diff -r 829117ae2e55 Makefile.pre.in
--- a/Makefile.pre.in	Tue Jul 19 16:46:09 2016 -0500
+++ b/Makefile.pre.in	Fri Jul 22 11:19:17 2016 +0200
@@ -223,6 +223,7 @@
 BUILDPYTHON=	python$(BUILDEXE)
 
 cross_compiling=@cross_compiling@
+PYTHON_FOR_GEN=@PYTHON_FOR_GEN@
 PYTHON_FOR_BUILD=@PYTHON_FOR_BUILD@
 _PYTHON_HOST_PLATFORM=@_PYTHON_HOST_PLATFORM@
 BUILD_GNU_TYPE=	@build@
@@ -340,7 +341,7 @@
 OPCODE_H_DIR= 	$(srcdir)/Include
 OPCODE_H_SCRIPT= $(srcdir)/Tools/scripts/generate_opcode_h.py
 OPCODE_H=	$(OPCODE_H_DIR)/opcode.h
-OPCODE_H_GEN=	@OPCODEHGEN@  $(OPCODE_H_SCRIPT) $(srcdir)/Lib/opcode.py $(OPCODE_H)
+OPCODE_H_GEN=	$(PYTHON_FOR_GEN) $(OPCODE_H_SCRIPT) $(srcdir)/Lib/opcode.py $(OPCODE_H)
 #
 ##########################################################################
 # AST
@@ -353,7 +354,7 @@
 ASDLGEN_FILES=	$(srcdir)/Parser/asdl.py $(srcdir)/Parser/asdl_c.py
 # Note that a build now requires Python to exist before the build starts.
 # Use "hg touch" to fix up screwed up file mtimes in a checkout.
-ASDLGEN=	@ASDLGEN@ $(srcdir)/Parser/asdl_c.py
+ASDLGEN=	$(PYTHON_FOR_GEN) $(srcdir)/Parser/asdl_c.py
 
 ##########################################################################
 # Python
@@ -882,7 +883,7 @@
 Objects/setobject.o: $(srcdir)/Objects/stringlib/eq.h
 
 $(OPCODETARGETS_H): $(OPCODETARGETGEN_FILES)
-	$(OPCODETARGETGEN) $(OPCODETARGETS_H)
+	$(PYTHON_FOR_GEN) $(OPCODETARGETGEN) $(OPCODETARGETS_H)
 
 Python/ceval.o: $(OPCODETARGETS_H) $(srcdir)/Python/ceval_gil.h
 
@@ -890,7 +891,7 @@
 
 Objects/typeobject.o: Objects/typeslots.inc
 Objects/typeslots.inc: $(srcdir)/Include/typeslots.h $(srcdir)/Objects/typeslots.py
-	$(PYTHON) $(srcdir)/Objects/typeslots.py < $(srcdir)/Include/typeslots.h > Objects/typeslots.inc
+	$(PYTHON_FOR_GEN) $(srcdir)/Objects/typeslots.py < $(srcdir)/Include/typeslots.h Objects/typeslots.inc
 
 ############################################################################
 # Header files
diff -r 829117ae2e55 Objects/typeslots.py
--- a/Objects/typeslots.py	Tue Jul 19 16:46:09 2016 -0500
+++ b/Objects/typeslots.py	Fri Jul 22 11:19:17 2016 +0200
@@ -1,32 +1,44 @@
 #!/usr/bin/python
-# Usage: typeslots.py < Include/typeslots.h > typeslots.inc
+# Usage: typeslots.py < Include/typeslots.h typeslots.inc
 
 import sys, re
 
-print("/* Generated by typeslots.py */")
-res = {}
-for line in sys.stdin:
-    m = re.match("#define Py_([a-z_]+) ([0-9]+)", line)
-    if not m:
-        continue
-    member = m.group(1)
-    if member.startswith("tp_"):
-        member = "ht_type."+member
-    elif member.startswith("am_"):
-        member = "as_async."+member
-    elif member.startswith("nb_"):
-        member = "as_number."+member
-    elif member.startswith("mp_"):
-        member = "as_mapping."+member
-    elif member.startswith("sq_"):
-        member = "as_sequence."+member
-    elif member.startswith("bf_"):
-        member = "as_buffer."+member
-    res[int(m.group(2))] = member
+def generate_typeslots(out=sys.stdout):
+    out.write("/* Generated by typeslots.py */\n")
+    res = {}
+    for line in sys.stdin:
+        m = re.match("#define Py_([a-z_]+) ([0-9]+)", line)
+        if not m:
+            continue
+        member = m.group(1)
+        if member.startswith("tp_"):
+            member = "ht_type."+member
+        elif member.startswith("am_"):
+            member = "as_async."+member
+        elif member.startswith("nb_"):
+            member = "as_number."+member
+        elif member.startswith("mp_"):
+            member = "as_mapping."+member
+        elif member.startswith("sq_"):
+            member = "as_sequence."+member
+        elif member.startswith("bf_"):
+            member = "as_buffer."+member
+        res[int(m.group(2))] = member
 
-M = max(res.keys())+1
-for i in range(1,M):
-    if i in res:
-        print("offsetof(PyHeapTypeObject, %s)," % res[i])
+    M = max(res.keys())+1
+    for i in range(1,M):
+        if i in res:
+            out.write("offsetof(PyHeapTypeObject, %s),\n" % res[i])
+        else:
+            out.write("0,\n")
+
+def main():
+    if len(sys.argv) == 2:
+        with open(sys.argv[1], "w") as f:
+            generate_typeslots(f)
     else:
-        print("0,")
+        generate_typeslots()
+
+if __name__ == "__main__":
+    main()
+
diff -r 829117ae2e55 configure
--- a/configure	Tue Jul 19 16:46:09 2016 -0500
+++ b/configure	Fri Jul 22 11:19:17 2016 +0200
@@ -680,9 +680,6 @@
 INSTALL_DATA
 INSTALL_SCRIPT
 INSTALL_PROGRAM
-OPCODEHGEN
-PYTHON
-ASDLGEN
 ac_ct_READELF
 READELF
 ARFLAGS
@@ -744,6 +741,7 @@
 SOVERSION
 VERSION
 PYTHON_FOR_BUILD
+PYTHON_FOR_GEN
 host_os
 host_vendor
 host_cpu
@@ -2996,6 +2994,56 @@
 # pybuilddir.txt will be created by --generate-posix-vars in the Makefile
 rm -f pybuilddir.txt
 
