Swift: reject uppercase acronyms in schema

This was causing hardly debuggable errors because names are transformed
to underscored lowercase names in the dbscheme and back to camelcase
for trap emission classes, which is not a noop in case uppercase
acronyms (like SIL or ABI) are in the name.

This makes the error be surfaced early with a helpful message.

swift/codegen/lib/schema/schema.py

@@ -9,6 +9,7 @@ from enum import Enum, auto
 import functools
 import importlib.util
 from toposort import toposort_flatten
+import inflection
 
 
 class Error(Exception):
@@ -210,8 +211,12 @@ class _PropertyNamer(PropertyModifier):
 def _get_class(cls: type) -> Class:
     if not isinstance(cls, type):
         raise Error(f"Only class definitions allowed in schema, found {cls}")
-    if cls.__name__[0].islower():
-        raise Error(f"Class name must be capitalized, found {cls.__name__}")
+    # we must check that going to dbscheme names and back is preserved
+    # In particular this will not happen if uppercase acronyms are included in the name
+    to_underscore_and_back = inflection.camelize(inflection.underscore(cls.__name__), uppercase_first_letter=True)
+    if cls.__name__ != to_underscore_and_back:
+        raise Error(f"Class name must be upper camel-case, without capitalized acronyms, found {cls.__name__} "
+                    f"instead of {to_underscore_and_back}")
     if len({b._group for b in cls.__bases__ if hasattr(b, "_group")}) > 1:
         raise Error(f"Bases with mixed groups for {cls.__name__}")
     if any(getattr(b, "_null", False) for b in cls.__bases__):

swift/codegen/test/test_schema.py

@@ -669,5 +669,16 @@ def test_null_class_cannot_be_defined_multiple_times():
                 pass
 
 
+def test_uppercase_acronyms_are_rejected():
+    with pytest.raises(schema.Error):
+        @schema.load
+        class data:
+            class Root:
+                pass
+
+            class ROTFLNode(Root):
+                pass
+
+
 if __name__ == '__main__':
     sys.exit(pytest.main([__file__] + sys.argv[1:]))