Auto merge of #77224 - RalfJung:rollup-hdvb96c, r=RalfJung

Rollup of 12 pull requests

Successful merges:

 - #75454 (Explicitly document the size guarantees that Option makes.)
 - #76631 (Add `x.py setup`)
 - #77076 (Add missing code examples on slice iter types)
 - #77093 (merge `need_type_info_err(_const)`)
 - #77122 (Add `#![feature(const_fn_floating_point_arithmetic)]`)
 - #77127 (Update mdBook)
 - #77161 (Remove TrustedLen requirement from BuilderMethods::switch)
 - #77166 (update Miri)
 - #77181 (Add doc alias for pointer primitive)
 - #77204 (Remove stray word from `ClosureKind::extends` docs)
 - #77207 (Rename `whence` to `span`)
 - #77211 (Remove unused #[allow(...)] statements from compiler/)

Failed merges:

 - #77170 (Remove `#[rustc_allow_const_fn_ptr]` and add `#![feature(const_fn_fn_ptr_basics)]`)

r? `@ghost`

33 files changed, 351 insertions, 164 deletions

diff --git a/src/bootstrap/CHANGELOG.md b/src/bootstrap/CHANGELOG.md
index 1510f4d59fa..dfb39c54c17 100644
--- a/src/bootstrap/CHANGELOG.md
+++ b/src/bootstrap/CHANGELOG.md
@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Non-breaking changes since the last major version]
 
+- Add `x.py setup` [#76631](https://github.com/rust-lang/rust/pull/76631)
 - Add a changelog for x.py [#76626](https://github.com/rust-lang/rust/pull/76626)
 - Optionally, download LLVM from CI on Linux and NixOS
   + [#76439](https://github.com/rust-lang/rust/pull/76349)
diff --git a/src/bootstrap/bin/main.rs b/src/bootstrap/bin/main.rs
index 6af13fc83d0..637083e08d5 100644
--- a/src/bootstrap/bin/main.rs
+++ b/src/bootstrap/bin/main.rs
@@ -7,21 +7,34 @@
 
 use std::env;
 
-use bootstrap::{Build, Config};
+use bootstrap::{Build, Config, Subcommand};
 
 fn main() {
     let args = env::args().skip(1).collect::<Vec<_>>();
     let config = Config::parse(&args);
 
     let changelog_suggestion = check_version(&config);
-    if let Some(suggestion) = &changelog_suggestion {
+
+    // NOTE: Since `./configure` generates a `config.toml`, distro maintainers will see the
+    // changelog warning, not the `x.py setup` message.
+    let suggest_setup = !config.config.exists() && !matches!(config.cmd, Subcommand::Setup { .. });
+    if suggest_setup {
+        println!("warning: you have not made a `config.toml`");
+        println!("help: consider running `x.py setup` or copying `config.toml.example`");
+    } else if let Some(suggestion) = &changelog_suggestion {
         println!("{}", suggestion);
     }
 
     Build::new(config).build();
 
-    if let Some(suggestion) = changelog_suggestion {
+    if suggest_setup {
+        println!("warning: you have not made a `config.toml`");
+        println!("help: consider running `x.py setup` or copying `config.toml.example`");
+    } else if let Some(suggestion) = &changelog_suggestion {
         println!("{}", suggestion);
+    }
+
+    if suggest_setup || changelog_suggestion.is_some() {
         println!("note: this message was printed twice to make it more likely to be seen");
     }
 }
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index d2537d65e67..4aaaeb8a93b 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -549,7 +549,9 @@ impl<'a> Builder<'a> {
             Subcommand::Dist { ref paths } => (Kind::Dist, &paths[..]),
             Subcommand::Install { ref paths } => (Kind::Install, &paths[..]),
             Subcommand::Run { ref paths } => (Kind::Run, &paths[..]),
-            Subcommand::Format { .. } | Subcommand::Clean { .. } => panic!(),
+            Subcommand::Format { .. } | Subcommand::Clean { .. } | Subcommand::Setup { .. } => {
+                panic!()
+            }
         };
 
         Self::new_internal(build, kind, paths.to_owned())
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 53fef7a838d..b14746dabb9 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -73,6 +73,8 @@ pub struct Config {
     pub keep_stage: Vec<u32>,
     pub keep_stage_std: Vec<u32>,
     pub src: PathBuf,
+    // defaults to `config.toml`
+    pub config: PathBuf,
     pub jobs: Option<u32>,
     pub cmd: Subcommand,
     pub incremental: bool,
@@ -513,6 +515,7 @@ impl Config {
         config.rust_codegen_backends = vec![INTERNER.intern_str("llvm")];
         config.deny_warnings = true;
         config.missing_tools = false;
+        config.config = PathBuf::from("config.toml");
 
         // set by bootstrap.py
         config.build = TargetSelection::from_user(&env!("BUILD_TRIPLE"));
@@ -558,7 +561,7 @@ impl Config {
         let get_toml = |file: PathBuf| {
             use std::process;
 
