[rustdoc-json] ICE/incorect results when reexporting with #[doc(inline)]

[aDotInTheVoid]

Similar to #80664, another ICE due to non identical items.

Cargo.toml

[package]
name = "ice_demo"
version = "0.1.0"
edition="2018"
[dependencies]
foo = { path = "./foo" }

src/lib.rs

#[doc(inline)]
pub use foo::Foo;

pub mod bar {
    pub use foo::Foo;
}

foo/src/lib.rs

pub struct Foo;

Run cargo +nightly rustdoc -- -w json, and it panics here

  left: `Item { id: Id("16:3"), crate_id: 16, name: Some("Foo"), source: Some(Span { filename: "/private/tmp/ice_demo/foo/src/lib.rs", begin: (1, 0), end: (1, 15) }), visibility: Public, docs: None, links: {}, attrs: [], deprecation: None, inner: Struct(Struct { struct_type: Unit, generics: Generics { params: [], where_predicates: [] }, fields_stripped: false, fields: [], impls: [] }) }`,
 right: `Item { id: Id("16:3"), crate_id: 16, name: Some("Foo"), source: Some(Span { filename: "/private/tmp/ice_demo/foo/src/lib.rs", begin: (1, 0), end: (1, 15) }), visibility: Public, docs: None, links: {}, attrs: ["#[doc(inline)]"], deprecation: None, inner: Struct(Struct { struct_type: Unit, generics: Generics { params: [], where_predicates: [] }, fields_stripped: false, fields: [], impls: [] }) }`', src/librustdoc/json/mod.rs:175:17

The difference is one has attrs: [] and the other has attrs: ["#[doc(inline)]"].

This occors as foo::Foo is used twice, once with and once without #[doc(inline)]

Non ICE versions

Import from local

When foo is a internal module and not a crate, this works

mod foo {
    pub struct Foo;
}

#[doc(inline)]
pub use foo::Foo;

pub mod bar {
    pub use crate::foo::Foo;
}

JSON output (redacted for clarity)

{
  "index": {
    "0:0": {
      "attrs": ["#![feature(no_core)]", "#![no_core]"],
      "inner": {"is_crate": true, "items": ["0:5", "0:2"]},
      "kind": "module",
      "name": "ice_demo"
    },
    "0:2": {
      "attrs": [],
      "kind": "struct",
      "name": "Foo"
    },
    "0:5": {
      "attrs": [],
      "inner": {"is_crate": false, "items": ["0:2"]},
      "kind": "module",
      "name": "bar"
    }
  },
  "paths": {
    "0:0": {"crate_id": 0, "kind": "module", "path": ["ice_demo"]},
    "0:2": {"crate_id": 0, "kind": "struct", "path": ["ice_demo", "bar", "Foo"]},
    "0:5": {"crate_id": 0, "kind": "module", "path": ["ice_demo", "bar"]}
  },
  "root": "0:0"
}

Here we drop the #[doc(inline)], which is probably wrong.

This is actualy correct,

Import only once

#[doc(inline)]
pub use foo::Foo;

JSON output

{
  "crate_version": "0.1.0",
  "external_crates": {"1": {"html_root_url": null, "name": "foo"}},
  "format_version": 4,
  "includes_private": false,
  "index": {
    "0:0": {
      "attrs": ["#![no_core]", "#![feature(no_core)]"],
      "inner": {"is_crate": true, "items": ["1:1"]},
      "kind": "module",
      "name": "ice_demo"
    },
    "0:1": {
      "attrs": ["#[doc(inline)]"],
      "inner": {"glob": false, "id": "1:1", "name": "Foo", "span": "foo::Foo"},
      "kind": "import"
    },
    "1:1": {
      "attrs": ["#[doc(inline)]"],   
      "kind": "struct",
      "links": {},
      "name": "Foo"
    }
  },
  "paths": {
    "0:0": {"crate_id": 0, "kind": "module", "path": ["ice_demo"]},
    "1:0": {"crate_id": 1, "kind": "module", "path": ["foo"]},
    "1:1": {"crate_id": 1, "kind": "struct", "path": ["foo", "Foo"]}
  },
  "root": "0:0"
}

This is also wrong, as id 0:1 is not referenced anywhere, and 1:1 is given #[doc(inline)], even though it should have it.

cc @CraftSpider @P1n3appl3

@rustbot modify labels: +C-bug +A-rustdoc-json +T-rustdoc +A-attributes

[aDotInTheVoid]

The import only once case also has the unreference item without #[doc(inline)]

And the reason for the ICE in the first report is attrs: ["#[doc(inline)]"] is being applyed to 1:1, which conflicts when it is used without being inlined.

The Unreferenced 0:1 is a entirely seperate issue (it appears)