`cargo rustdoc -- --output-format json` now says a tuple variant is a struct variant

[dsherret]

Note the current type of Variant in rustdoc-json-types:

rust/src/rustdoc-json-types/lib.rs

Lines 271 to 275 in eaf6f46

	pub enum Variant {
	Plain,
	Tuple(Vec<Type>),
	Struct(Vec<Id>),
	}

Code

I tried this code:

pub enum MyEnum {
    Variant(MyStruct),
}

pub struct MyStruct {
}

And ran this:

cargo +nightly rustdoc -- --output-format json -Z unstable-options 

I expected to see this happen (or something along these lines saying it's a tuple variant):

    "0:3": {
      "id": "0:3",
      "crate_id": 0,
      "name": "MyEnum",
      "span": { "filename": "src\\lib.rs", "begin": [1, 0], "end": [3, 1] },
      "visibility": "public",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "enum",
      "inner": {
        "generics": { "params": [], "where_predicates": [] },
        "variants_stripped": false,
        "variants": ["0:4"],
        "impls": [
          "F0:0",
          "F0:1",
          "F0:2",
          "F0:4",
          "F0:5",
          "F0:6",
          "F0:7",
          "F0:8",
          "F0:9",
          "F0:10",
          "F0:11",
          "F0:12"
        ]
      }
    },
    "0:4": {
      "id": "0:4",
      "crate_id": 0,
      "name": "Variant",
      "span": { "filename": "src\\lib.rs", "begin": [2, 4], "end": [2, 21] },
      "visibility": "default",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "variant",
      "inner": {
        "variant_kind": "tuple",
        "variant_inner": [
          {
            "kind": "resolved_path",
            "inner": {
              "name": "MyStruct",
              "id": "0:7",
              "args": { "angle_bracketed": { "args": [], "bindings": [] } },
              "param_names": []
            }
          }
        ]
      }
    }

Instead, this happened:

    "0:3": {
      "id": "0:3",
      "crate_id": 0,
      "name": "MyEnum",
      "span": { "filename": "src\\lib.rs", "begin": [1, 0], "end": [3, 1] },
      "visibility": "public",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "enum",
      "inner": {
        "generics": { "params": [], "where_predicates": [] },
        "variants_stripped": false,
        "variants": ["0:4"],
        "impls": [
          "a:2:2881-0:3",
          "a:2:2893-0:3",
          "a:2:2922-0:3",
          "a:1:5759-0:3",
          "a:1:5760-0:3",
          "b:2:2814-0:3",
          "b:2:2810-0:3",
          "b:2:2825-0:3",
          "b:2:2820-0:3",
          "b:2:2486-0:3",
          "b:2:2489-0:3",
          "b:2:3546-0:3"
        ]
      }
    },
    "0:4": {
      "id": "0:4",
      "crate_id": 0,
      "name": "Variant",
      "span": { "filename": "src\\lib.rs", "begin": [2, 4], "end": [2, 21] },
      "visibility": "default",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "variant",
      "inner": { "variant_kind": "struct", "variant_inner": ["0:6"] }
    },

Another Example

Here's a more complicated example:

pub enum MyEnum {
    Variant(MyStruct<String>, MyStruct<String>),
}

pub struct MyStruct<T> {
    pub value: T,
}

Outputs:

    "0:3": {
      "id": "0:3",
      "crate_id": 0,
      "name": "MyEnum",
      "span": { "filename": "src\\lib.rs", "begin": [1, 0], "end": [3, 1] },
      "visibility": "public",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "enum",
      "inner": {
        "generics": { "params": [], "where_predicates": [] },
        "variants_stripped": false,
        "variants": ["0:4"],
        "impls": [
          "a:2:2881-0:3",
          "a:2:2893-0:3",
          "a:2:2922-0:3",
          "a:1:5759-0:3",
          "a:1:5760-0:3",
          "b:2:2814-0:3",
          "b:2:2810-0:3",
          "b:2:2825-0:3",
          "b:2:2820-0:3",
          "b:2:2486-0:3",
          "b:2:2489-0:3",
          "b:2:3546-0:3"
        ]
      }
    },
    "0:4": {
      "id": "0:4",
      "crate_id": 0,
      "name": "Variant",
      "span": { "filename": "src\\lib.rs", "begin": [2, 4], "end": [2, 47] },
      "visibility": "default",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "variant",
      "inner": { "variant_kind": "struct", "variant_inner": ["0:6", "0:7"] }
    },
    "0:6": {
      "id": "0:6",
      "crate_id": 0,
      "name": "0",
      "span": { "filename": "src\\lib.rs", "begin": [2, 12], "end": [2, 28] },
      "visibility": "default",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "struct_field",
      "inner": {
        "kind": "resolved_path",
        "inner": {
          "name": "MyStruct",
          "id": "0:8",
          "args": {
            "angle_bracketed": {
              "args": [
                {
                  "type": {
                    "kind": "resolved_path",
                    "inner": {
                      "name": "String",
                      "id": "5:7431",
                      "args": {
                        "angle_bracketed": { "args": [], "bindings": [] }
                      },
                      "param_names": []
                    }
                  }
                }
              ],
              "bindings": []
            }
          },
          "param_names": []
        }
      }
    },
    "0:7": {
      "id": "0:7",
      "crate_id": 0,
      "name": "1",
      "span": { "filename": "src\\lib.rs", "begin": [2, 30], "end": [2, 46] },
      "visibility": "default",
      "docs": null,
      "links": {},
      "attrs": [],
      "deprecation": null,
      "kind": "struct_field",
      "inner": {
        "kind": "resolved_path",
        "inner": {
          "name": "MyStruct",
          "id": "0:8",
          "args": {
            "angle_bracketed": {
              "args": [
                {
                  "type": {
                    "kind": "resolved_path",
                    "inner": {
                      "name": "String",
                      "id": "5:7431",
                      "args": {
                        "angle_bracketed": { "args": [], "bindings": [] }
                      },
                      "param_names": []
                    }
                  }
                }
              ],
              "bindings": []
            }
          },
          "param_names": []
        }
      }
    }

Version it worked on

It most recently worked on: nightly-2021-06-27 -- I did not do any tests for the specific version it started failing in

Version with regression

rustc +nightly --version --verbose:

rustc 1.56.0-nightly (ad981d58e 2021-08-08)
binary: rustc
commit-hash: ad981d58e1ca16bcf4072577934630deb11c5e14
commit-date: 2021-08-08
host: x86_64-unknown-linux-gnu
release: 1.56.0-nightly
LLVM version: 12.0.1

[camelid]

Regression occurred sometime between nightly-2021-07-28 and nightly-2021-08-08, and #87451 seems likely to be the cause anyway.