-            let contents = t!(fs::read_to_string(&file), "configuration file did not exist");
+            let contents = t!(fs::read_to_string(&file), "`include` config not found");
             match toml::from_str(&contents) {
                 Ok(table) => table,
                 Err(err) => {
@@ -644,6 +647,7 @@ impl Config {
             | Subcommand::Clippy { .. }
             | Subcommand::Fix { .. }
             | Subcommand::Run { .. }
+            | Subcommand::Setup { .. }
             | Subcommand::Format { .. } => flags.stage.unwrap_or(0),
         };
 
@@ -668,6 +672,7 @@ impl Config {
                 | Subcommand::Clippy { .. }
                 | Subcommand::Fix { .. }
                 | Subcommand::Run { .. }
+                | Subcommand::Setup { .. }
                 | Subcommand::Format { .. } => {}
             }
         }
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index dad31fc77be..a12fc50afad 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -7,6 +7,7 @@ use std::env;
 use std::path::PathBuf;
 use std::process;
 
+use build_helper::t;
 use getopts::Options;
 
 use crate::builder::Builder;
@@ -89,6 +90,9 @@ pub enum Subcommand {
     Run {
         paths: Vec<PathBuf>,
     },
+    Setup {
+        path: String,
+    },
 }
 
 impl Default for Subcommand {
@@ -199,6 +203,7 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`",
                 || (s == "install")
                 || (s == "run")
                 || (s == "r")
+                || (s == "setup")
         });
         let subcommand = match subcommand {
             Some(s) => s,
@@ -453,10 +458,21 @@ Arguments:
     At least a tool needs to be called.",
                 );
             }
+            "setup" => {
+                subcommand_help.push_str(
+                    "\n
+Arguments:
+    This subcommand accepts a 'profile' to use for builds. For example:
+
+        ./x.py setup library
+
+    The profile is optional and you will be prompted interactively if it is not given.",
+                );
+            }
             _ => {}
         };
         // Get any optional paths which occur after the subcommand
-        let paths = matches.free[1..].iter().map(|p| p.into()).collect::<Vec<PathBuf>>();
+        let mut paths = matches.free[1..].iter().map(|p| p.into()).collect::<Vec<PathBuf>>();
 
         let cfg_file = env::var_os("BOOTSTRAP_CONFIG").map(PathBuf::from);
         let verbose = matches.opt_present("verbose");
@@ -508,6 +524,20 @@ Arguments:
                 }
                 Subcommand::Run { paths }
             }
+            "setup" => {
+                let path = if paths.len() > 1 {
+                    println!("\nat most one profile can be passed to setup\n");
+                    usage(1, &opts, verbose, &subcommand_help)
+                } else if let Some(path) = paths.pop() {
+                    t!(path.into_os_string().into_string().map_err(|path| format!(
+                        "{} is not a valid UTF8 string",
+                        path.to_string_lossy()
+                    )))
+                } else {
+                    t!(crate::setup::interactive_path())
+                };
+                Subcommand::Setup { path }
+            }
             _ => {
                 usage(1, &opts, verbose, &subcommand_help);
             }
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 3f7aeae0ed4..4cc72f5f39c 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -141,6 +141,7 @@ mod metadata;
 mod native;
 mod run;
 mod sanity;
+mod setup;
 mod test;
 mod tool;
 mod toolstate;
@@ -165,7 +166,7 @@ mod job {
 
 use crate::cache::{Interned, INTERNER};
 pub use crate::config::Config;
-use crate::flags::Subcommand;
+pub use crate::flags::Subcommand;
 
 const LLVM_TOOLS: &[&str] = &[
     "llvm-nm", // used to inspect binaries; it shows symbol names, their sizes and visibility
@@ -470,6 +471,10 @@ impl Build {
             return clean::clean(self, all);
         }
 
+        if let Subcommand::Setup { path: include_name } = &self.config.cmd {
+            return setup::setup(&self.config.src, include_name);
+        }
+
         {
             let builder = builder::Builder::new(&self);
             if let Some(path) = builder.paths.get(0) {
diff --git a/src/bootstrap/run.rs b/src/bootstrap/run.rs
index 90053471427..ba593cadbad 100644
--- a/src/bootstrap/run.rs
+++ b/src/bootstrap/run.rs
@@ -10,7 +10,7 @@ impl Step for ExpandYamlAnchors {
 
