# Build problem (unknown \_libiconv symbols) on macOS (using MacPorts)

**URL:** <https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796>\
**Category:** Support\
**Created:** [January 9, 2018, 3:49pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796 "2018-01-09T15:49:47Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![hmeine](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/hmeine/32/1060_2.png) [@hmeine](https://discourse.slicer.org/u/hmeine)\
**Post date:** [January 9, 2018, 3:49pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796/1 "2018-01-09T15:49:47Z")

</div>

I am trying to compile Slicer on macOS 10.12.6 with XCode 9.1. Homebrew is _not_ installed, I am using MacPorts.

My SuperBuild fails in `DCMTK-build`, with

> [2%] Linking CXX shared library …/…/lib/libofstd.dylib  
> Undefined symbols for architecture x86\_64:  
> “\_libiconv”, referenced from:  
> OFCharacterEncoding::Implementation::convert(OFString&, char const\*, unsigned long) in ofchrenc.cc.o  
> “\_libiconv\_close”, referenced from:  
> OFCharacterEncoding::Implementation::~Implementation() in ofchrenc.cc.o  
> “\_libiconv\_open”, referenced from:  
> OFCharacterEncoding::Implementation::create(OFString const&, OFString const&, OFCondition&) in ofchrenc.cc.o  
> “\_libiconvctl”, referenced from:  
> OFCharacterEncoding::Implementation::getConversionFlags() const in ofchrenc.cc.o  
> OFCharacterEncoding::Implementation::setConversionFlags(unsigned int) in ofchrenc.cc.o  
> “\_locale\_charset”, referenced from:  
> OFCharacterEncoding::Implementation::getLocaleEncoding() in ofchrenc.cc.o  
> ld: symbol(s) not found for architecture x86\_64  
> clang: error: linker command failed with exit code 1 (use -v to see invocation)  
> make[5]: \*\*\* [lib/libofstd.3.6.2.dylib] Error 1  
> make[4]: \*\*\* [ofstd/libsrc/CMakeFiles/ofstd.dir/all] Error 2  
> make[3]: \*\*\* [all] Error 2  
> make[2]: \*\*\* [DCMTK-prefix/src/DCMTK-stamp/DCMTK-build] Error 2  
> make[1]: \*\*\* [CMakeFiles/DCMTK.dir/all] Error 2

Does that look familiar to anyone?

---

<div class="post-metadata">

**Author:** ![hmeine](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/hmeine/32/1060_2.png) [@hmeine](https://discourse.slicer.org/u/hmeine)\
**Post date:** [January 9, 2018, 4:08pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796/2 "2018-01-09T16:08:17Z")

</div>

@ihnorton suggested that it could be the wrong libiconv (probably from MacPorts) being picked up – that sounds reasonable. I’m investigating.

---

<div class="post-metadata">

**Author:** ![hmeine](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/hmeine/32/1060_2.png) [@hmeine](https://discourse.slicer.org/u/hmeine)\
**Post date:** [January 9, 2018, 4:43pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796/3 "2018-01-09T16:43:51Z")

</div>

Ok, so from [https://issues.slicer.org/view.php?id=2006](https://issues.slicer.org/view.php?id=2006) I thought that libiconv would not be needed and deactivated. In CMake, I can see that `DCMTK_WITH_ICONV` is disabled.

Still, I tried to `port deactivate libiconv`, confirming that I want to do that despite ~40 packages depend on it, but then CMake was one of these… 😉

There’s also a libiconv in /usr (macOS-provided, I assume), which gets picked up first when I enable `DCMTK_WITH_ICONV`. Building with `DCMTK_WITH_ICONV` and either the /usr or the /opt/local (MacPorts) version did not work, either. (Leading to the exact same linker error.)

So, back to square one: Why am I getting these missing symbols when `DCMTK_WITH_ICONV` is disabled, as it should be, in the first place?

---

<div class="post-metadata">

**Author:** ![hmeine](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/hmeine/32/1060_2.png) [@hmeine](https://discourse.slicer.org/u/hmeine)\
**Post date:** [January 9, 2018, 6:16pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796/4 "2018-01-09T18:16:30Z")

</div>

More info: I started the SuperBuild with

> cmake \  
> -DCMAKE\_OSX\_DEPLOYMENT\_TARGET=10.12 \  
> -DQT\_QMAKE\_EXECUTABLE=/opt/local/libexec/qt4/bin/qmake \  
> -DSlicer\_USE\_PYTHONQT\_WITH\_TCL=false \  
> $SRC\_DIR

and Qt is version 4.8.7\_5 (although that shouldn’t make a difference for dcmtk, AFAICS). I also tried a fresh build with `CMAKE_OSX_DEPLOYMENT_TARGET=10.11`, FWIW. CMake is 3.10.1.

On @che85’s machine with Sierra, but HomeBrew instead of MacPorts, we managed to compile the same code.

---

<div class="post-metadata">

**Author:** ![hmeine](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/hmeine/32/1060_2.png) [@hmeine](https://discourse.slicer.org/u/hmeine)\
**Post date:** [January 10, 2018, 8:32pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796/5 "2018-01-10T20:32:55Z")

</div>

@ihnorton and I debugged this further and ultimately found the culprit:

In the out-of-source build of `DCMTK/ofstd/libsrc/ofchrenc.cc`, the line

```auto
#include "dcmtk/config/osconfig.h"

```

picks up the wrong `osconfig.h` from `/opt/local/include` (MacPorts) which has ICONV enabled.

Now one solution would be to disable / remove that dcmtk. However, I wonder where the include path comes from, which is defined like this:

```auto
set(CMAKE_CXX_TARGET_INCLUDE_PATH
  "/opt/local/include"
  "config/include"
  "/Users/hmeine/Developer/MIC_OSS/Slicer/Slicer-SuperBuild-Debug/DCMTK/ofstd/include"
  "/Users/hmeine/Developer/MIC_OSS/Slicer/Slicer-SuperBuild-Debug/DCMTK/oflog/include"
  "/Users/hmeine/Developer/MIC_OSS/Slicer/Slicer-SuperBuild-Debug/DCMTK/dcmdata/include"
  "/Users/hmeine/Developer/MIC_OSS/Slicer/Slicer-SuperBuild-Debug/DCMTK/dcmimgle/include"
...

```

As you can see, the dcmtk build & source directories immediately follow the culprit, so why is that one in front?

Got it! `DCMTK_WITH_ICU` was enabled! Now I can build. Still, I wonder why this flag leads to the include path being _prepended_ instead of appended after the superbuild-paths. Maybe someone subscribed to dcmtk lists or involved in dcmtk and its CMake system would like to fix this?

---

<div class="post-metadata">

**Author:** ![ihnorton](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ihnorton/32/9_2.png) [@ihnorton](https://discourse.slicer.org/u/ihnorton)\
**Post date:** [September 13, 2018, 2:33pm UTC](https://discourse.slicer.org/t/build-problem-unknown-libiconv-symbols-on-macos-using-macports/1796/6 "2018-09-13T14:33:38Z")

</div>

Dropping a breadcrumb here so I can find this again next time I need it. Here is the explanation why ICU is not used:

- [https://github.com/Slicer/Slicer/pull/976#issuecomment-405286985](https://github.com/Slicer/Slicer/pull/976#issuecomment-405286985)
- [https://github.com/commontk/CTK/issues/178](https://github.com/commontk/CTK/issues/178)