Renamed lang_ext -> bindings, README updates.

Makefile

@@ -126,8 +126,8 @@ clean_leave_profile:
 	rm -rf $(TESTS) tests/t.*
 	rm -rf upb/descriptor.pb
 	rm -rf tools/upbc deps
-	rm -rf lang_ext/lua/upb.so
-	rm -rf lang_ext/python/build
+	rm -rf bindings/lua/upb.so
+	rm -rf bindings/python/build
 
 clean: clean_leave_profile
 	rm -rf $(call rwildcard,,*.gcno) $(call rwildcard,,*.gcda)
@@ -464,21 +464,21 @@ else
   LUA_LDFLAGS =
 endif
 
-LUAEXT=lang_ext/lua/upb.so
+LUAEXT=bindings/lua/upb.so
 lua: $(LUAEXT)
-lang_ext/lua/upb.so: lang_ext/lua/upb.c $(LIBUPB_PIC)
-	$(E) CC lang_ext/lua/upb.c
+bindings/lua/upb.so: bindings/lua/upb.c $(LIBUPB_PIC)
+	$(E) CC bindings/lua/upb.c
 	$(Q) $(CC) $(CFLAGS) $(CPPFLAGS) $(LUA_CPPFLAGS) -fpic -shared -o $@ $< upb/libupb_pic.a $(LUA_LDFLAGS)
 
 
 # Python extension #############################################################
 
 PYTHON=python
-PYTHONEXT=lang_ext/python/build/install/lib/python/upb/__init__.so
+PYTHONEXT=bindings/python/build/install/lib/python/upb/__init__.so
 python: $(PYTHONEXT)
-$(PYTHONEXT): $(LIBUPB_PIC) lang_ext/python/upb.c
-	$(E) PYTHON lang_ext/python/upb.c
-	$(Q) cd lang_ext/python && $(PYTHON) setup.py build --debug install --home=build/install
+$(PYTHONEXT): $(LIBUPB_PIC) bindings/python/upb.c
+	$(E) PYTHON bindings/python/upb.c
+	$(Q) cd bindings/python && $(PYTHON) setup.py build --debug install --home=build/install
 
 pythontest: $(PYTHONEXT)
-	cd lang_ext/python && cp test.py build/install/lib/python && valgrind $(PYTHON) ./build/install/lib/python/test.py
+	cd bindings/python && cp test.py build/install/lib/python && valgrind $(PYTHON) ./build/install/lib/python/test.py

README

@@ -1,9 +1,9 @@
 
-upb - a minimalist implementation of protocol buffers.
+upb - a small, low-level protocol buffer library
 
 For API documentation, see the header files.
 
-To build (the core library is ANSI C and has no dependencies):
+To build (the core library is ANSI C99 and has no dependencies):
 $ make
 
 Other useful targets:
@@ -33,10 +33,6 @@ the major things that are broken or not yet implemented yet:
 
 - serialization isn't written yet (only deserialization)
 
-- the language extensions that exist so far (Python and Lua) are totally
-  incomplete/broken.  They are not usable for anything yet.  This will
-  be remedied very soon.
-
 
 CONTACT
 =======

upb/descriptor.c

@@ -304,6 +304,7 @@ static bool upb_fielddef_parsedefault(char *str, upb_value *d, int type) {
   } else if (type == UPB_TYPE(MESSAGE) || type == UPB_TYPE(GROUP)) {
     // We don't expect to get a default value.
     free(str);
+    upb_value_setptr(d, NULL);
     if (str != NULL) success = false;
   } else if (type == UPB_TYPE(BOOL)) {
     if (!str || strcmp(str, "false") == 0)
@@ -356,6 +357,7 @@ static bool upb_fielddef_parsedefault(char *str, upb_value *d, int type) {
         upb_value_setfloat(d, strtof(str, &end));
         if (errno == ERANGE || *end) success = false;
         break;
+      default: abort();
     }
     free(str);
   }
@@ -377,6 +379,7 @@ static void upb_fielddef_endmsg(void *_r, upb_status *status) {
   char *dstr = r->default_string;
   r->default_string = NULL;
   upb_value val;
+  upb_value_setptr(&val, NULL);  // Silence inaccurate compiler warnings.
   if (!upb_fielddef_parsedefault(dstr, &val, f->type)) {
     // We don't worry too much about giving a great error message since the
     // compiler should have ensured this was correct.