     /// Runs the `expand-yaml_anchors` tool.
     ///
-    /// This tool in `src/tools` read the CI configuration files written in YAML and expands the
+    /// This tool in `src/tools` reads the CI configuration files written in YAML and expands the
     /// anchors in them, since GitHub Actions doesn't support them.
     fn run(self, builder: &Builder<'_>) {
         builder.info("Expanding YAML anchors in the GitHub Actions configuration");
diff --git a/src/bootstrap/setup.rs b/src/bootstrap/setup.rs
new file mode 100644
index 00000000000..9d3a889aa00
--- /dev/null
+++ b/src/bootstrap/setup.rs
@@ -0,0 +1,88 @@
+use crate::t;
+use std::path::{Path, PathBuf};
+use std::{
+    env, fs,
+    io::{self, Write},
+};
+
+pub fn setup(src_path: &Path, include_name: &str) {
+    let cfg_file = env::var_os("BOOTSTRAP_CONFIG").map(PathBuf::from);
+
+    if cfg_file.as_ref().map_or(false, |f| f.exists()) {
+        let file = cfg_file.unwrap();
+        println!(
+            "error: you asked `x.py` to setup a new config file, but one already exists at `{}`",
+            file.display()
+        );
+        println!(
+            "help: try adding `profile = \"{}\"` at the top of {}",
+            include_name,
+            file.display()
+        );
+        println!(
+            "note: this will use the configuration in {}/src/bootstrap/defaults/config.toml.{}",
+            src_path.display(),
+            include_name
+        );
+        std::process::exit(1);
+    }
+
+    let path = cfg_file.unwrap_or_else(|| src_path.join("config.toml"));
+    let settings = format!(
+        "# Includes one of the default files in src/bootstrap/defaults\n\
+    profile = \"{}\"\n",
+        include_name
+    );
+    t!(fs::write(path, settings));
+
+    let include_path =
+        format!("{}/src/bootstrap/defaults/config.toml.{}", src_path.display(), include_name);
+    println!("`x.py` will now use the configuration at {}", include_path);
+
+    let suggestions = match include_name {
+        "codegen" | "compiler" => &["check", "build", "test"][..],
+        "library" => &["check", "build", "test library/std", "doc"],
+        "user" => &["dist", "build"],
+        _ => return,
+    };
+
+    println!("To get started, try one of the following commands:");
+    for cmd in suggestions {
+        println!("- `x.py {}`", cmd);
+    }
+
+    if include_name != "user" {
+        println!(
+            "For more suggestions, see https://rustc-dev-guide.rust-lang.org/building/suggested.html"
+        );
+    }
+}
+
+// Used to get the path for `Subcommand::Setup`
+pub fn interactive_path() -> io::Result<String> {
+    let mut input = String::new();
+    println!(
+        "Welcome to the Rust project! What do you want to do with x.py?
+a) Contribute to the standard library
+b) Contribute to the compiler
+c) Contribute to the compiler, and also modify LLVM or codegen
+d) Install Rust from source"
+    );
+    let template = loop {
+        print!("Please choose one (a/b/c/d): ");
+        io::stdout().flush()?;
+        io::stdin().read_line(&mut input)?;
+        break match input.trim().to_lowercase().as_str() {
+            "a" | "lib" | "library" => "library",
+            "b" | "compiler" => "compiler",
+            "c" | "llvm" => "llvm",
+            "d" | "user" | "maintainer" => "maintainer",
+            _ => {
+                println!("error: unrecognized option '{}'", input.trim());
+                println!("note: press Ctrl+C to exit");
+                continue;
+            }
+        };
+    };
+    Ok(template.to_owned())
+}
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 46ba14aa67e..788bb5e787b 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -256,7 +256,7 @@ impl Clean<Item> for doctree::Module<'_> {
 
