I will provide some examples of why this is a serious problems:

First problem: The tests doesn't run properly

The tests aren't even tested, this can be proved by going into a test and change the indentation to be broken. Then run the test. If you do this in any indentation related test that I've added on master you will see that it passed. And if you apply the change from a30e883 and run the test again you will see that it failed (not only because of the changed file though, but that's the second problem).

But to prevent this in the future I've added a testcase with broken indentation that requires it to be indented and then have a check that looks that the buffer is not the same as the file instead of the reverse. This way we can know if it breaks the same way again.

Second problem: The tests indent badly

This can be demonstrated by first fixing the first issue, just by dropping a line and then removing running the tests and look at the following output:

Example:

let
  x = [
    (let y = 1; in y)
    { foo = 1; }
    [ 1 2 3 ]
    x
  ];
in x

becomes

let
  x = [
    (let y = 1; in y)
      { foo = 1; }
        [ 1 2 3 ]
          x
  ];
in x

and

[
  1
  false
  true
  https://nixos.org/
  {
    attr = "set";
  }
  [
    "nested"
    "list"
  ]
  "string"
]

becomes

[
  1
  false
  true
  https://nixos.org/
  {
    attr = "set";
  }
      [
        "nested"
      "list"
      ]
        "string"
]

And that was fixed in 1f922d7. I haven't reflected at all over if the regex is correct or not. I just grabbed the old one that was in use before the refactoring and cleanups. So it worked before with the one and seems to work now as well with 1f922d7.

So at the moment it's to me clearly broken.

cc @grahamc @matthewbauer

There are some problems with handling empty lists and sets:

{
}

is being indented as

{
  }

and

{
x = [
];
}

as

{
  x = [
    ];
}

As soon as there is at least 1 element, it seems to work fine.

Also this it the reason why it behaves weirdly with electric-pair-mode.

Another case:

{
  a = {
    x1="abc";
  };
b = {
  x2 = 1;
};
}

is just left as is on attempt to indent. But if you add spaces to x1 = "abc";, it'll indent correctly.

@wedens I have just tested these cases in some fixes before this PR is scoped for fixing. And the same issues seems to have existed back in 6445ebf as well.

So it would be nice if you could put them as a separate issue so we can track it separately and fix a bunch of issues at the time :)

@etu Ok. I've created a new issue #69.
I'm not sure about #63, but IIRC there were no issues with empty lists/sets in #61.

@matthewbauer can you merge? some melpa users are getting the one with regressions.

{
  a = [
    ];
}

was a problem before this PR.

Yeah sorry for the delay

Thank you! Do you know if we can get this update to 18.09 too, or are they doomed until19.03?

I think we can bump melpa for them! There were some issues with the recent update though that i'd want to make sure are resolved:

• emacsPackages.shrink-whitespace.src returns 404 nixpkgs#53280
• Building emacsPackages.notmuch fails with "Failed to connect to git.notmuchmail.org port 443: Connection refused" on master nixpkgs#53279