ERROR: Error installing ffi: ERROR: Failed to build gem native extension

Question

Got the DevKit installed and re-ran the ffi install….got this as an output:

C:\Documents and Settings\******>gem install ffi
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
ERROR:  Error installing ffi:
        ERROR: Failed to build gem native extension.

        C:/Ruby192/bin/ruby.exe extconf.rb
checking for ffi.h... no
checking for ffi.h in /usr/local/include... no
checking for rb_thread_blocking_region()... yes
checking for ruby_thread_has_gvl_p()... yes
checking for ruby_native_thread_p()... yes
checking for rb_thread_call_with_gvl()... yes
creating extconf.h
creating Makefile
make
C:/Ruby192/bin/ruby -e "puts 'EXPORTS', 'Init_ffi_c'"  > ffi_c-i386-mingw32.def
gcc -I. -IC:/Ruby192/include/ruby-1.9.1/i386-mingw32 -I/C/Ruby192/include/ruby-1
.9.1/ruby/backward -I/C/Ruby192/include/ruby-1.9.1 -I. -DRUBY_EXTCONF_H=\"extcon
f.h\"    -O3 -g -Wextra -Wno-unused-parameter -Wno-parentheses -Wpointer-arith -
Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-declaration-a
fter-statement   -o AbstractMemory.o -c AbstractMemory.c
In file included from AbstractMemory.c:28:0:
compat.h:65:20: warning: extra tokens at end of #ifndef directive
compat.h:69:24: warning: extra tokens at end of #ifndef directive
In file included from AbstractMemory.h:29:0,
                 from AbstractMemory.c:29:
Types.h:68:17: fatal error: ffi.h: No such file or directory
compilation terminated.
make: *** [AbstractMemory.o] Error 1 

Gem files will remain installed in C:/Ruby192/lib/ruby/gems/1.9.1/gems/ffi-1.0.1
0 for inspection.
Results logged to C:/Ruby192/lib/ruby/gems/1.9.1/gems/ffi-1.0.10/ext/ffi_c/gem_m
ake.out
_________________________________________________________________________________

Not sure how to deal with this issue. Kindly help.

Answer 1

The gem install ffi fails due to the gem trying to build a bundled copy of libffi, which does not work due to assumptions that /usr/bin/env exists and too old libffi copy.

However, you can build the ffi gem against the system libffi - install the packages:

apt install clang make ruby-dev libffi-dev

After that the ffi gem should build:

gem install ffi