         // determine if we should display the inner contents or
         // the outer `mod` item for the source code.
-        let whence = {
+        let span = {
             let sm = cx.sess().source_map();
             let outer = sm.lookup_char_pos(self.where_outer.lo());
             let inner = sm.lookup_char_pos(self.where_inner.lo());
@@ -272,7 +272,7 @@ impl Clean<Item> for doctree::Module<'_> {
         Item {
             name: Some(name),
             attrs,
-            source: whence.clean(cx),
+            source: span.clean(cx),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
             deprecation: cx.deprecation(self.id).clean(cx),
@@ -912,7 +912,7 @@ impl Clean<Item> for doctree::Function<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
             deprecation: cx.deprecation(self.id).clean(cx),
@@ -1020,7 +1020,7 @@ impl Clean<Item> for doctree::Trait<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs,
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -1044,7 +1044,7 @@ impl Clean<Item> for doctree::TraitAlias<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs,
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -1830,7 +1830,7 @@ impl Clean<Item> for doctree::Struct<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -1850,7 +1850,7 @@ impl Clean<Item> for doctree::Union<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -1880,7 +1880,7 @@ impl Clean<Item> for doctree::Enum<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -1899,7 +1899,7 @@ impl Clean<Item> for doctree::Variant<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             visibility: Inherited,
             stability: cx.stability(self.id).clean(cx),
             deprecation: cx.deprecation(self.id).clean(cx),
@@ -2047,7 +2047,7 @@ impl Clean<Item> for doctree::Typedef<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -2062,7 +2062,7 @@ impl Clean<Item> for doctree::OpaqueTy<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -2093,7 +2093,7 @@ impl Clean<Item> for doctree::Static<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -2114,7 +2114,7 @@ impl Clean<Item> for doctree::Constant<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: def_id.to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -2168,7 +2168,7 @@ impl Clean<Vec<Item>> for doctree::Impl<'_> {
         let make_item = |trait_: Option<Type>, for_: Type, items: Vec<Item>| Item {
             name: None,
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: def_id.to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -2219,7 +2219,7 @@ impl Clean<Vec<Item>> for doctree::ExternCrate<'_> {
         vec![Item {
             name: None,
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: DefId { krate: self.cnum, index: CRATE_DEF_INDEX },
             visibility: self.vis.clean(cx),
             stability: None,
@@ -2284,7 +2284,7 @@ impl Clean<Vec<Item>> for doctree::Import<'_> {
         vec![Item {
             name: None,
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: DefId::local(CRATE_DEF_INDEX),
             visibility: self.vis.clean(cx),
             stability: None,
@@ -2326,7 +2326,7 @@ impl Clean<Item> for doctree::ForeignItem<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
             visibility: self.vis.clean(cx),
             stability: cx.stability(self.id).clean(cx),
@@ -2342,7 +2342,7 @@ impl Clean<Item> for doctree::Macro<'_> {
         Item {
             name: Some(name.clone()),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             visibility: Public,
             stability: cx.stability(self.hid).clean(cx),
             deprecation: cx.deprecation(self.hid).clean(cx),
@@ -2367,7 +2367,7 @@ impl Clean<Item> for doctree::ProcMacro<'_> {
         Item {
             name: Some(self.name.clean(cx)),
             attrs: self.attrs.clean(cx),
-            source: self.whence.clean(cx),
+            source: self.span.clean(cx),
             visibility: Public,
             stability: cx.stability(self.id).clean(cx),
             deprecation: cx.deprecation(self.id).clean(cx),
diff --git a/src/librustdoc/doctree.rs b/src/librustdoc/doctree.rs
index 98125adbdea..cfa51dcf4f1 100644
--- a/src/librustdoc/doctree.rs
+++ b/src/librustdoc/doctree.rs
@@ -89,7 +89,7 @@ pub struct Struct<'hir> {
     pub generics: &'hir hir::Generics<'hir>,
     pub attrs: &'hir [ast::Attribute],
     pub fields: &'hir [hir::StructField<'hir>],
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct Union<'hir> {
@@ -100,7 +100,7 @@ pub struct Union<'hir> {
     pub generics: &'hir hir::Generics<'hir>,
     pub attrs: &'hir [ast::Attribute],
     pub fields: &'hir [hir::StructField<'hir>],
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct Enum<'hir> {
@@ -109,7 +109,7 @@ pub struct Enum<'hir> {
     pub generics: &'hir hir::Generics<'hir>,
     pub attrs: &'hir [ast::Attribute],
     pub id: hir::HirId,
-    pub whence: Span,
+    pub span: Span,
     pub name: Symbol,
 }
 
@@ -118,7 +118,7 @@ pub struct Variant<'hir> {
     pub id: hir::HirId,
     pub attrs: &'hir [ast::Attribute],
     pub def: &'hir hir::VariantData<'hir>,
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct Function<'hir> {
@@ -128,7 +128,7 @@ pub struct Function<'hir> {
     pub name: Symbol,
     pub vis: &'hir hir::Visibility<'hir>,
     pub header: hir::FnHeader,
-    pub whence: Span,
+    pub span: Span,
     pub generics: &'hir hir::Generics<'hir>,
     pub body: hir::BodyId,
 }
@@ -139,7 +139,7 @@ pub struct Typedef<'hir> {
     pub name: Symbol,
     pub id: hir::HirId,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
     pub vis: &'hir hir::Visibility<'hir>,
 }
 
@@ -148,7 +148,7 @@ pub struct OpaqueTy<'hir> {
     pub name: Symbol,
     pub id: hir::HirId,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
     pub vis: &'hir hir::Visibility<'hir>,
 }
 
@@ -161,7 +161,7 @@ pub struct Static<'hir> {
     pub attrs: &'hir [ast::Attribute],
     pub vis: &'hir hir::Visibility<'hir>,
     pub id: hir::HirId,
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct Constant<'hir> {
@@ -171,7 +171,7 @@ pub struct Constant<'hir> {
     pub attrs: &'hir [ast::Attribute],
     pub vis: &'hir hir::Visibility<'hir>,
     pub id: hir::HirId,
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct Trait<'hir> {
@@ -183,7 +183,7 @@ pub struct Trait<'hir> {
     pub bounds: &'hir [hir::GenericBound<'hir>],
     pub attrs: &'hir [ast::Attribute],
     pub id: hir::HirId,
-    pub whence: Span,
+    pub span: Span,
     pub vis: &'hir hir::Visibility<'hir>,
 }
 
