CMake Error at CMakeLists.txt:35 (add_subdirectory)

[0ric1]

After downloading the zip release 3.1 and unpacking I did md build and cd build and called cmake .. and got the following error:

-- Building for: Visual Studio 15 2017
-- The CXX compiler identification is MSVC 19.16.27030.1
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Professional/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Professional/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:35 (add_subdirectory):
The source directory

T:/temp/utfcpp31/extern/gtest

does not contain a CMakeLists.txt file.

-- Configuring incomplete, errors occurred!
See also "T:/temp/utfcpp31/build/CMakeFiles/CMakeOutput.log".

It seems gtest is missing.

[matlo607]

You should either disable the build of tests using -DUTF8_TESTS=off or run git submodule update --init at the root of the project to clone googletest's repository into extern/gtest.

[nemtrif]

The zip does not contain the google test library. It's really intended for CI runs only.

[0ric1]

I would expect that googletest is included in the zip too or downloaded automatically, other libraries contain everything to build too or download on demand e.g. googlebenchmark https://github.com/google/benchmark that adds googletest on demand with cmake ExternalProject_Add .

[matlo607]

@blonder : including the sources of a third party in a project is, in my opinion, not a good idea for several reasons (build systems' incompatibility, forking prevent you from getting update, new features and bug fixes easily, ...).

Using a package manager to pull the dependencies is a preferable approach. C++ does not offer an official one yet. I would advise you to have a look at Conan.

git-submodule has a good reason to exist for big projects. That allows to add modularity to the project and also avoid to hit Git's performance issues when you have millions of files. This approach has an important drawback, it only works if the build systems of the projects are the same (unless you write an adapter yourself, good luck with that).

ExternalProject_Add is not a good idea too. CMake is a build system, not a package manager. People want to do everything with it, I think it's an error.