py: Automatically provide weak links from "foo" to "ufoo" module name.

This commit implements automatic module weak links for all built-in
modules, by searching for "ufoo" in the built-in module list if "foo"
cannot be found.  This means that all modules named "ufoo" are always
available as "foo".  Also, a port can no longer add any other weak links,
which makes strict the definition of a weak link.

It saves some code size (about 100-200 bytes) on ports that previously had
lots of weak links.

Some changes from the previous behaviour:
- It doesn't intern the non-u module names (eg "foo" is not interned),
  which saves code size, but will mean that "import foo" creates a new qstr
  (namely "foo") in RAM (unless the importing module is frozen).
- help('modules') no longer lists non-u module names, only the u-variants;
  this reduces duplication in the help listing.

Weak links are effectively the same as having a set of symbolic links on
the filesystem that is searched last.  So an "import foo" will search
built-in modules first, then all paths in sys.path, then weak links last,
importing "ufoo" if it exists.  Thus a file called "foo.py" somewhere in
sys.path will still have precedence over the weak link of "foo" to "ufoo".

See issues: #1740, #4449, #5229, #5241.

1 files changed, 0 insertions, 15 deletions

diff --git a/ports/javascript/mpconfigport.h b/ports/javascript/mpconfigport.h
index 02d83f402..8ea43d84c 100644
--- a/ports/javascript/mpconfigport.h
+++ b/ports/javascript/mpconfigport.h
@@ -131,21 +131,6 @@ extern const struct _mp_obj_module_t mp_module_utime;
 #define MICROPY_PORT_BUILTIN_MODULES \
     { MP_ROM_QSTR(MP_QSTR_utime), MP_ROM_PTR(&mp_module_utime) }, \
 
-#define MICROPY_PORT_BUILTIN_MODULE_WEAK_LINKS \
-    { MP_ROM_QSTR(MP_QSTR_binascii), MP_ROM_PTR(&mp_module_ubinascii) }, \
-    { MP_ROM_QSTR(MP_QSTR_collections), MP_ROM_PTR(&mp_module_collections) }, \
-    { MP_ROM_QSTR(MP_QSTR_re), MP_ROM_PTR(&mp_module_ure) }, \
-    { MP_ROM_QSTR(MP_QSTR_zlib), MP_ROM_PTR(&mp_module_uzlib) }, \
-    { MP_ROM_QSTR(MP_QSTR_json), MP_ROM_PTR(&mp_module_ujson) }, \
-    { MP_ROM_QSTR(MP_QSTR_heapq), MP_ROM_PTR(&mp_module_uheapq) }, \
-    { MP_ROM_QSTR(MP_QSTR_hashlib), MP_ROM_PTR(&mp_module_uhashlib) }, \
-    { MP_ROM_QSTR(MP_QSTR_io), MP_ROM_PTR(&mp_module_io) }, \
-    { MP_ROM_QSTR(MP_QSTR_random), MP_ROM_PTR(&mp_module_urandom) }, \
-    { MP_ROM_QSTR(MP_QSTR_time), MP_ROM_PTR(&mp_module_utime) }, \
-    { MP_ROM_QSTR(MP_QSTR_select), MP_ROM_PTR(&mp_module_uselect) }, \
-    { MP_ROM_QSTR(MP_QSTR_struct), MP_ROM_PTR(&mp_module_ustruct) }, \
-    { MP_ROM_QSTR(MP_QSTR_errno), MP_ROM_PTR(&mp_module_uerrno) }, \
-
 //#define MICROPY_EVENT_POLL_HOOK {ets_event_poll();}
 #if MICROPY_PY_THREAD
 #define MICROPY_EVENT_POLL_HOOK \