[mypyc] Only generate an export table if using separate compilation

When not using separate compilation, the export table is not
used. Also, there's actually no simple and safe way to use it without
separate compilation, since we'd have to first ensure that the
structure of the export table is compatible, as otherwise the order of
fields or the types of the fields could be incompatible and cause
segfaults and other fun stuff.

Author: JukkaL

mypyc/codegen/emitmodule.py

@@ -652,7 +652,8 @@ def generate_c_for_modules(self) -> list[tuple[str, str]]:
                 decls.emit_lines(*declaration.decl)
 
         if self.group_name:
-            self.generate_export_table(ext_declarations, emitter)
+            if self.compiler_options.separate:
+                self.generate_export_table(ext_declarations, emitter)
 
             self.generate_shared_lib_init(emitter)
 
@@ -809,20 +810,21 @@ def generate_shared_lib_init(self, emitter: Emitter) -> None:
             "",
         )
 
-        emitter.emit_lines(
-            'capsule = PyCapsule_New(&exports, "{}.exports", NULL);'.format(
-                shared_lib_name(self.group_name)
-            ),
-            "if (!capsule) {",
-            "goto fail;",
-            "}",
-            'res = PyObject_SetAttrString(module, "exports", capsule);',
-            "Py_DECREF(capsule);",
-            "if (res < 0) {",
-            "goto fail;",
-            "}",
-            "",
-        )
+        if self.compiler_options.separate:
+            emitter.emit_lines(
+                'capsule = PyCapsule_New(&exports, "{}.exports", NULL);'.format(
+                    shared_lib_name(self.group_name)
+                ),
+                "if (!capsule) {",
+                "goto fail;",
+                "}",
+                'res = PyObject_SetAttrString(module, "exports", capsule);',
+                "Py_DECREF(capsule);",
+                "if (res < 0) {",
+                "goto fail;",
+                "}",
+                "",
+            )
 
         for mod in self.modules:
             name = exported_name(mod)