Auto merge of #69950 - Centril:rollup-xh0hmvx, r=Centril

Rollup of 10 pull requests

Successful merges:

 - #68899 (Add Display and Error impls for proc_macro::LexError)
 - #69011 (Document unsafe blocks in core::fmt)
 - #69674 (Rename DefKind::Method and TraitItemKind::Method )
 - #69705 (Toolstate: remove redundant beta-week check.)
 - #69722 (Tweak output for invalid negative impl AST errors)
 - #69747 (Rename rustc guide)
 - #69792 (Implement Error for TryReserveError)
 - #69830 (miri: ICE on invalid terminators)
 - #69921 (rustdoc: remove unused import)
 - #69945 (update outdated comment)

Failed merges:

r? @ghost

Author: bors

Diff for: .github/ISSUE_TEMPLATE/tracking_issue.md

@@ -36,11 +36,11 @@ for larger features an implementation could be broken up into multiple PRs.
 
 - [ ] Implement the RFC (cc @rust-lang/XXX -- can anyone write up mentoring
       instructions?)
-- [ ] Adjust documentation ([see instructions on rustc-guide][doc-guide])
-- [ ] Stabilization PR ([see instructions on rustc-guide][stabilization-guide])
+- [ ] Adjust documentation ([see instructions on rustc-dev-guide][doc-guide])
+- [ ] Stabilization PR ([see instructions on rustc-dev-guide][stabilization-guide])
 
-[stabilization-guide]: https://rust-lang.github.io/rustc-guide/stabilization_guide.html#stabilization-pr
-[doc-guide]: https://rust-lang.github.io/rustc-guide/stabilization_guide.html#documentation-prs
+[stabilization-guide]: https://rustc-dev-guide.rust-lang.org/stabilization_guide.html#stabilization-pr
+[doc-guide]: https://rustc-dev-guide.rust-lang.org/stabilization_guide.html#documentation-prs
 
 ### Unresolved Questions
 <!--

Diff for: CONTRIBUTING.md

@@ -19,7 +19,7 @@ hop on the [Rust Discord server][rust-discord] or [Rust Zulip server][rust-zulip
 
 As a reminder, all contributors are expected to follow our [Code of Conduct][coc].
 
-The [rustc-guide] is your friend! It describes how the compiler works and how
+The [rustc-dev-guide] is your friend! It describes how the compiler works and how
 to contribute to it in more detail than this document.
 
 If this is your first time contributing, the [walkthrough] chapter of the guide
@@ -29,8 +29,8 @@ can give you a good example of how a typical contribution would go.
 [rust-discord]: http://discord.gg/rust-lang
 [rust-zulip]: https://rust-lang.zulipchat.com
 [coc]: https://www.rust-lang.org/conduct.html
-[rustc-guide]: https://rust-lang.github.io/rustc-guide/
-[walkthrough]: https://rust-lang.github.io/rustc-guide/walkthrough.html
+[rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/
+[walkthrough]: https://rustc-dev-guide.rust-lang.org/walkthrough.html
 
 ## Feature Requests
 [feature-requests]: #feature-requests
@@ -103,12 +103,12 @@ $ RUST_BACKTRACE=1 rustc ...
 ## The Build System
 
 For info on how to configure and build the compiler, please see [this
-chapter][rustcguidebuild] of the rustc-guide. This chapter contains info for
+chapter][rustcguidebuild] of the rustc-dev-guide. This chapter contains info for
 contributions to the compiler and the standard library. It also lists some
 really useful commands to the build system (`./x.py`), which could save you a
 lot of time.
 
-[rustcguidebuild]: https://rust-lang.github.io/rustc-guide/building/how-to-build-and-run.html
+[rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html
 
 ## Pull Requests
 [pull-requests]: #pull-requests
@@ -336,9 +336,9 @@ to check small fixes. For example, `rustdoc src/doc/reference.md` will render
 reference to `doc/reference.html`. The CSS might be messed up, but you can
 verify that the HTML is right.
 
