[erlang-questions] Building C code in dep with rebar3: c_src not found

Igor Clark <>
Thu Jan 24 12:42:59 CET 2019


Hi Bryan! Thanks for getting back to me.

Turns out this only happens with the latest version 1.10.1 of the port compiler - I tried older versions and everything works out as expected. Seems I'm not the only one <https://github.com/blt/port_compiler/issues/55> who's seen this either. I'm going to pin pc to 1.9.1 in my project A, as everything works as I thought it should with that version.

Just to tidy up, to answer your question, yes it's an umbrella app - the 'parent' app B is one that I made with "rebar3 new release", and then added project A as a remote source dependency, i.e. from a git repo, into 'deps' in project B's rebar.config. I'm running rebar3 commands from top level in project B.

Appreciate your time!

best,
i

> On 24 Jan 2019, at 05:18, Bryan Paxton <> wrote:
> 
>  Hi,
> 
>  Is this a directory with a set of apps in it or is this an umbrella? (i.e., you have a top level rebar.config). AFAIK there's only two ways you can have local dependencies like this... in an umbrella or using checkout dependencies. 
> Either way could you share the rebar config for project B? In some loose form that is. 
>  I just made an umbrella using rebar3 and could not replicate the issue. Note that in an umbrella I must be top level when running rebar3 compile, etc. 
> --
> 
> Bryan
> 
> On 1/23/19 6:58 PM, Igor Clark wrote:
>> Reading it back, I'm not sure if I made this very clear:
>> 
>> - project A is an OTP app containing C port code in c_src, and the above rebar.config with port compiler info
>> - project B is another OTP app referencing project A as a source dependency in project B's rebar config
>> - when I build project A in its own dir with 'rebar3 compile', it compiles the C code as expected
>> - when I build project B in its own dir with 'rebar3 compile', it recognises the port compiler dependency in project A's rebar.config, downloads and compiles it, but then fails to compile project A as a dep, saying "found no source files"
>> 
>> So I need some way for the port compiler, when running in the context of the parent app A, to know the proper path for 'c_src' inside the source dependency B. Can't see how it could be any problem with the port compiler, not least because jiffy uses it fine, so I must be missing something!
>> 
>> Incidentally I added CXXFLAGS to the port_env as well, but no difference, as expected. Clutching at straws somewhat there. ;-)
>> 
>> I also tried using a Makefile, which I guess is the intended rebar3 way, and that seems to work - but I'd love to know what's happening here.
>> 
>> Cheers,
>> Igor
>> 
>> 
>> 
>> On Wed, Jan 23, 2019 at 7:35 PM Igor Clark < <mailto:>> wrote:
>> Hi everyone,
>> 
>> I have an simple app which has a C port in it. I have a rebar.config from which it builds correctly when I run 'rebar3 compile' inside the app directory:
>> 
>> > { erl_opts, [debug_info] }.
>> > { deps, [] }.
>> > 
>> > { plugins, [
>> >       { pc, { git, "https://github.com/blt/port_compiler.git <https://github.com/blt/port_compiler.git>", { tag, "v1.10.1" } } }
>> > ] }.
>> > 
>> > { provider_hooks, [
>> >       { pre, [
>> >               { compile, { pc, compile }},
>> >               { clean, { pc, clean }}
>> >       ] }
>> > ] }.
>> > 
>> > { port_specs, [
>> >       { "priv/bin/my_port_binary", [
>> >               "c_src/my_c_file.1.c",
>> >               "c_src/subdir/my_c_file_2.c"
>> >       ] }
>> > ] }.
>> > 
>> > { port_env, [
>> >       { "CFLAGS", "$CFLAGS -Ic_src/ -g -Wall -Werror -O2" }
>> > ] }.
>> 
>> 
>> Compiling this works fine. The artifact is created in priv/bin, and running myapp:module_info() inside the shell shows the right details.
>> 
>> However, when I try to include this app as a dependency, I get this error:
>> 
>> > ===> Found no source files for:
>> > "c_src/my_c_file.1.c"
>> > ===> Found no source files for:
>> > "c_src/subdir/my_c_file_2.c"
>> 
>> 
>> I've included src, c_src and rebar.config in the 'files' entry in src/my_app.app.src.
>> 
>> I've also included a jiffy dep as a test to make sure C code gets built correctly, and that works fine, but I can't see what jiffy's config has that I don't.
>> 
>> Anyone know what I'm missing to make this work?
>> 
>> Thanks very much!
>> Igor
>> 
>> 
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