# HG changeset patch
# Parent  3f921c3b1e8724a4f5e27e3329a2e451a44db2a9
Issue #22625: Makefile options to use native programs when cross compiling

diff -r 3f921c3b1e87 Makefile.pre.in
--- a/Makefile.pre.in	Fri Mar 11 22:53:15 2016 +0100
+++ b/Makefile.pre.in	Sun Mar 13 05:56:25 2016 +0000
@@ -276,6 +276,8 @@
 ##########################################################################
 # Parser
 PGEN=		Parser/pgen$(EXE)
+# Override this with a natively compiled version if cross compiling:
+PGEN_FOR_BUILD=$(PGEN)
 
 PSRCS=		\
 		Parser/acceler.c \
@@ -481,6 +483,9 @@
 all:		build_all
 build_all:	$(BUILDPYTHON) oldsharedmods sharedmods gdbhooks Programs/_testembed python-config
 
+# Build native prerequisites for cross compiling
+native: Parser/pgen Programs/_freeze_importlib
+
 # Compile a binary with profile guided optimization.
 profile-opt:
 	@if [ $(LLVM_PROF_ERR) == yes ]; then \
@@ -710,17 +715,20 @@
 ############################################################################
 # Importlib
 
+# Override this with a natively compiled version if cross compiling:
+FREEZE_IMPORTLIB=Programs/_freeze_importlib
+
 Programs/_freeze_importlib.o: Programs/_freeze_importlib.c Makefile
 
 Programs/_freeze_importlib: Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN)
 	$(LINKCC) $(PY_LDFLAGS) -o $@ Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
 
-Python/importlib_external.h: $(srcdir)/Lib/importlib/_bootstrap_external.py Programs/_freeze_importlib
-	./Programs/_freeze_importlib \
+Python/importlib_external.h: $(srcdir)/Lib/importlib/_bootstrap_external.py $(FREEZE_IMPORTLIB)
+	$(FREEZE_IMPORTLIB) \
 		$(srcdir)/Lib/importlib/_bootstrap_external.py Python/importlib_external.h
 
-Python/importlib.h: $(srcdir)/Lib/importlib/_bootstrap.py Programs/_freeze_importlib
-	./Programs/_freeze_importlib \
+Python/importlib.h: $(srcdir)/Lib/importlib/_bootstrap.py $(FREEZE_IMPORTLIB)
+	$(FREEZE_IMPORTLIB) \
 		$(srcdir)/Lib/importlib/_bootstrap.py Python/importlib.h
 
 
@@ -781,9 +789,9 @@
 
 $(IO_OBJS): $(IO_H)
 
-$(GRAMMAR_H): $(GRAMMAR_INPUT) $(PGEN)
+$(GRAMMAR_H): $(GRAMMAR_INPUT) $(PGEN_FOR_BUILD)
 		@$(MKDIR_P) Include
-		$(PGEN) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
+		$(PGEN_FOR_BUILD) $(GRAMMAR_INPUT) $(GRAMMAR_H) $(GRAMMAR_C)
 $(GRAMMAR_C): $(GRAMMAR_H)
 		touch $(GRAMMAR_C)
 
@@ -1673,7 +1681,7 @@
 Python/thread.o: @THREADHEADERS@
 
 # Declare targets that aren't real files
-.PHONY: all build_all sharedmods oldsharedmods test quicktest
+.PHONY: all build_all native sharedmods oldsharedmods test quicktest
 .PHONY: install altinstall oldsharedinstall bininstall altbininstall
 .PHONY: maninstall libinstall inclinstall libainstall sharedinstall
 .PHONY: frameworkinstall frameworkinstallframework frameworkinstallstructure
diff -r 3f921c3b1e87 README
--- a/README	Fri Mar 11 22:53:15 2016 +0100
+++ b/README	Sun Mar 13 05:56:25 2016 +0000
@@ -75,6 +75,20 @@
 that is optimized and suitable for distribution or production installation.
 
 
+Cross Compiling
+---------------
+
+[Please fill in.] Possibly something like:
+
+mkdir native cross
+(cd native && ../configure && make native)
+cd cross
+../configure --host=<compiler prefix> --build=x86 \
+    ac_cv_file__dev_ptmx=yes ac_cv_file__dev_ptc=no
+make install DESTDIR=stage PGEN_FOR_BUILD=../native/Parser/pgen \
+    FREEZE_IMPORTLIB=../native/Programs/_freeze_importlib
+
+
 What's New
 ----------