-Additionally, contributions to the [rustc-guide] are always welcome. Contributions
+Additionally, contributions to the [rustc-dev-guide] are always welcome. Contributions
 can be made directly at [the
-rust-lang/rustc-guide](https://github.com/rust-lang/rustc-guide) repo. The issue
+rust-lang/rustc-dev-guide](https://github.com/rust-lang/rustc-dev-guide) repo. The issue
 tracker in that repo is also a great way to find things that need doing. There
 are issues for beginners and advanced compiler devs alike!
 
@@ -434,7 +434,7 @@ For people new to Rust, and just starting to contribute, or even for
 more seasoned developers, some useful places to look for information
 are:
 
-* The [rustc guide] contains information about how various parts of the compiler work and how to contribute to the compiler
+* The [rustc dev guide] contains information about how various parts of the compiler work and how to contribute to the compiler
 * [Rust Forge][rustforge] contains additional documentation, including write-ups of how to achieve common tasks
 * The [Rust Internals forum][rif], a place to ask questions and
   discuss Rust's internals
@@ -448,13 +448,13 @@ are:
 * **Google!** ([search only in Rust Documentation][gsearchdocs] to find types, traits, etc. quickly)
 * Don't be afraid to ask! The Rust community is friendly and helpful.
 
-[rustc guide]: https://rust-lang.github.io/rustc-guide/about-this-guide.html
+[rustc dev guide]: https://rustc-dev-guide.rust-lang.org/about-this-guide.html
 [gdfrustc]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
 [gsearchdocs]: https://www.google.com/search?q=site:doc.rust-lang.org+your+query+here
 [rif]: http://internals.rust-lang.org
 [rr]: https://doc.rust-lang.org/book/README.html
 [rustforge]: https://forge.rust-lang.org/
 [tlgba]: http://tomlee.co/2014/04/a-more-detailed-tour-of-the-rust-compiler/
 [ro]: http://www.rustaceans.org/
-[rctd]: https://rust-lang.github.io/rustc-guide/tests/intro.html
+[rctd]: https://rustc-dev-guide.rust-lang.org/tests/intro.html
 [cheatsheet]: https://buildbot2.rust-lang.org/homu/

Diff for: README.md

@@ -15,13 +15,13 @@ Read ["Installation"] from [The Book].
 ## Installing from Source
 
 _Note: If you wish to contribute to the compiler, you should read [this
-chapter][rustcguidebuild] of the rustc-guide instead of this section._
+chapter][rustcguidebuild] of the rustc-dev-guide instead of this section._
 
 The Rust build system has a Python script called `x.py` to bootstrap building
 the compiler. More information about it may be found by running `./x.py --help`
-or reading the [rustc guide][rustcguidebuild].
+or reading the [rustc dev guide][rustcguidebuild].
 
-[rustcguidebuild]: https://rust-lang.github.io/rustc-guide/building/how-to-build-and-run.html
+[rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html
 
 ### Building on *nix
 1. Make sure you have installed the dependencies:
@@ -249,13 +249,13 @@ Most real-time collaboration happens in a variety of channels on the
 community, documentation, and all major contribution areas in the Rust ecosystem.
 A good place to ask for help would be the #help channel.
 
-The [rustc guide] might be a good place to start if you want to find out how
+The [rustc dev guide] might be a good place to start if you want to find out how
 various parts of the compiler work.
 
 Also, you may find the [rustdocs for the compiler itself][rustdocs] useful.
 
 [rust-discord]: https://discord.gg/rust-lang
-[rustc guide]: https://rust-lang.github.io/rustc-guide/about-this-guide.html
+[rustc dev guide]: https://rustc-dev-guide.rust-lang.org/about-this-guide.html
 [rustdocs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
 
 ## License

Diff for: src/README.md

@@ -3,6 +3,6 @@ This directory contains the source code of the rust project, including:
 - `libstd`
 - Various submodules for tools, like rustdoc, rls, etc.
 
