fix: don't treat compiler warnings as errors while compiling the C co…

…re, refs #654

setup.py

@@ -254,6 +254,11 @@ def _compile_in(
         # No need to build tests
         args.append("-DBUILD_TESTING=OFF")
 
+        # Do not treat compilation warnings as errors in case someone is trying
+        # to "pip install" igraph in an environment for which we don't provide
+        # wheels and the compiler complains about harmless things
+        args.append("-DIGRAPH_WARNINGS_AS_ERRORS=OFF")
+
         # Set install directory during config step instead of install step in order
         # to avoid having the architecture name in the LIBPATH (e.g. lib/x86_64-linux-gnu)
         args.append("-DCMAKE_INSTALL_PREFIX=" + str(install_folder))