Compiling OpenFST for iOS giving casting errors

Question

I am trying to compile OpenFST for iOS, here is where make is failing:

cd openfst-1.6.5/src/lib
/Applications/Xcode.app/Contents/Developer/usr/bin/g++ 
  -DHAVE_CONFIG_H 
  -I./../include 
  -I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/include/c++/4.2.1/ 
  -I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/include/ 
  -miphoneos-version-min=8.1 
  -arch armv7 
  -fno-exceptions 
  -funsigned-char 
  -pipe 
  -no-cpp-precomp 
  -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk 
  -std=c++11 
  -MT compat.lo -MD -MP -MF .deps/compat.Tpo -c compat.cc -o compat.o

Its throwing many similar errors, like these

/../iPhoneOS.sdk/usr/include/c++/4.2.1/cwchar:212:12: 
  error: cannot initialize return object of type
  'wchar_t *' with an rvalue of type 'const wchar_t *'
{ return wcschr(const_cast<const wchar_t*>(__p), __c); }
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/../iPhoneOS.sdk/usr/include/c++/4.2.1/cwchar:218:12: 
  error: cannot initialize return object of type
  'wchar_t *' with an rvalue of type 'const wchar_t *'
{ return wcspbrk(const_cast<const wchar_t*>(__s1), __s2); }
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/../usr/include/c++/v1/tuple:1352:22: 
error: C++ requires a type specifier for all declarations
pair<_T1, _T2>::pair(piecewise_construct_t,
                     ^
/../usr/include/c++/v1/tuple:1351:1: 
error: declarator requires an identifier
inline _LIBCPP_INLINE_VISIBILITY
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I feel I am using the wrong c++ version here or something?

Answer 1

If c++/4.2.1 in your traceback means GCC 4.2.1, this is a positively ancient compiler suite (11 years old). The OpenFst README says it requires GCC 4.7 or greater. (This is presumably for C++11 and C99 support.) I don't know how to map XCode versions onto Clang compiler versions (and which Clang versions have substantial support for C++11) but I imagine that's documented somewhere.

FWIW I am running OpenFst on Linux + armv7 + GCC 5.4.0 (a cheapo Chromebook + Crouton) as we speak, so I doubt ARM support is the issue.