-For more information on how various parts of the compiler work, see the [rustc guide].
+For more information on how various parts of the compiler work, see the [rustc dev guide].
 
-[rustc guide]: https://rust-lang.github.io/rustc-guide/about-this-guide.html
+[rustc dev guide]: https://rustc-dev-guide.rust-lang.org/about-this-guide.html

Diff for: src/bootstrap/toolstate.rs

@@ -215,13 +215,21 @@ impl Step for ToolStateCheck {
                             tool, old_state, state
                         );
                     } else {
+                        // This warning only appears in the logs, which most
+                        // people won't read. It's mostly here for testing and
+                        // debugging.
                         eprintln!(
                             "warning: Tool `{}` is not test-pass (is `{}`), \
                             this should be fixed before beta is branched.",
                             tool, state
                         );
                     }
                 }
+                // `publish_toolstate.py` is responsible for updating
+                // `latest.json` and creating comments/issues warning people
+                // if there is a regression. That all happens in a separate CI
+                // job on the master branch once the PR has passed all tests
+                // on the `auto` branch.
             }
         }
 
@@ -230,7 +238,7 @@ impl Step for ToolStateCheck {
         }
 
         if builder.config.channel == "nightly" && env::var_os("TOOLSTATE_PUBLISH").is_some() {
-            commit_toolstate_change(&toolstates, in_beta_week);
+            commit_toolstate_change(&toolstates);
         }
     }
 
@@ -325,11 +333,11 @@ fn prepare_toolstate_config(token: &str) {
             Err(_) => false,
         };
         if !success {
-            panic!("git config key={} value={} successful (status: {:?})", key, value, status);
+            panic!("git config key={} value={} failed (status: {:?})", key, value, status);
         }
     }
 
-    // If changing anything here, then please check that src/ci/publish_toolstate.sh is up to date
+    // If changing anything here, then please check that `src/ci/publish_toolstate.sh` is up to date
     // as well.
     git_config("user.email", "[email protected]");
     git_config("user.name", "Rust Toolstate Update");
@@ -373,14 +381,14 @@ fn read_old_toolstate() -> Vec<RepoState> {
 ///
 ///       * See <https://help.github.com/articles/about-commit-email-addresses/>
 ///           if a private email by GitHub is wanted.
-fn commit_toolstate_change(current_toolstate: &ToolstateData, in_beta_week: bool) {
-    let old_toolstate = read_old_toolstate();
-
+fn commit_toolstate_change(current_toolstate: &ToolstateData) {
     let message = format!("({} CI update)", OS.expect("linux/windows only"));
     let mut success = false;
     for _ in 1..=5 {
-        // Update the toolstate results (the new commit-to-toolstate mapping) in the toolstate repo.
-        change_toolstate(&current_toolstate, &old_toolstate, in_beta_week);
+        // Upload the test results (the new commit-to-toolstate mapping) to the toolstate repo.
+        // This does *not* change the "current toolstate"; that only happens post-landing
+        // via `src/ci/docker/publish_toolstate.sh`.
+        publish_test_results(&current_toolstate);
 
         // `git commit` failing means nothing to commit.
         let status = t!(Command::new("git")
@@ -429,31 +437,12 @@ fn commit_toolstate_change(current_toolstate: &ToolstateData, in_beta_week: bool
     }
 }
 
