ERL-345: Cannot compile NIFs for modules with dots in name

[OTP-Maintainer]

Original reporter: ukasiu
Affected version: Not Specified
Component: Not Specified
Migrated from: https://bugs.erlang.org/browse/ERL-345

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I'm trying to compile NIF with {{STATIC_ERLANG_NIF}} to use in Elixir. {{ERL_NIF_INIT}} looks like this {{ERL_NIF_INIT(Elixir.FastCompare, nif_funcs, NULL, NULL, NULL, NULL)}} -- {{MODNAME}} contains dot. I'm getting this when trying to compile:

{noformat}
In file included from fast_compare.c:2:0:
fast_compare.c:20:20: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
 ERL_NIF_INIT(Elixir.FastCompare, nif_funcs, NULL, NULL, NULL, NULL)
                    ^
.../erts-8.2.1/include/erl_nif.h:264:51: note: in definition of macro 'ERL_NIF_INIT_DECL'
 #  define ERL_NIF_INIT_DECL(MODNAME) ErlNifEntry* MODNAME ## _nif_init(ERL_NIF_INIT_ARGS)
                                                   ^
fast_compare.c:20:1: note: in expansion of macro 'ERL_NIF_INIT'
 ERL_NIF_INIT(Elixir.FastCompare, nif_funcs, NULL, NULL, NULL, NULL)
 ^
fast_compare.c:20:20: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
 ERL_NIF_INIT(Elixir.FastCompare, nif_funcs, NULL, NULL, NULL, NULL)
                    ^
.../erts-8.2.1/include/erl_nif.h:264:51: note: in definition of macro 'ERL_NIF_INIT_DECL'
 #  define ERL_NIF_INIT_DECL(MODNAME) ErlNifEntry* MODNAME ## _nif_init(ERL_NIF_INIT_ARGS)
                                                   ^
fast_compare.c:20:1: note: in expansion of macro 'ERL_NIF_INIT'
 ERL_NIF_INIT(Elixir.FastCompare, nif_funcs, NULL, NULL, NULL, NULL)
 ^
{noformat}

[OTP-Maintainer]

sverker said:

It uses the module name to form a C identifier for the init function
and C identifiers cannot contain dots.

A dynamic NIF module with dot in the name should work I think.

[OTP-Maintainer]

ukasiu said:

Yep, but dynamic NIFs don't work on Android/arm7 -- I'm getting SEGFAULTs (which is probably another bug) on erlang:load_nif irrespectively to presence of `.so` file.

[OTP-Maintainer]

sverker said:

I think the easiest solution to this would be a new ERL_NIF_INIT_X macro
that separates module name and C identifier.

[OTP-Maintainer]

josevalim said:

This code works as expected and it defines Elixir.Markdown, with a dot: https://github.com/devinus/markdown/blob/master/src/markdown.c#L125

What am I missing?

[OTP-Maintainer]

ukasiu said:

You're missing {{#define STATIC_ERLANG_NIF}}

[sverker]

Fix #5477 merged to master for OTP 25.0.