cmake fails on clean install

[martinduke]

In Ubuntu:
ietf@ietf-VirtualBox:~/picotls$ cmake .
-- The CXX compiler identification is unknown
-- Check for working CXX compiler: /usr/bin/cmake
-- Check for working CXX compiler: /usr/bin/cmake -- broken
CMake Error at /usr/share/cmake-3.16/Modules/CMakeTestCXXCompiler.cmake:53 (message):
The C++ compiler

"/usr/bin/cmake"

is not able to compile a simple test program.

It fails with the following output:

Change Dir: /home/ietf/picotls/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_d38b4/fast && /usr/bin/make -f CMakeFiles/cmTC_d38b4.dir/build.make CMakeFiles/cmTC_d38b4.dir/build
make[1]: Entering directory '/home/ietf/picotls/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_d38b4.dir/testCXXCompiler.cxx.o
/usr/bin/cmake     -o CMakeFiles/cmTC_d38b4.dir/testCXXCompiler.cxx.o -c /home/ietf/picotls/CMakeFiles/CMakeTmp/testCXXCompiler.cxx
CMake Error: The source directory "/home/ietf/picotls/CMakeFiles/CMakeTmp/-c" does not exist.
Specify --help for usage, or press the help button on the CMake GUI.
make[1]: *** [CMakeFiles/cmTC_d38b4.dir/build.make:66: CMakeFiles/cmTC_d38b4.dir/testCXXCompiler.cxx.o] Error 1
make[1]: Leaving directory '/home/ietf/picotls/CMakeFiles/CMakeTmp'
make: *** [Makefile:121: cmTC_d38b4/fast] Error 2

CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
CMakeLists.txt:4 (PROJECT)

-- Configuring incomplete, errors occurred!
See also "/home/ietf/picotls/CMakeFiles/CMakeOutput.log".
See also "/home/ietf/picotls/CMakeFiles/CMakeError.log".

[martinduke]

rm -rf CMakeFiles
rm CMakeCache.txt
cmake .

did the trick