fix(codegen/go): Prevent filtering of embedded struct fields (#2868)

Resolves #2860

internal/codegen/golang/gen.go

@@ -345,6 +345,9 @@ func filterUnusedStructs(enums []Enum, structs []Struct, queries []Query) ([]Enu
 			if query.Ret.IsStruct() {
 				for _, field := range query.Ret.Struct.Fields {
 					keepTypes[field.Type] = struct{}{}
+					for _, embedField := range field.EmbedFields {
+						keepTypes[embedField.Type] = struct{}{}
+					}
 				}
 			}
 		}

internal/endtoend/testdata/omit_unused_structs/postgresql/stdlib/query.sql

@@ -11,4 +11,7 @@ SELECT id FROM query_param_struct_enum_table WHERE id = $1 AND value = $2;
 SELECT value FROM query_return_enum_table WHERE id = $1;
 
 -- name: query_return_struct_enum_table :one
-SELECT value, another FROM query_return_struct_enum_table WHERE id = $1;
+SELECT value, another FROM query_return_struct_enum_table WHERE id = $1;
+
+-- name: query_sqlc_embed_table :one
+SELECT sqlc.embed(query_sqlc_embed_table) FROM query_sqlc_embed_table WHERE id = $1;

internal/endtoend/testdata/omit_unused_structs/postgresql/stdlib/schema.sql

@@ -50,4 +50,12 @@ CREATE TABLE query_return_struct_enum_table (
     id      INTEGER PRIMARY KEY,
     value   query_return_struct_enum_table_enum,
     another INTEGER
-);
+);
+
+CREATE TYPE query_sqlc_embed_enum AS ENUM (
+    'm', 'n'
+);
+CREATE TABLE query_sqlc_embed_table (
+    id      INTEGER PRIMARY KEY,
+    value   query_sqlc_embed_enum
+)