René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"A oneOf/anyOf branch that is an array of an inline enum gets the same type name as its items","articleBody":"When a union branch is an array whose items are an inline enum, the branch's type and the items' enum type get the same name (`...Roles1`). In a request body or a parameter, generation succeeds and the output doesn't compile. In a component schema, generation fails with \"duplicate typename\", and the suggested `x-go-name` doesn't apply, since both names are generated.\n\n\"A string or a list of strings\" (`oneOf: [string, array of string]`) is a common shape; adding an `enum` to the items is enough to trigger this.\n\n## Reproduction\n\n`openapi.yaml`:\n\n```yaml\nopenapi: 3.0.3\ninfo: {title: t, version: \"1\"}\npaths:\n  /items:\n    post:\n      requestBody:\n        content:\n          application/json:\n            schema:\n              type: object\n              properties:\n                roles:\n                  oneOf:\n                    - {type: string}\n                    - {type: array, items: {type: string, enum: [admin, viewer]}}\n      responses:\n        \"204\": {description: ok}\n```\n\n```console\n$ oapi-codegen -generate types -package api -o api.gen.go openapi.yaml\n$ go build ./...\n./api.gen.go:21:6: invalid recursive type: PostItemsJSONBodyRoles1 refers to itself\n./api.gen.go:24:6: PostItemsJSONBodyRoles1 redeclared in this block\n\t./api.gen.go:21:6: other declaration of PostItemsJSONBodyRoles1\n```\n\nNo configuration file; the module requires `github.com/oapi-codegen/runtime` v1.8.0. The generated code:\n\n```go\n// PostItemsJSONBodyRoles1 defines parameters for PostItems.\ntype PostItemsJSONBodyRoles1 = []PostItemsJSONBodyRoles1\n\n// PostItemsJSONBodyRoles1 defines parameters for PostItems.\ntype PostItemsJSONBodyRoles1 string\n```\n\nOn `main` the first one is `type PostItemsJSONBodyRoles1 []PostItemsJSONBodyRoles1` and only the \"redeclared\" error remains.\n\nThe same `roles` property as a query parameter's schema gives `GetItemsParamsRoles1 redeclared`. Under `components.schemas.Item` (referenced from a response) generation fails instead:\n\n```text\nerror generating code: error generating code for type definitions: duplicate typename 'ItemRoles1' detected, can't auto-rename, please use x-go-name to specify your own name for one of them\n```\n\nIt also happens with a single-branch `oneOf`, with `anyOf`, with an enum on the string branch too, and with `resolve-type-name-collisions: true`. It reproduces on v2.4.1 as well. Setting `x-go-type-name` on the items (`items: {type: string, enum: [admin, viewer], x-go-type-name: Role}`) works around it.\n\n## Expected\n\nTwo distinct types, for example `PostItemsJSONBodyRoles1 []PostItemsJSONBodyRoles1Item` and `PostItemsJSONBodyRoles1Item string`, and code that compiles.\n\n## Versions\n\nv2.8.1 and `main` (15f5714, `v2.8.1-0.20261028140811-15f571472ff8`), Go 1.27.3, linux/amd64.\n\n## Likely cause\n\nAn array's items are generated at the array's own path (`generateGoSchema(ctx.at(itemHint), schema.Items, path)`, `pkg/codegen/schema.go:1729` on main), and an inline enum is named from its path (`schema.go:1693`), so the items' enum takes the array's name. A plain array property never gets a type of its own, so this doesn't show there. But `generateUnionElement` (`pkg/codegen/union.go:89`) names the array branch from that same path. #1878 had a similar shape: an array with an `enum` of its own and an enum on its items, both called `ApprovalConfigurationExclude`.\n","author":{"url":"https://github.com/BogdanYarotsky","@type":"Person","name":"BogdanYarotsky"},"datePublished":"2026-10-29T06:29:10Z","url":"https://github.com/oapi-codegen/oapi-codegen/issues/2640"}