This is useful for changing the *default* for whether doctests are
merged or not. Currently, that default is solely controlled by
`edition = 2024`, which adds a high switching cost to get doctest
merging. This flag allows opt-ing in even on earlier additions.

Unlike the `edition = 2024` default, `--merge-doctests=yes` gives a hard
error if merging fails instead of falling back to running standalone
tests. The user has explicitly said they want merging, so we shouldn't
silently do something else.

`--merge-doctests=auto` is equivalent to the current 2024 edition
behavior, but available on earlier editions.

This allows viewing failed merged doctests.

…ign implementors

… to show/hide implementors

…xternal macro

```
error[E0308]: mismatched types
  --> $DIR/macro-span-caller-replacement.rs:5:17
   |
LL |             s = format!("{arg}");
   |                 ^^^^^^^^^^^^^^^^ expected `&str`, found `String`
...
LL |     macro_with_format!();
   |     -------------------- in this macro invocation
   |
   = note: this error originates in the macro `format` which comes from the expansion of the macro `macro_with_format` (in Nightly builds, run with -Z macro-backtrace for more info)
```

… from desugaring

…=yotamofek

Put negative implementors first and apply same ordering logic to foreign implementors

Fixes rust-lang#51129.

This PR changeda surprisingly small amount of things to put negative trait impls before the others: basically just adding a new information in the generated JS file for foreign implementors and a "negative marker" DOM element to know where to insert negative impls.

I also used this occasion to make the foreign implementors sort the same as the local ones by using `compare_names`.

You can test it [here](https://rustdoc.crud.net/imperio/neg-implementors/core/marker/trait.Sync.html#implementors).

r? ```@notriddle```

…aumeGomez

remove duplicated columns from `rustc_error_code::error_codes!`

Possible because of rust-lang#146308 ~~, but currently still blocked on the next stage0 bump~~.

…nkov

Point at span within local macros even when error happens in nested external macro

Address issue noticed at https://users.rust-lang.org/t/error-message-does-not-specify-where-in-macro/135157/1. On errors occurring within a macro expansion, point at the innermost local macro expansion point.

```
error[E0308]: mismatched types
  --> $DIR/macro-span-caller-replacement.rs:5:17
   |
LL |             s = format!("{arg}");
   |                 ^^^^^^^^^^^^^^^^ expected `&str`, found `String`
...
LL |     macro_with_format!();
   |     -------------------- in this macro invocation
   |
   = note: this error originates in the macro `format` which comes from the expansion of the macro `macro_with_format` (in Nightly builds, run with -Z macro-backtrace for more info)
```

…iddle

rustdoc: Add unstable `--merge-doctests=yes/no/auto` flag

This is useful for changing the *default* for whether doctests are merged or not. Currently, that default is solely controlled by `edition = 2024`, which adds a high switching cost to get doctest merging. This flag allows opting in even on earlier editions.

Unlike the `edition = 2024` default, `--merge-doctests=yes` gives a hard error if merging fails instead of falling back to running standalone tests. The user has explicitly said they want merging, so we shouldn't silently do something else.

`--merge-doctests=auto` is equivalent to the current 2024 edition behavior, but available on earlier editions.

Helps with rust-lang#141240. ``@epage`` said in that issue he would like a per-doctest opt-in, and that seems useful to me in addition to this flag, but I think it's a separate use case from changing the default.

…eLapkin

Rename some issue-* tests

Also fixes one incorrect issue number: rust-lang#100168 (comment)

Use ubuntu:24.04 for the `x86_64-gnu-miri` job

Ralf asked for this in https://rust-lang.zulipchat.com/#narrow/channel/242791-t-infra/topic/Adding.20a.20C.2B.2B.20dependency.20to.20Miri.3F/with/560654845.

…yotamofek

Remove "tidy" tool for `tests/rustdoc` testsuite

As discussed in the [last rustdoc meeting](https://rust-lang.zulipchat.com/#narrow/channel/393423-t-rustdoc.2Fmeetings/topic/2025-12-08/near/562554410), it seems like the current `tidy` tool is not used much for the `rustdoc` testsuite by the rustdoc contributors as it doesn't fit nicely our needs.

Until we find something better, we decided to remove it.

r? ```@yotamofek```

Do not suggest moving expression out of for loop when hitting `break` from desugaring

Fix rust-lang#149861.

only resolve main in bin crates

Fixes rust-lang#149412