安装 FFI Gem 时出错 - [-Werror,-Wimplicit-function-declaration]

Question

Specifically, the error looks like this:

Function.c:563:9: error: implicit declaration of function 'rb_thread_call_without_gvl' is invalid in
C99 [-Werror,-Wimplicit-function-declaration]
        rb_thread_call_without_gvl(async_cb_wait, &w, async_cb_stop, &w);
        ^
Function.c:563:9: note: did you mean 'rb_thread_call_with_gvl'?
Function.c:102:14: note: 'rb_thread_call_with_gvl' declared here
extern void *rb_thread_call_with_gvl(void *(*func)(void *), void *data1);
             ^
Function.c:948:17: warning: 'ffi_prep_closure' is deprecated [-Wdeprecated-declarations]
    ffiStatus = ffi_prep_closure(code, &fnInfo->ffi_cif, callback_invoke, closure);
                ^
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/ffi/ffi.h:350:18: note:
'ffi_prep_closure' has been explicitly marked deprecated here
  __attribute__((deprecated))

I've been trying to install an older version of FFI v'1.9.18' using Ruby 2.3.6.

Answer 1

Found the solution: gem install ffi -v '1.9.18' -- --with-cflags="-Wno-error=implicit-function-declaration"

Got the solution from this: StackOverflow