@@ -193,7 +193,7 @@ pub struct TraitAlias<'hir> {
     pub bounds: &'hir [hir::GenericBound<'hir>],
     pub attrs: &'hir [ast::Attribute],
     pub id: hir::HirId,
-    pub whence: Span,
+    pub span: Span,
     pub vis: &'hir hir::Visibility<'hir>,
 }
 
@@ -208,7 +208,7 @@ pub struct Impl<'hir> {
     pub for_: &'hir hir::Ty<'hir>,
     pub items: Vec<&'hir hir::ImplItem<'hir>>,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
     pub vis: &'hir hir::Visibility<'hir>,
     pub id: hir::HirId,
 }
@@ -219,7 +219,7 @@ pub struct ForeignItem<'hir> {
     pub name: Symbol,
     pub kind: &'hir hir::ForeignItemKind<'hir>,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
 }
 
 // For Macro we store the DefId instead of the NodeId, since we also create
@@ -229,7 +229,7 @@ pub struct Macro<'hir> {
     pub hid: hir::HirId,
     pub def_id: hir::def_id::DefId,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
     pub matchers: Vec<Span>,
     pub imported_from: Option<Symbol>,
 }
@@ -240,7 +240,7 @@ pub struct ExternCrate<'hir> {
     pub path: Option<String>,
     pub vis: &'hir hir::Visibility<'hir>,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct Import<'hir> {
@@ -250,7 +250,7 @@ pub struct Import<'hir> {
     pub attrs: &'hir [ast::Attribute],
     pub path: &'hir hir::Path<'hir>,
     pub glob: bool,
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub struct ProcMacro<'hir> {
@@ -259,7 +259,7 @@ pub struct ProcMacro<'hir> {
     pub kind: MacroKind,
     pub helpers: Vec<Symbol>,
     pub attrs: &'hir [ast::Attribute],
-    pub whence: Span,
+    pub span: Span,
 }
 
 pub fn struct_type_from_def(vdata: &hir::VariantData<'_>) -> StructType {
diff --git a/src/librustdoc/visit_ast.rs b/src/librustdoc/visit_ast.rs
index ac9f839600b..33578dc0619 100644
--- a/src/librustdoc/visit_ast.rs
+++ b/src/librustdoc/visit_ast.rs
@@ -99,7 +99,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
             attrs: &item.attrs,
             generics,
             fields: sd.fields(),
-            whence: item.span,
+            span: item.span,
         }
     }
 
@@ -120,7 +120,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
             attrs: &item.attrs,
             generics,
             fields: sd.fields(),
-            whence: item.span,
+            span: item.span,
         }
     }
 
@@ -142,14 +142,14 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     id: v.id,
                     attrs: &v.attrs,
                     def: &v.data,
-                    whence: v.span,
+                    span: v.span,
                 })
                 .collect(),
             vis: &it.vis,
             generics,
             attrs: &it.attrs,
             id: it.hir_id,
-            whence: it.span,
+            span: it.span,
         }
     }
 
@@ -208,7 +208,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     kind,
                     helpers,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                 });
             }
             None => {
@@ -218,7 +218,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     attrs: &item.attrs,
                     decl,
                     name,
-                    whence: item.span,
+                    span: item.span,
                     generics,
                     header,
                     body,
@@ -402,7 +402,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     path: orig_name.map(|x| x.to_string()),
                     vis: &item.vis,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                 })
             }
             hir::ItemKind::Use(_, hir::UseKind::ListStem) => {}
@@ -444,7 +444,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     attrs: &item.attrs,
                     path,
                     glob: is_glob,
-                    whence: item.span,
+                    span: item.span,
                 });
             }
             hir::ItemKind::Mod(ref m) => {
@@ -476,7 +476,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     name: ident.name,
                     id: item.hir_id,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                     vis: &item.vis,
                 };
                 om.typedefs.push(t);
@@ -487,7 +487,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     name: ident.name,
                     id: item.hir_id,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                     vis: &item.vis,
                 };
                 om.opaque_tys.push(t);
@@ -500,7 +500,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     id: item.hir_id,
                     name: ident.name,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                     vis: &item.vis,
                 };
                 om.statics.push(s);
@@ -515,7 +515,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                         id: item.hir_id,
                         name: ident.name,
                         attrs: &item.attrs,
-                        whence: item.span,
+                        span: item.span,
                         vis: &item.vis,
                     };
                     om.constants.push(s);
@@ -532,7 +532,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     bounds,
                     id: item.hir_id,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                     vis: &item.vis,
                 };
                 om.traits.push(t);
@@ -544,7 +544,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                     bounds,
                     id: item.hir_id,
                     attrs: &item.attrs,
-                    whence: item.span,
+                    span: item.span,
                     vis: &item.vis,
                 };
                 om.trait_aliases.push(t);
@@ -577,7 +577,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                         items,
                         attrs: &item.attrs,
                         id: item.hir_id,
-                        whence: item.span,
+                        span: item.span,
                         vis: &item.vis,
                     };
                     om.impls.push(i);
@@ -603,7 +603,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
             kind: &item.kind,
             vis: &item.vis,
             attrs: &item.attrs,
-            whence: item.span,
+            span: item.span,
         });
     }
 
