Refs #30116 -- Simplified regex match group access with Match.__getitem__().

The method has been available since Python 3.6. The shorter syntax is
also marginally faster.

django/db/backends/sqlite3/introspection.py

@@ -17,7 +17,7 @@ field_size_re = _lazy_re_compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$')
 def get_field_size(name):
     """ Extract the size number from a "varchar(11)" type name """
     m = field_size_re.search(name)
-    return int(m.group(1)) if m else None
+    return int(m[1]) if m else None
 
 
 # This light wrapper "fakes" a dictionary interface, because some SQLite data
@@ -147,7 +147,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             if field_desc.startswith("FOREIGN KEY"):
                 # Find name of the target FK field
                 m = re.match(r'FOREIGN KEY\s*\(([^\)]*)\).*', field_desc, re.I)
-                field_name = m.groups()[0].strip('"')
+                field_name = m[1].strip('"')
             else:
                 field_name = field_desc.split()[0].strip('"')
 
@@ -218,7 +218,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             field_desc = field_desc.strip()
             m = re.match(r'(?:(?:["`\[])(.*)(?:["`\]])|(\w+)).*PRIMARY KEY.*', field_desc)
             if m:
-                return m.group(1) if m.group(1) else m.group(2)
+                return m[1] if m[1] else m[2]
         return None
 
     def _get_foreign_key_constraints(self, cursor, table_name):

django/db/migrations/autodetector.py

@@ -1325,5 +1325,5 @@ class MigrationAutodetector:
         """
         match = re.match(r'^\d+', name)
         if match:
-            return int(match.group())
+            return int(match[0])
         return None

django/db/models/sql/compiler.py

@@ -383,7 +383,7 @@ class SQLCompiler:
             # not taken into account so we strip it. When this entire method
             # is refactored into expressions, then we can check each part as we
             # generate it.
-            without_ordering = self.ordering_parts.search(sql).group(1)
+            without_ordering = self.ordering_parts.search(sql)[1]
             params_hash = make_hashable(params)
             if (without_ordering, params_hash) in seen:
                 continue
@@ -396,7 +396,7 @@ class SQLCompiler:
         if self.query.distinct and not self.query.distinct_fields:
             select_sql = [t[1] for t in select]
             for expr, (sql, params, is_ref) in order_by:
-                without_ordering = self.ordering_parts.search(sql).group(1)
+                without_ordering = self.ordering_parts.search(sql)[1]
                 if not is_ref and (without_ordering, params) not in select_sql:
                     extra_select.append((expr, (without_ordering, params), None))
         return extra_select