consider adding support for fixing (single) file(s) to dart fix

[pq]

Related to: #43886.

Currently:

[~/src/repos/dart/sdk/pkg/_fe_analyzer_shared] (master) $ dart fix lib/src/parser/identifier_context_impl.dart 

*** The `fix` command is provisional and subject to change or removal in future releases. ***

Directory doesn't exist: lib/src/parser/identifier_context_impl.dart

Usage: dart fix [arguments]
-h, --help    Print this usage information.

Run "dart help" to see global options.

I would expect this to work.

[pq]

(Failing support, the error message should be improved.)

[bkonyi]

@pq do we plan on doing this any time soon? This issue should probably have an owner so it doesn't get lost.

[pq]

It's not planned yet. I'll self-assign to keep it alive.

[elektronik2k5]

@pq any progress? I'm in the process of setting up git hooks for incremental codebase health improvement and am very surprised that dart fix only operates at the directory resolution.

[pq]

Thanks for the ping @elektronik2k5 , I've been working mostly elsewhere and haven't dug into this one unfortunately.

/fyi @devoncarew @bwilkerson: maybe this is something to consider when we slate some time for CLI feature work...

@jwren : curious if this has any application internally (or if directories are the expected scope)?

[jwren]

dart fix operates on directory structure because the directory structure is required to resolve Dart (i.e. up to the nearest .packages file). Given that the work has to be done to resolve the whole directory anyways, I suspect, there is no real time difference for running the algorithm over a single file versus the directory.

With regard git hooks, perhaps the generic rule would be something along the lines of: for each pubspec file, validate that there are no dart fix changes with that CWD.

No one has requested this internally.

[bwilkerson]

If it becomes interesting to support fixing single files I expect that it won't be difficult. There might be some changes on the CLI side to accept a single file, and there might be some changes on the server side to accept a file, but by the time we go to build an AnalysisContextCollection everything should work fine with one or more files and directories. It seems likely that all we need to do is remove some code that's verifying that we're passing along a directory.

[elektronik2k5]

Thanks a lot for looking into it, @pq, @jwren and @bwilkerson!
Given this limitation, a very crude but quick way to implement file based linting can be:

1. Collect directories from input files: lib/utils/foo.dart => lib/utils
2. Filter directories to get only uniques: [lib/utils, lib/utils, lib] => [lib/utils, lib]
3. Remove subdirectories from the list: [lib/utils, lib] => [lib]
4. Run current implementation of dart fix per unique directory
5. Filter output to only contain input files from step 1
6. ???
7. PROFIT!!!

With some quick tinkering I got steps 1, 2 and 4 this shell one liner:

dirname {staged_files} | uniq | xargs sh -c 'for directory; do dart fix --apply "$directory"; done' sh

{staged_files} is a placeholder for the result of a shell glob or a list of files.

Any chance of implementing something like this properly, as part of dart fix itself in the near future? Or should I try to add the missing steps myself as a workaround?

[leafpetersen]

I just ran into this as well. The error message is pretty confusing, especially if you don't use --apply when you first run it.