Fix for old clang-format

[JohanBertrand]

Related Issue(s)
Has Unit Tests (y/n)
Documentation Included (y/n)

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Change Description

Clang-format did not support a file path in its --style=file parameter before clang-format 14.0.

The current default clang format on ubuntu 20.04 is 10.0, and is not compatible with the current version of the tool, which is (I guess), responsible of some issues for users (see nasa/fprime#1101 (reply in thread))

This MR restores compatibility with older clang-format versions.

I also added distinction between verbose and quiet options for the formatter.

Rationale

Restore compatibility with older clang-format versions

[thomas-bc]

From clang-format docs:

When using -style=file, clang-format for each input file will try to find the .clang-format file located in the closest parent directory of the input file. When the standard input is used, the search is started from the current directory.

Since the fprime .clang-format lives in fprime/.clang-format, this will not be able to catch the format file if you are formatting a file outside of fprime/ (i.e. in your project, say in HelloWorldProject/Components/MyComponent/)

Ways I can think of to deal with this:

• have .clang-format be copied to the project's root when running fprime-bootstrap project. This would mean projects could tweak with how they like their formatting, which may be good. But I am not sure I like the idea of duplicating the file...
• if older version, warn and fallback to a default style
• well.. I'm out of ideas

Let me know what you think! Or if you can think of better alternatives

[LeStarch]

Am I missing something? I pulled up clang-format 10.0.0 documentation (https://releases.llvm.org/10.0.0/tools/clang/docs/ClangFormat.html) and it says that -style=file is supported.

  --style=<string>           - Coding style, currently supports:
                                 LLVM, Google, Chromium, Mozilla, WebKit.
                               Use -style=file to load style configuration from
                               .clang-format file located in one of the parent
                               directories of the source file (or current
                               directory for stdin).
                               Use -style="{key: value, ...}" to set specific
                               parameters, e.g.:
                                 -style="{BasedOnStyle: llvm, IndentWidth: 8}"

[thomas-bc]

@LeStarch the difference is between --style=file, which recurses up directories until it finds a .clang-format and --style=file:<path-to-clang-format> which uses the file at the given path.

We currently use the latter, pointing to <project>/fprime/.clang-format

[LeStarch]

@thomas-bc I see. The above means literally --style=file and the new is literally --style=file:/some/path now I see.

I am in-favor of cloning configuration out of fprime into projects (e.g. fprime/config -> project/config, fprime/.clang-format -> project/.clang-format, ect). Although this makes the upgrade path harder, it makes the customization story much easier.

If you @thomas-bc concur, we can merge this, and fix the project creation in a separate PR.

[JohanBertrand]

I am also liking the first option, since it will allow third parties to use their own .clang-format and fprime-util format if needed.

I would have liked to have an option on fprime-util to specify the .clang-format file to be used as an optional parameter. This could work easily with version of clang-tidy >= 14.0, but not for the older versions. The only way I found to do so, is to copy temporarily the .clang-format file in the folder of the formatted file, but I don't think it's worth it.

If you think it is something worth having, I can later work on adding a version check and allow the user to specify the style file only if the version of clang-tidy is >= 14.0.

[LeStarch]

What is the behavior in this case? If it fails, then the solution is obvious: add a .clang-format. If it formats with the default clang-format, good it has a defined format.

[thomas-bc]

I meant to say --fallback-style from clang-format: https://clang.llvm.org/docs/ClangFormat.html

[LeStarch]

Could we not just accept "LLVM" as a reasonable fallback style for projects that don't define a .clang-format? It is the default after all.

[thomas-bc]

I also do like your idea of having fprime-util format check the existence of a .clang-format file at the root of the project and if it doesn't exist -> automatically create one.
This gently pushes for best practice, and will ensure older projects get up to speed on this new file that should be at the root of the project.

[LeStarch]

I wasn't suggesting that, but it is a good idea!

[JohanBertrand]

I reverted a change in the subprocess.run() call, since my change did not have any impact on the execution of the function