https://fedoraproject.org/wiki/Changes/CMake_to_do_out-of-source_builds

libarcus.spec

@@ -19,6 +19,9 @@ BuildRequires:  cmake
 BuildRequires:  gcc-c++
 BuildRequires:  git-core
 
+# Get Fedora 33++ behavior on anything older
+%undefine __cmake_in_source_build
+
 %description
 Arcus library contains C++ code and Python 3 bindings for creating a socket in
 a thread and using this socket to send and receive messages based on the
@@ -60,11 +63,11 @@ between Cura and its backend and similar code.
 sed -i 's/Python3_SITELIB/Python3_SITEARCH/' cmake/SIPMacros.cmake
 
 %build
-%{cmake} -DBUILD_EXAMPLES:BOOL=OFF -DCMAKE_SKIP_RPATH:BOOL=ON .
-%make_build
+%cmake -DBUILD_EXAMPLES:BOOL=OFF -DCMAKE_SKIP_RPATH:BOOL=ON .
+%cmake_build
 
 %install
-%make_install
+%cmake_install
 
 %files
 %license LICENSE