current directory: /home/anatol/sources/vagrant/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.10/ext/ffi_c
/usr/bin/ruby -r ./siteconf20160108-18494-10jbhuj.rb extconf.rb
checking for ffi_call() in -lffi... yes
checking for ffi_prep_closure()... yes
checking for ffi_raw_call()... yes
checking for ffi_prep_raw_closure()... yes
checking for rb_thread_blocking_region()... no
checking for rb_thread_call_with_gvl()... yes
checking for rb_thread_call_without_gvl()... yes
checking for ffi_prep_cif_var()... yes
creating extconf.h
creating Makefile

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /home/anatol/sources/vagrant/vendor/bundle/ruby/2.3.0/extensions/x86_64-linux/2.3.0/ffi-1.9.10/mkmf.log

current directory: /home/anatol/sources/vagrant/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.10/ext/ffi_c
make "DESTDIR=" clean

current directory: /home/anatol/sources/vagrant/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.10/ext/ffi_c
make "DESTDIR="
compiling MethodHandle.c
compiling MemoryPointer.c
compiling LongDouble.c
compiling Types.c
compiling LastError.c
compiling Variadic.c
compiling StructByReference.c
compiling AbstractMemory.c
compiling FunctionInfo.c
compiling ArrayType.c
compiling ffi.c
compiling Pointer.c
compiling Function.c
Function.c: In function ‘async_cb_event’:
Function.c:563:9: warning: implicit declaration of function ‘rb_thread_call_without_gvl’ [-Wimplicit-function-declaration]
         rb_thread_call_without_gvl(async_cb_wait, &w, async_cb_stop, &w);
         ^
compiling DataConverter.c
compiling DynamicLibrary.c
compiling Buffer.c
compiling Thread.c
compiling Type.c
compiling StructByValue.c
compiling StructLayout.c
compiling MappedType.c
compiling Struct.c
compiling ClosurePool.c
compiling Platform.c
compiling Call.c
In file included from Call.c:62:0:
Call.c: In function ‘do_blocking_call’:
Thread.h:78:39: warning: implicit declaration of function ‘rb_thread_call_without_gvl’ [-Wimplicit-function-declaration]
 # define rbffi_thread_blocking_region rb_thread_call_without_gvl
                                       ^
Call.c:368:5: note: in expansion of macro ‘rbffi_thread_blocking_region’
     rbffi_thread_blocking_region(call_blocking_function, data, (void *) -1, NULL);
     ^
linking shared-object ffi_c.so

current directory: /home/anatol/sources/vagrant/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.10/ext/ffi_c
make "DESTDIR=" install
/usr/bin/install -c -m 0755 ffi_c.so ./.gem.20160108-18494-1q1ppro