fix(codegen/golang): don't omit enums used as arrays (#4058)

Author: andrewmbenton

internal/codegen/golang/gen.go

@@ -383,7 +383,7 @@ func filterUnusedStructs(enums []Enum, structs []Struct, queries []Query) ([]Enu
 			keepTypes[query.Ret.Type()] = struct{}{}
 			if query.Ret.IsStruct() {
 				for _, field := range query.Ret.Struct.Fields {
-					keepTypes[field.Type] = struct{}{}
+					keepTypes[strings.TrimPrefix(field.Type, "[]")] = struct{}{}
 					for _, embedField := range field.EmbedFields {
 						keepTypes[embedField.Type] = struct{}{}
 					}

internal/endtoend/testdata/omit_unused_structs/postgresql/stdlib/go/models.go

@@ -15,3 +15,6 @@ 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;
+
+-- name: query_enum_array_table :many
+SELECT * FROM array_enum_table;

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

@@ -58,4 +58,12 @@ CREATE TYPE query_sqlc_embed_enum AS ENUM (
 CREATE TABLE query_sqlc_embed_table (
     id      INTEGER PRIMARY KEY,
     value   query_sqlc_embed_enum
-)
+);
+
+CREATE TYPE array_enum AS ENUM (
+    'o', 'p'
+);
+CREATE TABLE array_enum_table (
+    id      INTEGER PRIMARY KEY,
+    value   array_enum[]
+);