new feature print successfully compiled file names

[c-bik]

Pre-Check

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If there isn't already way to do this (please point me to how), then this is a feature request.

Environment

N/A

Current behaviour

Assuming default is incremental compile, currently apart from ===> Compiling myapp, rebar3 compile doesn't say which files it compiled.

Expected behaviour

Rather, good to have:

[myapp] $ ls src/
module1.erl module2.erl

[myapp] $ rebar3 compile # first time
===> Compiling myapp
===> compiled myapp/src/module1.erl
===> compiled myapp/src/module2.erl

[myapp] $ rebar3 compile # if nothing changes
===> Compiling myapp

[myapp] $ touch src/module2.erl
[myapp] $ rebar3 compile # only module2 has changed
===> Compiling myapp
===> Compiled myapp/src/module2.erl

This helps rebar3 users to manually load the new compiled modules among others who aren't using Auto Compile and Load plugin.

[ferd]

Right now you only get this information if you enable debug output with DEBUG=1; it was initially judged too noisy (especially on large apps) and was consciously removed from the regular output. I'm not sure we want to re-enable it.

For what it's worth, even without an auto-compile and load plugin, you can use r3:compile() from within rebar3 shell in order to compile and re-load modules directly.

[c-bik]

👍 @ferd for work around. I feel the same way about the default 'noise' (was hesitating because of that to raise this).

However, last time I tried rebar3 shell I had issues with clustering (something related to epmd needs to be manually started before first node etc), I haven't checked recently how that works with latest version of rebar3 now. If that epmd bit is no longer an issue then IMHO rebar3 shell is the way-to-go!

Alternatively, can DEBUG=X (numbers highter that 1) be a good idea for this (or other similar optional debug features)? -- without the heavy DEBUG=1 baggage, full compiler command and env dump (for ports e.g.) which is perhaps also unnecessary to just know which files got compiled!

I guess I'm trying to propose, in general, more DEBUG granularity.

[ferd]

The distribution layer for rebar3 now attempts to boot its own EPMD if it isn't there: https://github.com/erlang/rebar3/blob/416176290b20e1e68c5901f83cccef71ec2bc322/src/rebar_dist_utils.erl#L66-L70 So that should at least take care of the problem.

And yeah, lack of debug granularity is certainly a problem. I don't think that there's a quick easy fix (since we only support 3 levels). It would probably be faster to write a verbose switch than refactor all of the tool to add that granularity.

[c-bik]

@ferd is there a way to tell rebar3 shell to use werl.exe (instead of erl.exe) for/if windows? I have got nothing against erl.exe except the annoance of not having TAB (or working correctly) to autocomplete erlang (specially module exported function list) in some shells (GitBash for one).

I like the verbose switch idea 👍

rebar3 -v compile or rebar3 --verbose compile can even be rebar3 -vvv compile etc. Looks more intuitive than DEBUG=1,2,3 (and of course it can be any command and not just compile).

Is there a plan to work on this?

[tsloughter]

I would like to have output like mix does in recent versions. It prints how many modules were compiled.

[tsloughter]

Though I'd leave out the "generated ... app", but having the number of compiled modules could be nice and actually useful while still being minimal.

Mix output:

λ mix compile
==> connection
Compiling 1 file (.ex)
Generated connection app
==> decimal
Compiling 1 file (.ex)
Generated decimal app
==> db_connection
Compiling 23 files (.ex)
Generated db_connection app
==> postgrex
Compiling 62 files (.ex)
warning: Enum.partition/2 is deprecated. Use Enum.split_with/2 instead
  lib/postgrex/error_code.ex:14

Generated postgrex app

Since we wouldn't want the "Generated" line maybe we could even make the whole thing one line:

λ rebar3 compile
==> connection (compiling 1 module)

[filmor]

@c-bik You can run rebar3 (and any other escript) with werl by specifying the ESCRIPT_EMULATOR environment variable. In a Git bash that would be

 ESCRIPT_EMULATOR=werl ./rebar3 shell

In cmd.exe it's

 set ESCRIPT_EMULATOR=werl
 escript rebar3 shell

[paulo-ferraz-oliveira]

What'll be the goal of the implementation here?

1. add an option to rebar.config to allow listing compiled modules (verbose)?
2. output the number of compiled modules (as proposed by @tsloughter)?
3. both?

[tsloughter]

I'd like to see a count.