Update python-config invocation in Makefile

lava · lava · commit bf2be7108208 · 2020-05-02T16:55:11.000+02:00
Since the new Ubuntu 20.04  LTS version is shipping
python3.8 as the default python, update the Makefile
to use that as default and more importantly fix the
python-config invocation to work with all python
versions.
diff --git a/Makefile b/Makefile
@@ -2,11 +2,14 @@
 CXXFLAGS += -std=c++11 -Wno-conversion
 
 # Default to using system's default version of python
-PYTHON_BIN     ?= python
+PYTHON_BIN     ?= python3
 PYTHON_CONFIG  := $(PYTHON_BIN)-config
 PYTHON_INCLUDE ?= $(shell $(PYTHON_CONFIG) --includes)
 EXTRA_FLAGS    := $(PYTHON_INCLUDE)
-LDFLAGS        += $(shell $(PYTHON_CONFIG) --libs)
+# NOTE: Since python3.8, the correct invocation is `python3-config --libs --embed`. 
+# So of course the proper way to get python libs for embedding now is to
+# invoke that, check if it crashes, and fall back to just `--libs` if it does.
+LDFLAGS        += $(shell if $(PYTHON_CONFIG) --libs --embed >/dev/null; then $(PYTHON_CONFIG) --libs --embed; else $(PYTHON_CONFIG) --libs; fi)
 
 # Either finds numpy or set -DWITHOUT_NUMPY
 EXTRA_FLAGS     += $(shell $(PYTHON_BIN) $(CURDIR)/numpy_flags.py)
