Stage generated files to a temporary name

Generate to a temporary name, so that a failure in the script does not
leave behind an up-to-date incomplete file.  If the script exits
successfully, then rename the file to its proper name.

Author: Kevin Pyle

Makefile

@@ -193,11 +193,16 @@ autogenerated-EXTRA_CFLAGS.txt: autogenerated-config.h
 # autogenerated-casts.h is a byproduct of making autogenerated-casts.c
 autogenerated-casts.h: autogenerated-casts.c
 
+# Generate to a temporary name, so that a failure in the script does not
+# leave behind an up-to-date incomplete file.
 $(PLUGIN_GENERATED_SOURCE_FILES): autogenerated-%.c: $(addprefix $(srcdir),generate-%-c.py $(GENERATOR_DEPS))
-	$(PYTHON) $< > $@
+	$(PYTHON) $< > "$@.part" || { rc=$$?; $(RM) "$@.part"; exit $$rc; }
+	mv -f "$@.part" "$@"
 
-autogenerated-casts.c:  autogenerated-gimple-types.txt autogenerated-tree-types.txt autogenerated-rtl-types.txt $(srcdir)generate-casts-c.py
-	$(PYTHON) $(srcdir)generate-casts-c.py autogenerated-casts.c autogenerated-casts.h
+autogenerated-casts.c: GENERATED_FILES:=autogenerated-casts.c autogenerated-casts.h 
+autogenerated-casts.c: $(srcdir)generate-casts-c.py autogenerated-gimple-types.txt autogenerated-tree-types.txt autogenerated-rtl-types.txt
+	$(PYTHON) $< $(addsuffix .part,$(GENERATED_FILES)) || { rc=$$?; $(RM) $(addsuffix .part,$(GENERATED_FILES)); exit $$rc; }
+	: $(foreach f,$(GENERATED_FILES),&& mv -f "$f.part" "$f")
 
 autogenerated-gimple.c: autogenerated-gimple-types.txt autogenerated-tree-types.txt autogenerated-rtl-types.txt $(srcdir)maketreetypes.py
 autogenerated-tree.c: autogenerated-tree-types.txt $(srcdir)maketreetypes.py