py/makemoduledefs.py: Avoid empty extensible module lists.

An empty array is a C extension supported by clang & GCC but not MSVC.

This also saves a bit of code size if there are no extensible modules.

Fixes issue #18141.

Signed-off-by: Jeff Epler <jepler@unpythonic.net>

1 files changed, 11 insertions, 5 deletions

diff --git a/py/makemoduledefs.py b/py/makemoduledefs.py
index 1488db5c9..c8fdc21f6 100644
--- a/py/makemoduledefs.py
+++ b/py/makemoduledefs.py
@@ -85,19 +85,25 @@ def generate_module_table_header(modules):
             )
         )
 
+    # There should always be at least one module (__main__ in runtime.c)
+    assert mod_defs
+
     print("\n#define MICROPY_REGISTERED_MODULES \\")
 
     for mod_def in sorted(mod_defs):
         print("    {mod_def} \\".format(mod_def=mod_def))
-
     print("// MICROPY_REGISTERED_MODULES")
 
-    print("\n#define MICROPY_REGISTERED_EXTENSIBLE_MODULES \\")
+    # There are not necessarily any extensible modules (e.g., bare-arm or minimal x86)
+    print("\n#define MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES ", len(extensible_mod_defs))
 
-    for mod_def in sorted(extensible_mod_defs):
-        print("    {mod_def} \\".format(mod_def=mod_def))
+    if extensible_mod_defs:
+        print("\n#define MICROPY_REGISTERED_EXTENSIBLE_MODULES \\")
+
+        for mod_def in sorted(extensible_mod_defs):
+            print("    {mod_def} \\".format(mod_def=mod_def))
 
-    print("// MICROPY_REGISTERED_EXTENSIBLE_MODULES")
+        print("// MICROPY_REGISTERED_EXTENSIBLE_MODULES")
 
 
 def generate_module_delegations(delegations):