rvm_ruby_make.log

+__rvm_make:0> make -j 1
	CC = gcc
	LD = ld
	LDSHARED = gcc -dynamiclib
	CFLAGS = -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -Wdivision-by-zero -Wdeprecated-declarations -Wextra-tokens   -fno-common -pipe 
	XCFLAGS = -D_FORTIFY_SOURCE=2 -fstack-protector -fno-strict-overflow -fvisibility=hidden -DRUBY_EXPORT
	CPPFLAGS = -I/usr/local/opt/libyaml/include -I/usr/local/opt/readline/include -I/usr/local/opt/libksba/include -I/usr/local/opt/openssl/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -D_DARWIN_UNLIMITED_SELECT -D_REENTRANT   -I. -I.ext/include/x86_64-darwin17 -I./include -I.
	DLDFLAGS = -Wl,-undefined,dynamic_lookup -Wl,-multiply_defined,suppress -L/usr/local/opt/libyaml/lib -L/usr/local/opt/readline/lib -L/usr/local/opt/libksba/lib -L/usr/local/opt/openssl/lib -install_name /Users/jun/.rvm/rubies/ruby-2.3.4/lib/libruby.2.3.0.dylib -compatibility_version 2.3 -current_version 2.3.4  -fstack-protector -Wl,-u,_objc_msgSend -framework CoreFoundation  -fstack-protector -Wl,-u,_objc_msgSend -framework CoreFoundation  
	SOLIBS = -lpthread -ldl -lobjc 
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.1.0 (clang-902.0.39.2)
Target: x86_64-apple-darwin17.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
translating probes probes.d
. ./vm_opts.h
compiling main.c
compiling dmydln.c
compiling miniinit.c
compiling dmyext.c
compiling miniprelude.c
compiling array.c
compiling bignum.c
compiling class.c
compiling compar.c
compiling complex.c
compiling dir.c
compiling dln_find.c
compiling encoding.c
compiling enum.c
compiling enumerator.c
compiling error.c
compiling eval.c
eval.c:763:8: warning: unused variable 'mid' [-Wunused-variable]
    ID mid = me->called_id;
       ^
1 warning generated.
compiling load.c
compiling proc.c
compiling file.c
file.c:23:10: fatal error: 'CoreFoundation/CFString.h' file not found
#include <CoreFoundation/CFString.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
make: *** [file.o] Error 1
+__rvm_make:0> return 2

Did you ever figure out a solution for this? I'm trying to switch to version 2.3.1 of ruby and it is not working. I am using rbenv on OSX Mojave 10.14. I have the exact same error "fatal error: 'CoreFoundation/CFString.h' file not found"