional new PR will be in a few days (no access to laptop currently) |
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PR opened on the linetab issue. |
Update the documentation to direct new users to the Github instead of the discontinued Phabricator archive. Also details more ways and information regarding clang-query usage. Partially resolves/disclaims #106656 and #106663 as per discussion in https://discourse.llvm.org/t/inconsistency-between-hasdescendant-in-clang-query-and-clang-libtooling-matchers/80799/.
Also updates the out-of-tree guide.
For context, I recently went through the Contributing guide while writing #102299, and many of these updates were from my experience trying to follow the guide. e.g. I was trying to link the shared library of an out-of-tree check as SHARED in CMake and encountered duplicate symbols like _ZTIN5clang4tidy14ClangTidyCheckE. It wasn't until I saw 84f137a that I found out I had to use MODULE. I also encountered the clang-query difference which was a surprise as the documentation said the two matchers were "virtually identical". Also, the -header-filter thing tripped me out until I found #25590 and #91400. Usually, when people say restrict and filter, they mean filter out (since -header-filter instead includes/filters in said headers).