fix: List correct enum options when multiple types with same name are present

The schema cache and OpenAPI output would currently list the first found
enum with the same name instead of the correct type. One other case
where this comes up is when a regular type and an enum type have the
same name. For example in the spec fixtures, we have an enum called
"bit". Every "bit" type, no matter whether it's that enum or the
built-in bit type, will show those enum options in the OpenApi output.

Not adding a test, because OpenAPI is supposed to go away in the future
anyway.

CHANGELOG.md

@@ -16,6 +16,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
  - #3093, Nested empty embeds no longer show empty values and are correctly omitted - @laurenceisla
  - #3644, Make --dump-schema work with in-database pgrst.db_schemas setting - @wolfgangwalther
  - #3644, Show number of timezones in schema cache load report - @wolfgangwalther
+ - #3644, List correct enum options in OpenApi output when multiple types with same name are present - @wolfgangwalther
 
 ### Changed
 

src/PostgREST/SchemaCache.hs

@@ -651,7 +651,7 @@ tablesSqlQuery =
               information_schema._pg_truetypid(a.*, t.*),
               information_schema._pg_truetypmod(a.*, t.*)
           )::integer AS character_maximum_length,
-          COALESCE(bt.typname, t.typname)::name AS udt_name,
+          COALESCE(bt.oid, t.oid) AS base_type,
           a.attnum::integer AS position
       FROM pg_attribute a
           LEFT JOIN pg_description AS d
@@ -688,14 +688,13 @@ tablesSqlQuery =
     FROM columns info
     LEFT OUTER JOIN (
         SELECT
-            n.nspname AS s,
-            t.typname AS n,
+            e.enumtypid,
             array_agg(e.enumlabel ORDER BY e.enumsortorder) AS vals
         FROM pg_type t
         JOIN pg_enum e ON t.oid = e.enumtypid
         JOIN pg_namespace n ON n.oid = t.typnamespace
-        GROUP BY s,n
-    ) AS enum_info ON info.udt_name = enum_info.n
+        GROUP BY enumtypid
+    ) AS enum_info ON info.base_type = enum_info.enumtypid
     GROUP BY info.relid
   ),
   tbl_pk_cols AS (