Add support for building with Python 3

[cbiesinger]

Summary

LLDB supports Python 3 now.

[mgorny]

llvm/CMakeLists.txt

645

Wouldn't the correct thing to do be removing the list altogether?

[cbiesinger]

llvm/CMakeLists.txt

645

Apparently not; if I do that CMake still finds Python 2.7.

• Found PythonLibs: /usr/lib/x86_64-linux-gnu/libpython2.7.so (found version "2.7.16")

[mgorny]

llvm/CMakeLists.txt

645

In that case, you should specify at least 3.7 as well. Maybe 3.5 if it works.

[cbiesinger]

Add 3.7 and 3.5

[cbiesinger]

llvm/CMakeLists.txt

645

OK, done. (I don't have 3.5 to test but have no reason to assume it won't work)

[thakis]

lgtm

[pree-jackie]

Hey guys, I get cmake error at configuration time " Found incompatible python interpreter version and python libraries version". I have both python 2.7 and python 3.6, cmake now finds python interpreter version 3.6 and python libs 2.7, hence the incompatibility. How I can rectify this?

[pree-jackie]

I reverse the list as 2.7 3.5 3.6 3.7 it fixes the issue, but I don't know whether it is correct or not.

[cbiesinger]

pree-jackie: My guess is that you have python2.7-dev installed but not python3.6-dev -- does it work if you install that one?

llvm/CMakeLists.txt

if(WIN32 OR CYGWIN)
   endif()
 else()
   set(LLVM_ENABLE_PLUGINS_default ${LLVM_ENABLE_PIC})
 endif()
 option(LLVM_ENABLE_PLUGINS "Enable plugin support" ${LLVM_ENABLE_PLUGINS_default})
 
 include(HandleLLVMOptions)
 
-# Verify that we can find a Python 2 interpreter.  Python 3 is unsupported.
-# FIXME: We should support systems with only Python 3, but that requires work
-# on LLDB.
-set(Python_ADDITIONAL_VERSIONS 2.7)
+# We support both Python 2 and 3.
+set(Python_ADDITIONAL_VERSIONS 3.7 3.6 3.5 2.7)
 include(FindPythonInterp)
 if( NOT PYTHONINTERP_FOUND )
   message(FATAL_ERROR
 "Unable to find Python interpreter, required for builds and testing.
 
 Please install Python or specify the PYTHON_EXECUTABLE CMake variable.")
 endif()