Updating CMake (seems to have) broke my program

Question

I updated from CMake 3.6 to whatever the latest version is (3.12.0-rc2) and now one of my programs won't compile.

The weird thing is, the error message shows undefined symbols from in the standard library itself. Here's the error message:

Undefined symbols for architecture x86_64:
  "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::basic_string(char const*)", referenced from:
      GetName() in ncc.cpp.o
      Expression() in ncc.cpp.o
      Term() in ncc.cpp.o
      GetNum() in ncc.cpp.o
  "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::basic_string()", referenced from:
      GetName() in ncc.cpp.o
      GetNum() in ncc.cpp.o
  "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::operator+=(char)", referenced from:
      GetName() in ncc.cpp.o
      GetNum() in ncc.cpp.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[2]: *** [ncc] Error 1
make[1]: *** [CMakeFiles/ncc.dir/all] Error 2
make: *** [all] Error 2

How do I fix this? Do I need to link to a different version of the standard library? And if so, how I tell CMake that?

Here's my CMakeLists.txt file:

cmake_minimum_required(VERSION 3.0)

project(ncc)

add_definitions(-std=c++14)

add_subdirectory(${CMAKE_SOURCE_DIR}/src/)

add_executable(ncc ${CompSource})
add_executable(ncc-opt ${OptSource})
add_executable(nci ${IntSource})

I tried it with the add_definitions line and without it, which didn't seem to make a difference.

This is the relevant output from running make VERBOSE=1:

Scanning dependencies of target ncc
/Applications/Xcode.app/Contents/Developer/usr/bin/make -f CMakeFiles/ncc.dir/build.make CMakeFiles/ncc.dir/build
[ 83%] Building CXX object CMakeFiles/ncc.dir/src/ncc.cpp.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++    -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk   -std=c++14 -o CMakeFiles/ncc.dir/src/ncc.cpp.o -c /Users/nepps/Dropbox/Projects/ncc/src/ncc.cpp
[100%] Linking CXX executable ncc
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/ncc.dir/link.txt --verbose=1
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++   -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names  CMakeFiles/ncc.dir/src/ncc.cpp.o  -o ncc 
Undefined symbols for architecture x86_64:
(same errors as above)

Feel free to comment if you need more information. I'm using a MacBook pro running MacOS 10.13.3.

Maybe the default c++ standard version has changed, are you selecting explicitely a version of the c++ standard in the CMakeFile, or are you letting CMake chose one? (please include the CMakeFile) — Olivier Sohn, Jul 04 '18 at 21:32
I don't think that's the issue, as I tried with and without the `-std=c++1y` line. @OlivierSohn — Dovahkiin, Jul 05 '18 at 03:26
Use a verbose build option, find out what commands actually run at compilation and link stages, and proceed from there. — n. m. could be an AI, Jul 05 '18 at 04:01
@Dovahkiin according to https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html#index-std-108 `c++1y` is deprecated, you should probably use `c++14` instead — Olivier Sohn, Jul 05 '18 at 07:04
Okay, I tried it, but it didn't change the error. @OlivierSohn — Dovahkiin, Jul 06 '18 at 12:08
Maybe some compilation unit (or some library you link with) has seen headers from a different version of the C++ (there were changes on basic_string in c++17, this is what makes me think about that). — Olivier Sohn, Jul 06 '18 at 13:42
https://stackoverflow.com/questions/27508451/cmake-error-undefined-symbols-for-x86-64 — sailfish009, Jul 08 '18 at 02:43
What would help here is a minimal reproducible example. Also, maybe a bit naively, have you removed all (temporary) build files of the porject after updating? — Tom de Geus, Jul 14 '18 at 12:23

score -1 · Accepted Answer · answered Jul 09 '18 at 01:06

-1

Well, I'm not sure why it worked, but all of the functions in the program were marked static and removing that made the errors go away. Go figure.

answered Jul 09 '18 at 01:06

Dovahkiin

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Updating CMake (seems to have) broke my program

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