[rustdoc] Give more information into extracted doctest information

[GuillaumeGomez]

Follow-up of #134531.

This update fragment the doctest code into its sub-parts to give more control to the end users on how they want to use it.

The new JSON looks like this:

{
  "format_version":2,
  "doctests":[
    {
      "file":"$DIR/extract-doctests-result.rs",
      "line":8,
      "doctest_attributes":{
        "original":"",
        "should_panic":false,
        "no_run":false,
        "ignore":"None",
        "rust":true,
        "test_harness":false,
        "compile_fail":false,
        "standalone_crate":false,
        "error_codes":[],
        "edition":null,
        "added_css_classes":[],
        "unknown":[]
      },
      "original_code":"let x = 12;\nOk(())",
      "doctest_code":{
        "crate_level":"#![allow(unused)]\n",
        "code":"let x = 12;\nOk(())",
        "wrapper":{
          "before":"fn main() { fn _inner() -> core::result::Result<(), impl core::fmt::Debug> {\n",
          "after":"\n} _inner().unwrap() }",
          "returns_result":true
        }
      },
      "name":"$DIR/extract-doctests-result.rs - (line 8)"
    }
  ]
}

for this doctest:

let x = 12;
Ok(())

With this, I think it matches what you need @ojeda? If so, once merged I'll update the patch I sent to RfL.

r? @aDotInTheVoid

[GuillaumeGomez]

Fixed fmt.

[lolbinarycat]

Core logic looks correct (mostly just exposing existing variables), just have a few nits about naming to hopefully increase readability.

[GuillaumeGomez]

Updated.

[lolbinarycat]

Looks pretty good, I've just got a few more notes about naming, most of which are extrapolations of previous suggested changes.

[aDotInTheVoid]

This also needs changes to the docs for this feature, which are in the rustdoc book.

[GuillaumeGomez]

Applied suggestions!

[lolbinarycat]

I don't think we should be putting the test stdout directly into the docs, at least not unmodified

[lolbinarycat]

I think we should make it clear that the filename here is the filename of the file that contains the doctest. Since we're using the name src/lib.rs above, shouldn't we use the same name here?

also, aren't the $DIR placeholders are added by compiletest, not rustdoc?

[lolbinarycat]

I don't think copy-pasting the JSON from extract-doctests-results.stdout is 100% correct here, since things like line numbers won't be the same.

[GuillaumeGomez]

I fixed the book example.

[rustbot]

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[oli-obk]

cool, this seems really useful!

[GuillaumeGomez]

For now I only know rust-for-linux as potential users, we'll see if more users will appear in the future.