-fn change_toolstate(
-    current_toolstate: &ToolstateData,
-    old_toolstate: &[RepoState],
-    in_beta_week: bool,
-) {
-    let mut regressed = false;
-    for repo_state in old_toolstate {
-        let tool = &repo_state.tool;
-        let state = repo_state.state();
-        let new_state = current_toolstate[tool.as_str()];
-
-        if new_state != state {
-            eprintln!("The state of `{}` has changed from `{}` to `{}`", tool, state, new_state);
-            if new_state < state {
-                if !NIGHTLY_TOOLS.iter().any(|(name, _path)| name == tool) {
-                    regressed = true;
-                }
-            }
-        }
-    }
-
-    if regressed && in_beta_week {
-        std::process::exit(1);
-    }
-
+/// Updates the "history" files with the latest results.
+///
+/// These results will later be promoted to `latest.json` by the
+/// `publish_toolstate.py` script if the PR passes all tests and is merged to
+/// master.
+fn publish_test_results(current_toolstate: &ToolstateData) {
     let commit = t!(std::process::Command::new("git").arg("rev-parse").arg("HEAD").output());
     let commit = t!(String::from_utf8(commit.stdout));
 

Diff for: src/ci/publish_toolstate.sh

@@ -23,7 +23,9 @@ GIT_COMMIT_MSG="$(git log --format=%s -n1 HEAD)"
 cd rust-toolstate
 FAILURE=1
 for RETRY_COUNT in 1 2 3 4 5; do
-    #  The purpose is to publish the new "current" toolstate in the toolstate repo.
+    # The purpose of this is to publish the new "current" toolstate in the toolstate repo.
+    # This happens post-landing, on master.
+    # (Publishing the per-commit test results happens pre-landing in src/bootstrap/toolstate.rs).
     "$(ciCheckoutPath)/src/tools/publish_toolstate.py" "$GIT_COMMIT" \
         "$GIT_COMMIT_MSG" \
         "$MESSAGE_FILE" \

Diff for: src/doc/index.md

@@ -120,7 +120,7 @@ Rust. It's also sometimes called "the 'nomicon."
 
 ## The `rustc` Contribution Guide
 
-[The `rustc` Guide](https://rust-lang.github.io/rustc-guide/) documents how
+[The `rustc` Guide](https://rustc-dev-guide.rust-lang.org/) documents how
 the compiler works and how to contribute to it. This is useful if you want to build
 or modify the Rust compiler from source (e.g. to target something non-standard).
 

Diff for: src/doc/rustc/src/contributing.md

@@ -1,12 +1,12 @@
 # Contributing to rustc
 
 We'd love to have your help improving `rustc`! To that end, we've written [a
-whole book][rustc_guide] on its
+whole book][rustc_dev_guide] on its
 internals, how it works, and how to get started working on it. To learn
 more, you'll want to check that out.
 
 If you would like to contribute to _this_ book, you can find its source in the
 rustc source at [src/doc/rustc][rustc_book].
 
-[rustc_guide]: https://rust-lang.github.io/rustc-guide/
+[rustc_dev_guide]: https://rustc-dev-guide.rust-lang.org/
 [rustc_book]: https://github.com/rust-lang/rust/tree/master/src/doc/rustc

Diff for: src/liballoc/collections/mod.rs

@@ -42,6 +42,7 @@ pub use linked_list::LinkedList;
 pub use vec_deque::VecDeque;
 
 use crate::alloc::{Layout, LayoutErr};
+use core::fmt::Display;
 
 /// The error type for `try_reserve` methods.
 #[derive(Clone, PartialEq, Eq, Debug)]
@@ -77,6 +78,23 @@ impl From<LayoutErr> for TryReserveError {
     }
 }
 
+#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
+impl Display for TryReserveError {
+    fn fmt(
+        &self,
+        fmt: &mut core::fmt::Formatter<'_>,
+    ) -> core::result::Result<(), core::fmt::Error> {
+        fmt.write_str("memory allocation failed")?;
+        let reason = match &self {
+            TryReserveError::CapacityOverflow => {
+                " because the computed capacity exceeded the collection's maximum"
+            }
+            TryReserveError::AllocError { .. } => " because the memory allocator returned a error",
+        };
+        fmt.write_str(reason)
+    }
+}
+
 /// An intermediate trait for specialization of `Extend`.
 #[doc(hidden)]
 trait SpecExtend<I: IntoIterator> {