@@ -623,7 +623,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
             def_id: self.cx.tcx.hir().local_def_id(def.hir_id).to_def_id(),
             attrs: &def.attrs,
             name: renamed.unwrap_or(def.ident.name),
-            whence: def.span,
+            span: def.span,
             matchers,
             imported_from: None,
         }
diff --git a/src/test/ui/const-generics/infer/cannot-infer-const-args.full.stderr b/src/test/ui/const-generics/infer/cannot-infer-const-args.full.stderr
index 84e75cc3764..b438ed3ad65 100644
--- a/src/test/ui/const-generics/infer/cannot-infer-const-args.full.stderr
+++ b/src/test/ui/const-generics/infer/cannot-infer-const-args.full.stderr
@@ -2,9 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/cannot-infer-const-args.rs:12:5
    |
 LL |     foo();
-   |     ^^^
-   |
-   = note: cannot infer the value of the const parameter `X`
+   |     ^^^ cannot infer the value of const parameter `X` declared on the function `foo`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/const-generics/infer/cannot-infer-const-args.min.stderr b/src/test/ui/const-generics/infer/cannot-infer-const-args.min.stderr
index 84e75cc3764..b438ed3ad65 100644
--- a/src/test/ui/const-generics/infer/cannot-infer-const-args.min.stderr
+++ b/src/test/ui/const-generics/infer/cannot-infer-const-args.min.stderr
@@ -2,9 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/cannot-infer-const-args.rs:12:5
    |
 LL |     foo();
-   |     ^^^
-   |
-   = note: cannot infer the value of the const parameter `X`
+   |     ^^^ cannot infer the value of const parameter `X` declared on the function `foo`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/const-generics/infer/issue-77092.rs b/src/test/ui/const-generics/infer/issue-77092.rs
new file mode 100644
index 00000000000..9a1dd1a8258
--- /dev/null
+++ b/src/test/ui/const-generics/infer/issue-77092.rs
@@ -0,0 +1,16 @@
+#![feature(min_const_generics)]
+
+use std::convert::TryInto;
+
+fn take_array_from_mut<T, const N: usize>(data: &mut [T], start: usize) -> &mut [T; N] {
+    (&mut data[start .. start + N]).try_into().unwrap()
+}
+
+fn main() {
+    let mut arr = [0, 1, 2, 3, 4, 5, 6, 7, 8];
+
+    for i in 1 .. 4 {
+        println!("{:?}", take_array_from_mut(&mut arr, i));
+        //~^ ERROR type annotations needed
+    }
+}
diff --git a/src/test/ui/const-generics/infer/issue-77092.stderr b/src/test/ui/const-generics/infer/issue-77092.stderr
new file mode 100644
index 00000000000..e84ff8baeea
--- /dev/null
+++ b/src/test/ui/const-generics/infer/issue-77092.stderr
@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-77092.rs:13:26
+   |
+LL |         println!("{:?}", take_array_from_mut(&mut arr, i));
+   |                          ^^^^^^^^^^^^^^^^^^^ cannot infer the value of the constant `{_: usize}`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/const-generics/infer/method-chain.full.stderr b/src/test/ui/const-generics/infer/method-chain.full.stderr
index e65bc3f1096..1fb0b23cf11 100644
--- a/src/test/ui/const-generics/infer/method-chain.full.stderr
+++ b/src/test/ui/const-generics/infer/method-chain.full.stderr
@@ -2,9 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/method-chain.rs:21:33
    |
 LL |     Foo.bar().bar().bar().bar().baz();
-   |                                 ^^^
-   |
-   = note: cannot infer the value of the const parameter `N`
+   |                                 ^^^ cannot infer the value of const parameter `N` declared on the associated function `baz`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/const-generics/infer/method-chain.min.stderr b/src/test/ui/const-generics/infer/method-chain.min.stderr
index e65bc3f1096..1fb0b23cf11 100644
--- a/src/test/ui/const-generics/infer/method-chain.min.stderr
+++ b/src/test/ui/const-generics/infer/method-chain.min.stderr
@@ -2,9 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/method-chain.rs:21:33
    |
 LL |     Foo.bar().bar().bar().bar().baz();
-   |                                 ^^^
-   |
-   = note: cannot infer the value of the const parameter `N`
+   |                                 ^^^ cannot infer the value of const parameter `N` declared on the associated function `baz`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/const-generics/infer/uninferred-consts.full.stderr b/src/test/ui/const-generics/infer/uninferred-consts.full.stderr
index e47b6bd5dc6..7a451903e96 100644
--- a/src/test/ui/const-generics/infer/uninferred-consts.full.stderr
+++ b/src/test/ui/const-generics/infer/uninferred-consts.full.stderr
@@ -2,9 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/uninferred-consts.rs:14:9
    |
 LL |     Foo.foo();
-   |         ^^^
-   |
-   = note: cannot infer the value of the const parameter `N`
+   |         ^^^ cannot infer the value of const parameter `N` declared on the associated function `foo`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/const-generics/infer/uninferred-consts.min.stderr b/src/test/ui/const-generics/infer/uninferred-consts.min.stderr
index e47b6bd5dc6..7a451903e96 100644
--- a/src/test/ui/const-generics/infer/uninferred-consts.min.stderr
+++ b/src/test/ui/const-generics/infer/uninferred-consts.min.stderr
@@ -2,9 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/uninferred-consts.rs:14:9
    |
 LL |     Foo.foo();
-   |         ^^^
-   |
-   = note: cannot infer the value of the const parameter `N`
+   |         ^^^ cannot infer the value of const parameter `N` declared on the associated function `foo`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.rs b/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.rs
index e0b9e5f3375..094ae7378bc 100644
--- a/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.rs
+++ b/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.rs
@@ -4,7 +4,7 @@ const extern fn unsize(x: &[u8; 3]) -> &[u8] { x }
 const unsafe extern "C" fn closure() -> fn() { || {} }
 //~^ ERROR function pointers in const fn are unstable
 const unsafe extern fn use_float() { 1.0 + 1.0; }
-//~^ ERROR only int, `bool` and `char` operations are stable in const fn
+//~^ ERROR floating point arithmetic
 const extern "C" fn ptr_cast(val: *const u8) { val as usize; }
 //~^ ERROR casting pointers to integers
 
