Ninja not found by CMake

Question

I'm trying to build some code I got from GitHub using CMake, but keep getting the followings errors:

CMake Error: CMake was unable to find a build program corresponding to "Ninja".  CMAKE_MAKE_PROGRAM is not set.  You probably need to select a different build tool.
CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly.
Missing variable is:
CMAKE_C_COMPILER_ENV_VAR
CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly.
Missing variable is:
CMAKE_C_COMPILER
CMake Error: Could not find cmake module file:/golang/project/src/github.com/devsisters/goquic/libquic/build/debug/CMakeFiles/2.8.11/CMakeCCompiler.cmake
CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly.
Missing variable is:
CMAKE_CXX_COMPILER_ENV_VAR
CMake Error: Error required internal CMake variable not set, cmake may be not be built correctly.
Missing variable is:
CMAKE_CXX_COMPILER
CMake Error: Could not find cmake module file:/golang/project/src/github.com/devsisters/goquic/libquic/build/debug/CMakeFiles/2.8.11/CMakeCXXCompiler.cmake
-- Configuring incomplete, errors occurred!

How do I set these variables correctly?

I used a ./build_libs.sh file that came with the GitHub code to build this.

Answer 1

The script you are executing uses the CMake Ninja generator. For that to work you need Ninja on the path. On most Linux distributions you can install it from a package.

Ubuntu: ninja-build

openSUSE: ninja

If you can't find it for your distribution, you have to download it and add its location to the path environment variable.

Answer 2

My solution: symlink "ninja-build" to "ninja".

# ln -s /usr/bin/ninja /usr/bin/ninja-build

This only works on very old versions of CMake, which I will explain below.

I had already dropped my fresh "ninja" binary into /usr/bin and checked it had 0755 permissions. I was stumped until I ran an strace on the generator command.

# strace cmake -GNinja .. | grep -i ninja
access("ninja-build", R_OK)             = -1 ENOENT (No such file or directory)
access("/usr/local/sbin/ninja-build", R_OK) = -1 ENOENT (No such file or directory)
access("/usr/local/bin/ninja-build", R_OK) = -1 ENOENT (No such file or directory)
access("/sbin/ninja-build", R_OK)       = -1 ENOENT (No such file or directory)
access("/bin/ninja-build", R_OK)        = -1 ENOENT (No such file or directory)
access("/usr/sbin/ninja-build", R_OK)   = -1 ENOENT (No such file or directory)
access("/usr/bin/ninja-build", R_OK)    = -1 ENOENT (No such file or directory)
access("/opt/texlive/2016/bin/i386-linux/ninja-build", R_OK) = -1 ENOENT (No such file or directory)
access("/root/bin/ninja-build", R_OK)   = -1 ENOENT (No such file or directory)

It was looking for "ninja-build", not "ninja"!

I use CMake with Ninja extensively at work and at home, on Windows and Linux. So why haven't I seen this bug before?

Well... in this instance I'm using a very old version of CMake, version 2.8.12. It's so old it's almost fossilised. So presumably it's either a CMake bug which was fixed later, or the Ninja project changed the name of the binary at some point.

Answer 3

If ninja really exists in $PATH and it still does not work, you should check the permission of the executable file via ls -l /PATH/TO/NINJA. Make sure others have read and execute permissions (like '-rwxr-xr-x').

See also: 0013910: Ninja generator initialization fails if /usr/bin/ninja is not world-readable