Diff for: src/libcore/fmt/float.rs

@@ -2,8 +2,6 @@ use crate::fmt::{Debug, Display, Formatter, LowerExp, Result, UpperExp};
 use crate::mem::MaybeUninit;
 use crate::num::flt2dec;
 
-// ignore-tidy-undocumented-unsafe
-
 // Don't inline this so callers don't use the stack space this function
 // requires unless they have to.
 #[inline(never)]
@@ -16,6 +14,7 @@ fn float_to_decimal_common_exact<T>(
 where
     T: flt2dec::DecodableFloat,
 {
+    // SAFETY: Possible undefined behavior, see FIXME(#53491)
     unsafe {
         let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
         let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 4]>::uninit();
@@ -48,6 +47,7 @@ fn float_to_decimal_common_shortest<T>(
 where
     T: flt2dec::DecodableFloat,
 {
+    // SAFETY: Possible undefined behavior, see FIXME(#53491)
     unsafe {
         // enough for f32 and f64
         let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninit();
@@ -103,6 +103,7 @@ fn float_to_exponential_common_exact<T>(
 where
     T: flt2dec::DecodableFloat,
 {
+    // SAFETY: Possible undefined behavior, see FIXME(#53491)
     unsafe {
         let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
         let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 6]>::uninit();
@@ -132,6 +133,7 @@ fn float_to_exponential_common_shortest<T>(
 where
     T: flt2dec::DecodableFloat,
 {
+    // SAFETY: Possible undefined behavior, see FIXME(#53491)
     unsafe {
         // enough for f32 and f64
         let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninit();

Diff for: src/libcore/fmt/mod.rs

@@ -1,7 +1,5 @@
 //! Utilities for formatting and printing strings.
 
-// ignore-tidy-undocumented-unsafe
-
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::cell::{Cell, Ref, RefCell, RefMut, UnsafeCell};
@@ -281,6 +279,14 @@ impl<'a> ArgumentV1<'a> {
     #[doc(hidden)]
     #[unstable(feature = "fmt_internals", reason = "internal to format_args!", issue = "none")]
     pub fn new<'b, T>(x: &'b T, f: fn(&T, &mut Formatter<'_>) -> Result) -> ArgumentV1<'b> {
+        // SAFETY: `mem::transmute(x)` is safe because
+        //     1. `&'b T` keeps the lifetime it originated with `'b`
+        //              (so as to not have an unbounded lifetime)
+        //     2. `&'b T` and `&'b Void` have the same memory layout
+        //              (when `T` is `Sized`, as it is here)
+        // `mem::transmute(f)` is safe since `fn(&T, &mut Formatter<'_>) -> Result`
+        // and `fn(&Void, &mut Formatter<'_>) -> Result` have the same ABI
+        // (as long as `T` is `Sized`)
         unsafe { ArgumentV1 { formatter: mem::transmute(f), value: mem::transmute(x) } }
     }
 
@@ -1399,6 +1405,14 @@ impl<'a> Formatter<'a> {
 
     fn write_formatted_parts(&mut self, formatted: &flt2dec::Formatted<'_>) -> Result {
         fn write_bytes(buf: &mut dyn Write, s: &[u8]) -> Result {
+            // SAFETY: This is used for `flt2dec::Part::Num` and `flt2dec::Part::Copy`.
+            // It's safe to use for `flt2dec::Part::Num` since every char `c` is between
+            // `b'0'` and `b'9'`, which means `s` is valid UTF-8.
+            // It's also probably safe in practice to use for `flt2dec::Part::Copy(buf)`
+            // since `buf` should be plain ASCII, but it's possible for someone to pass
+            // in a bad value for `buf` into `flt2dec::to_shortest_str` since it is a
+            // public function.
+            // FIXME: Determine whether this could result in UB.
             buf.write_str(unsafe { str::from_utf8_unchecked(s) })
         }