diff --git a/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.stderr b/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.stderr
index 5ca44b3fa7e..fcc34f358f9 100644
--- a/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.stderr
+++ b/src/test/ui/consts/const-extern-fn/const-extern-fn-min-const-fn.stderr
@@ -7,14 +7,14 @@ LL | const unsafe extern "C" fn closure() -> fn() { || {} }
    = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
-error[E0723]: only int, `bool` and `char` operations are stable in const fn
+error[E0658]: floating point arithmetic is not allowed in constant functions
   --> $DIR/const-extern-fn-min-const-fn.rs:6:38
    |
 LL | const unsafe extern fn use_float() { 1.0 + 1.0; }
    |                                      ^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57241 <https://github.com/rust-lang/rust/issues/57241> for more information
+   = help: add `#![feature(const_fn_floating_point_arithmetic)]` to the crate attributes to enable
 
 error[E0658]: casting pointers to integers in constant functions is unstable
   --> $DIR/const-extern-fn-min-const-fn.rs:8:48
diff --git a/src/test/ui/consts/const_fn_floating_point_arithmetic.gated.stderr b/src/test/ui/consts/const_fn_floating_point_arithmetic.gated.stderr
new file mode 100644
index 00000000000..ae24f8f6500
--- /dev/null
+++ b/src/test/ui/consts/const_fn_floating_point_arithmetic.gated.stderr
@@ -0,0 +1,8 @@
+error: fatal error triggered by #[rustc_error]
+  --> $DIR/const_fn_floating_point_arithmetic.rs:20:1
+   |
+LL | fn main() {}
+   | ^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/consts/const_fn_floating_point_arithmetic.rs b/src/test/ui/consts/const_fn_floating_point_arithmetic.rs
new file mode 100644
index 00000000000..5e32482b21a
--- /dev/null
+++ b/src/test/ui/consts/const_fn_floating_point_arithmetic.rs
@@ -0,0 +1,20 @@
+// gate-test-const_fn_floating_point_arithmetic
+
+// revisions: stock gated
+
+#![feature(rustc_attrs)]
+#![cfg_attr(gated, feature(const_fn_floating_point_arithmetic))]
+
+const fn add(f: f32) -> f32 { f + 2.0 }
+//[stock]~^ floating point arithmetic
+const fn sub(f: f32) -> f32 { 2.0 - f }
+//[stock]~^ floating point arithmetic
+const fn mul(f: f32, g: f32) -> f32 { f * g }
+//[stock]~^ floating point arithmetic
+const fn div(f: f32, g: f32) -> f32 { f / g }
+//[stock]~^ floating point arithmetic
+const fn neg(f: f32) -> f32 { -f }
+//[stock]~^ floating point arithmetic
+
+#[rustc_error]
+fn main() {} //[gated]~ fatal error triggered by #[rustc_error]
diff --git a/src/test/ui/consts/const_fn_floating_point_arithmetic.stock.stderr b/src/test/ui/consts/const_fn_floating_point_arithmetic.stock.stderr
new file mode 100644
index 00000000000..ef7a60faf3f
--- /dev/null
+++ b/src/test/ui/consts/const_fn_floating_point_arithmetic.stock.stderr
@@ -0,0 +1,48 @@
+error[E0658]: floating point arithmetic is not allowed in constant functions
+  --> $DIR/const_fn_floating_point_arithmetic.rs:8:31
+   |
+LL | const fn add(f: f32) -> f32 { f + 2.0 }
+   |                               ^^^^^^^
+   |
+   = note: see issue #57241 <https://github.com/rust-lang/rust/issues/57241> for more information
+   = help: add `#![feature(const_fn_floating_point_arithmetic)]` to the crate attributes to enable
+
+error[E0658]: floating point arithmetic is not allowed in constant functions
+  --> $DIR/const_fn_floating_point_arithmetic.rs:10:31
+   |
+LL | const fn sub(f: f32) -> f32 { 2.0 - f }
+   |                               ^^^^^^^
+   |
+   = note: see issue #57241 <https://github.com/rust-lang/rust/issues/57241> for more information
+   = help: add `#![feature(const_fn_floating_point_arithmetic)]` to the crate attributes to enable
+
+error[E0658]: floating point arithmetic is not allowed in constant functions
+  --> $DIR/const_fn_floating_point_arithmetic.rs:12:39
+   |
+LL | const fn mul(f: f32, g: f32) -> f32 { f * g }
+   |                                       ^^^^^
+   |
+   = note: see issue #57241 <https://github.com/rust-lang/rust/issues/57241> for more information
+   = help: add `#![feature(const_fn_floating_point_arithmetic)]` to the crate attributes to enable
+
+error[E0658]: floating point arithmetic is not allowed in constant functions
+  --> $DIR/const_fn_floating_point_arithmetic.rs:14:39
+   |
+LL | const fn div(f: f32, g: f32) -> f32 { f / g }
+   |                                       ^^^^^
+   |
+   = note: see issue #57241 <https://github.com/rust-lang/rust/issues/57241> for more information
+   = help: add `#![feature(const_fn_floating_point_arithmetic)]` to the crate attributes to enable
+
+error[E0658]: floating point arithmetic is not allowed in constant functions
+  --> $DIR/const_fn_floating_point_arithmetic.rs:16:31
+   |
+LL | const fn neg(f: f32) -> f32 { -f }
+   |                               ^^
+   |
+   = note: see issue #57241 <https://github.com/rust-lang/rust/issues/57241> for more information
+   = help: add `#![feature(const_fn_floating_point_arithmetic)]` to the crate attributes to enable
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const_let_eq_float.rs b/src/test/ui/consts/const_let_eq_float.rs
index bc0ef26eb2f..e15f4b804f7 100644
--- a/src/test/ui/consts/const_let_eq_float.rs
+++ b/src/test/ui/consts/const_let_eq_float.rs
@@ -1,6 +1,6 @@
-// build-pass (FIXME(62277): could be check-pass?)
+// run-pass
 
