Macro parens

[paulo-ferraz-oliveira]

-define(REPORT_INTERVAL, (timer:seconds(5))).

doesn't get formatted.

Should you consider removing the parens as so:

-define(REPORT_INTERVAL, timer:seconds(5)).

?

[awalterschulze]

We do not remove parens, as this sometimes causes bugs.
I remember @michalmuskala found a good example once.

It seems it does get formatted though.
I tried

-define(REPORT_INTERVAL, ( timer:seconds(5))).

and it formatted to

-define(REPORT_INTERVAL, (timer:seconds(5))).

Is it okay if we close this issue or did I miss what you were trying to say?

[michalmuskala]

Yes, erlfmt does not touch parentheses precisely because interactions with macros can be tricky. In particular consider the following:

-define(COMPUTE(X, Y), (X) * (Y)).
-define(COMPUTE2(X, Y), X * Y).

?COMPUTE(1 + 2, 3 + 4).
% expands to 
(1 + 2) * (3 + 4) == 21.

?COMPUTE2(1 + 2, 3 + 4).
% expands to 
1 + 2 * 3 + 4 == 11.

The outer parentheses can also change the meaning:

-define(COND(X, Y), (X orelse Y)).
-define(COND2(X, Y), X orelse Y).

false andalso ?COND(false, true).
% expands to 
false andalso (false orelse true) == false.

false andalso ?COND2(false, true).
% expands to 
false andalso false orelse true == true.

We still handle whitespace, indentation, etc, but never add or remove ( or ) in expressions.

[paulo-ferraz-oliveira]

The outer parentheses can also change the meaning:

Right you are; nice one. Thanks.

[paulo-ferraz-oliveira]

I see @michalmuskala already mentioned it here. Since my use case was very simple (as you can see from the example I posted) I didn't think of other consequences. I guess rebar3_format will probably fix it too.