fix SWIG_DOXYGEN; add SWIG_PY_DOXYGEN

Makefile

@@ -140,7 +140,7 @@ else
 	@echo
 endif
 
-print-%  : ; @echo $* = $($*)
+print-%  : ; @echo $* = \'$($*)\'
 
 .PHONY: FORCE
 FORCE:

makefiles/Makefile.python.mk

@@ -36,6 +36,15 @@ PYTHON3_CFLAGS := -DPY3
 endif
 endif
 
+# Set -doxygen tag for swig if possible
+ifeq ("$(SWIG_VERSION)","4.0.0")
+  ifneq ("$(PYTHON_EXECUTABLE)","")
+    ifeq ($(shell "$(PYTHON_EXECUTABLE)" -c "from sys import version_info as v; print (str(v[0]))"),3)
+SWIG_PY_DOXYGEN = -doxygen
+    endif
+  endif
+endif
+
 # All libraries and dependecies
 PYALGORITHMS_LIBS = $(LIB_DIR)/_pywrapknapsack_solver.$(SWIG_PYTHON_LIB_SUFFIX)
 PYGRAPH_LIBS = $(LIB_DIR)/_pywrapgraph.$(SWIG_PYTHON_LIB_SUFFIX)

makefiles/Makefile.third_party.unix.mk

@@ -764,12 +764,16 @@ SWIG_BINARY = $(shell $(WHICH) $(UNIX_SWIG_BINARY))
 SWIG_VERSION = $(shell $(SWIG_BINARY) -version | grep Version | cut -d " " -f 3)
 ifeq ("$(SWIG_VERSION)","4.0.0")
 SWIG_DOXYGEN = -doxygen
-ifneq ($(PYTHON_EXECUTABLE),)
-ifeq ($(shell "$(PYTHON_EXECUTABLE)" -c "from sys import version_info as v; print (str(v[0]))"),3)
-SWIG_PY_DOXYGEN = -doxygen
 endif
+
+test_doxy:
+ifneq ("$(PYTHON_EXECUTABLE)","")
+	echo "Pass 1"
+ifeq ($(shell "$(PYTHON_EXECUTABLE)" -c "from sys import version_info as v; print (str(v[0]))"),3)
+	echo "SWIG_PY_DOXYGEN = -doxygen"
 endif
 endif
+	echo \'$(shell "$(PYTHON_EXECUTABLE)" -c "from sys import version_info as v; print (str(v[0]))")\'
 
 .PHONY: clean_third_party # Clean everything. Remember to also delete archived dependencies, i.e. in the event of download failure, etc.
 clean_third_party: