How do you build examples?

[wusspuss]

I get this error

bash-5.1$ cd libdatachannel/examples/media-receiver
bash-5.1$ cmake -B build
CMake Warning (dev) in CMakeLists.txt:
  No project() command is present.  The top-level CMakeLists.txt file must
  contain a literal, direct call to the project() command.  Add a line of
  code such as

    project(ProjectName)

  near the top of the file, but after cmake_minimum_required().

  CMake is pretending there is a "project(Project)" command on the first
  line.
This warning is for project developers.  Use -Wno-dev to suppress it.

-- The C compiler identification is GNU 11.2.0
-- The CXX compiler identification is GNU 11.2.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE  
-- Configuring done
CMake Error at CMakeLists.txt:16 (add_executable):
  Target "datachannel-media-receiver" links to target
  "LibDataChannel::LibDataChannel" but the target was not found.  Perhaps a
  find_package() call is missing for an IMPORTED target, or an ALIAS target
  is missing?


CMake Error at CMakeLists.txt:16 (add_executable):
  Target "datachannel-media-receiver" links to target
  "nlohmann_json::nlohmann_json" but the target was not found.  Perhaps a
  find_package() call is missing for an IMPORTED target, or an ALIAS target
  is missing?


-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.

libdatachannel was installed from source like:

$ git clone https://github.com/paullouisageneau/libdatachannel.git
$ cd libdatachannel
$ git submodule update --init --recursive --depth 1
$ cmake -B build -DUSE_GNUTLS=0 -DUSE_NICE=0 -DCMAKE_BUILD_TYPE=Release
$ cd build
$ make -j4
$ make install

and now finds itself under /usr/local, it's definitely there:

$ find /usr/local -name *datachannel*
/usr/local/lib/libdatachannel.so.0.18.5
/usr/local/lib/libdatachannel.so
/usr/local/include/rtc/datachannel.hpp

So what can the issue be? Why does it have trouble finding it?

[paullouisageneau]

Examples are built when you run cmake at top-level. They would need libdatachannel and nlohmann_json to be installed and find_package lines for both libraries to compile as standalone.

Simply run:

$ cmake -B build -DUSE_GNUTLS=0 -DUSE_NICE=0 -DCMAKE_BUILD_TYPE=Release
$ cd build
$ make -j4

and examples will be built in build/examples.

[wusspuss]

Also, I found you can just do g++ -ldatachannel ./main.cpp

[paullouisageneau]

Yes once the library is installed you can link against it like any system library.