+for ac_prog in python$PACKAGE_VERSION python3 python
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_PYTHON_FOR_GEN+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$PYTHON_FOR_GEN"; then
+  ac_cv_prog_PYTHON_FOR_GEN="$PYTHON_FOR_GEN" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_PYTHON_FOR_GEN="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+PYTHON_FOR_GEN=$ac_cv_prog_PYTHON_FOR_GEN
+if test -n "$PYTHON_FOR_GEN"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PYTHON_FOR_GEN" >&5
+$as_echo "$PYTHON_FOR_GEN" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$PYTHON_FOR_GEN" && break
+done
+test -n "$PYTHON_FOR_GEN" || PYTHON_FOR_GEN="not-found"
+
+if test "$PYTHON_FOR_GEN" = not-found; then
+    PYTHON_FOR_GEN='@echo "Cannot generate $@, python not found !" && \
+    echo "To skip re-generation of $@ run <make touch> or <make -t $@>." && \
+    echo "Otherwise, set python in PATH and run configure or run <make PYTHON_FOR_GEN=python>." && false &&'
+fi
+
+
 if test "$cross_compiling" = yes; then
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for python interpreter for cross build" >&5
 $as_echo_n "checking for python interpreter for cross build... " >&6; }
@@ -6329,107 +6377,6 @@
 
 
 
-for ac_prog in python$PACKAGE_VERSION python3 python
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_PYTHON+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -n "$PYTHON"; then
-  ac_cv_prog_PYTHON="$PYTHON" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
-    ac_cv_prog_PYTHON="$ac_prog"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-PYTHON=$ac_cv_prog_PYTHON
-if test -n "$PYTHON"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PYTHON" >&5
-$as_echo "$PYTHON" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
-  test -n "$PYTHON" && break
-done
-test -n "$PYTHON" || PYTHON="not-found"
-
-if test "$PYTHON" = not-found; then
-    ASDLGEN="@echo python: $PYTHON! cannot run \$(srcdir)/Parser/asdl_c.py #"
-else
-    ASDLGEN="$PYTHON"
-fi
-
-
-for ac_prog in python$PACKAGE_VERSION python3 python
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_PYTHON+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test -n "$PYTHON"; then
-  ac_cv_prog_PYTHON="$PYTHON" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
-    ac_cv_prog_PYTHON="$ac_prog"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-fi
-fi
-PYTHON=$ac_cv_prog_PYTHON
-if test -n "$PYTHON"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PYTHON" >&5
-$as_echo "$PYTHON" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
-  test -n "$PYTHON" && break
-done
-test -n "$PYTHON" || PYTHON="not-found"
-
-if test "$PYTHON" = not-found; then
-    OPCODEHGEN="@echo python: $PYTHON! cannot run Tools/scripts/generate_opcode_h.py"
-else
-    OPCODEHGEN="$PYTHON"
-fi
-
-
-
 case $MACHDEP in
 bsdos*|hp*|HP*)
 	# install -d does not work on BSDI or HP-UX
diff -r 829117ae2e55 configure.ac
--- a/configure.ac	Tue Jul 19 16:46:09 2016 -0500
+++ b/configure.ac	Fri Jul 22 11:19:17 2016 +0200
@@ -57,6 +57,14 @@
 # pybuilddir.txt will be created by --generate-posix-vars in the Makefile
 rm -f pybuilddir.txt
 
+AC_CHECK_PROGS(PYTHON_FOR_GEN, python$PACKAGE_VERSION python3 python, not-found)
+if test "$PYTHON_FOR_GEN" = not-found; then
+    PYTHON_FOR_GEN='@echo "Cannot generate $@, python not found !" && \
+    echo "To skip re-generation of $@ run <make touch> or <make -t $@>." && \
+    echo "Otherwise, set python in PATH and run configure or run <make PYTHON_FOR_GEN=python>." && false &&'
+fi
+AC_SUBST(PYTHON_FOR_GEN)
+
 if test "$cross_compiling" = yes; then
     AC_MSG_CHECKING([for python interpreter for cross build])
     if test -z "$PYTHON_FOR_BUILD"; then
@@ -1204,23 +1212,6 @@
 fi
 AC_SUBST(READELF)
 
-AC_SUBST(ASDLGEN)
-AC_CHECK_PROGS(PYTHON, python$PACKAGE_VERSION python3 python, not-found)
-if test "$PYTHON" = not-found; then
-    ASDLGEN="@echo python: $PYTHON! cannot run \$(srcdir)/Parser/asdl_c.py #"
-else
-    ASDLGEN="$PYTHON"
-fi
-
-AC_SUBST(OPCODEHGEN)
-AC_CHECK_PROGS(PYTHON, python$PACKAGE_VERSION python3 python, not-found)
-if test "$PYTHON" = not-found; then
-    OPCODEHGEN="@echo python: $PYTHON! cannot run Tools/scripts/generate_opcode_h.py"
-else
-    OPCODEHGEN="$PYTHON"
-fi
-
-
 
 case $MACHDEP in
 bsdos*|hp*|HP*)