The test checks that we reuse the CGU of a crate when the implementation
details of an `extern crate` have changed.

Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

linkchecker is no longer run on the compiler docs so they can be removed from the whitelist.

- remove syntax::{help!, span_help!, span_note!}
- remove unused syntax::{struct_span_fatal, struct_span_err_or_warn!, span_err_or_warn!}
- lintify check_for_bindings_named_same_as_variants + conflicting_repr_hints
- inline syntax::{struct_span_warn!, diagnostic_used!}
- stringify_error_code! -> error_code! & use it more.
- find_plugin_registrar: de-fatalize an error
- de-fatalize metadata errors
- move type_error_struct! to rustc_typeck
- struct_span_err! -> rustc_errors

Suggest calling method when first argument is `self`

Closes: rust-lang#66782

I've explored different approaches for this MR but I think the most straightforward is the best one.

I've tried to find out if the methods for given type exist (to maybe have a better suggestion), but we don't collect them anywhere and collecting them is quite problematic. Moreover, collecting all the methods would require rewriting big part of the code and also could potentially include performance degradation, which I don't think is necessary for this simple case.

…akis

no longer promote non-pattern const functions

This is trying to pack-pedal a bit on promotion feature creep, as proposed by @eddyb [here](rust-lang/const-eval#19 (comment)): possibly, a sane subset of `const fn` that we could promote are those that are just constructors -- the same subset that we might want to allow in pattern position at some point.

So, this removes the `rustc_promotable` attribute from the three functions they identified that do not fit this pattern. The first step is to run crater to see if there is code in the wild that relies on this being promotable.

r? @oli-obk

…chenkov

More reductions in error handling diversity

In this follow up to rust-lang#67744, we:

- Remove all fatal / error / warning macros in `syntax` except for `struct_span_err`, which is moved to `rustc_errors`.

- Lintify some hard-coded warnings which used warning macros.

- Defatalize some errors.

In general, the goal here is to make it painful to use fatal or unstructured errors and so we hopefully won't see many of these creep in.

…sakis

Add a test for rust-lang#37333

The test checks that we reuse the CGU of a crate when the implementation
details of an `extern crate` have changed.

Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

…komatsakis

Cleanup linkchecker whitelist

linkchecker is no longer run on the compiler docs so they can be removed from the whitelist.

…r=Manishearth

Implement uncommon_codepoints lint.

Part of rust-lang#55467 .  The checks of `$crate` and `{{root}}` are very unfortunate. But i'm not sure where they belongs to.

tweak wording of mismatched delimiter errors

This PR improves the wording of the "incorrect delimiter" error messages. Here's a quick rationale:

- *"un-closed" -> "unclosed"*: "unclosed" is valid English, so there's no need to hyphenate the prefix. This should be pretty uncontroversial, I think.
- *"close delimiter" -> "closing delimiter"*: In my anecdotal experience, I've always heard "closing delimiter" or "closing parenthesis". In addition, the codebase already uses this terminology in comments and function names more than "close delimiter", which could indicate that it's more intuitive.
- "incorrect delimiter" -> "mismatched delimiter": "Incorrect delimiter" is vague; why is it incorrect? "mismatched" clearly indicates why the delimiter is causing the error.

r? @estebank

…i-obk

Also remove const-hack for abs

Closes rust-lang#67842.

r? @oli-obk