macOS: Undefined symbols for architecture arm64: "_libiconv", referenced from: (anonymous namespace)::convertStringCharsetIconv

[clanmills]

Apple M1 processors are failing to link the iConv library distributed in macOS SDK 11.3. The full message is:

[ 47%] Building CXX object src/CMakeFiles/exiv2lib.dir/bmffimage.cpp.o
[ 48%] Linking CXX shared library ../lib/libexiv2.dylib
Undefined symbols for architecture arm64:
  "_libiconv", referenced from:
      (anonymous namespace)::convertStringCharsetIconv(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&, char const*, char const*) in convert.cpp.o
  "_libiconv_close", referenced from:
      (anonymous namespace)::convertStringCharsetIconv(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&, char const*, char const*) in convert.cpp.o
  "_libiconv_open", referenced from:
      (anonymous namespace)::convertStringCharsetIconv(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&, char const*, char const*) in convert.cpp.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [lib/libexiv2.0.27.5.2.dylib] Error 1
make[1]: *** [src/CMakeFiles/exiv2lib.dir/all] Error 2
make: *** [all] Error 2
565 rmills@rmillsm1:~/gnu/github/exiv2/foo/0.27-maintenance/build $ 

The work-around is:

diff --git a/cmake/findDependencies.cmake b/cmake/findDependencies.cmake
index ec3a43f5..625f825a 100644
--- a/cmake/findDependencies.cmake
+++ b/cmake/findDependencies.cmake
@@ -53,6 +53,15 @@ if (EXIV2_ENABLE_NLS)
 endif( )
 
 find_package(Iconv)
+# Don't use Iconv on macOS M1.  Linker fails because SDK libiconv not been built for arm64
+if ( APPLE )
+       EXECUTE_PROCESS( COMMAND uname -m COMMAND tr -d '\n' OUTPUT_VARIABLE ARCHITECTURE )
+       if ( ${ARCHITECTURE} STREQUAL arm64 )
+       set(ICONV_FOUND 0)
+       message ( "-- ICONV ignored on Apple M1 processor" )
+       endif()
+endif()
+
 if( ICONV_FOUND )
     message ( "-- ICONV_INCLUDE_DIR : " ${Iconv_INCLUDE_DIR} )
     message ( "-- ICONV_LIBRARIES : " ${Iconv_LIBRARY} )

When this patch is applied, the outputfrom cmake is:

-- Performing Test Iconv_IS_BUILT_IN
-- Performing Test Iconv_IS_BUILT_IN - Failed
-- Found Iconv: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/lib/libiconv.tbd  
-- ICONV ignored on Apple M1 processor

I don't think this code should be added permanently as it would disable libiconv permanently on the M1. Presumably Apple will fix the SDK. I haven't reported this to Apple. So let's leave this issue open and "never fix" as the issue should disappear in time.

[clanmills]

Here's another work-around. Delete the file in the SDK that doesn't work, rerun cmake and build!

540 rmills@rmillsm1:~/gnu/github/exiv2/0.27-maintenance/build $ sudo rm -rf /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk/usr/lib/libiconv.tbd 
541 rmills@rmillsm1:~/gnu/github/exiv2/0.27-maintenance/build $ cd .. ; rm -rf build ; mkdir build ; cd build
542 rmills@rmillsm1:~/gnu/github/exiv2/0.27-maintenance/build $ cmake .. -DEXIV2_ENABLE_BMFF=1
543 rmills@rmillsm1:~/gnu/github/exiv2/0.27-maintenance/build $ make
.......
544 rmills@rmillsm1:~/gnu/github/exiv2/0.27-maintenance/build $ 

I'm going to close this. The issue has been record in the project history. It's not an Exiv2 issue.

[clanmills]

Apple's SDK works. Building libiconv from source and installing it in /usr/local/lib is causing this linking issue. See: #1915 (comment)