-#![feature(const_fn)]
+#![feature(const_fn_floating_point_arithmetic)]
 
 struct Foo<T>(T);
 struct Bar<T> { x: T }
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.rs b/src/test/ui/consts/min_const_fn/min_const_fn.rs
index 336d754b06a..55a999d5cdc 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.rs
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.rs
@@ -77,14 +77,6 @@ const fn foo11<T: std::fmt::Display>(t: T) -> T { t }
 //~^ ERROR trait bounds other than `Sized` on const fn parameters are unstable
 const fn foo11_2<T: Send>(t: T) -> T { t }
 //~^ ERROR trait bounds other than `Sized` on const fn parameters are unstable
-const fn foo19(f: f32) -> f32 { f * 2.0 }
-//~^ ERROR int, `bool` and `char` operations
-const fn foo19_2(f: f32) -> f32 { 2.0 - f }
-//~^ ERROR int, `bool` and `char` operations
-const fn foo19_3(f: f32) -> f32 { -f }
-//~^ ERROR int, `bool` and `char` operations
-const fn foo19_4(f: f32, g: f32) -> f32 { f / g }
-//~^ ERROR int, `bool` and `char` operations
 
 static BAR: u32 = 42;
 const fn foo25() -> u32 { BAR } //~ ERROR cannot refer to statics
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.stderr b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
index c96500e38ec..a37e5203eee 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
@@ -76,44 +76,8 @@ LL | const fn foo11_2<T: Send>(t: T) -> T { t }
    = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
-error[E0723]: only int, `bool` and `char` operations are stable in const fn
-  --> $DIR/min_const_fn.rs:80:33
-   |
-LL | const fn foo19(f: f32) -> f32 { f * 2.0 }
-   |                                 ^^^^^^^
-   |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
-
-error[E0723]: only int, `bool` and `char` operations are stable in const fn
-  --> $DIR/min_const_fn.rs:82:35
-   |
-LL | const fn foo19_2(f: f32) -> f32 { 2.0 - f }
-   |                                   ^^^^^^^
-   |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
-
-error[E0723]: only int, `bool` and `char` operations are stable in const fn
-  --> $DIR/min_const_fn.rs:84:35
-   |
-LL | const fn foo19_3(f: f32) -> f32 { -f }
-   |                                   ^^
-   |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
-
-error[E0723]: only int, `bool` and `char` operations are stable in const fn
-  --> $DIR/min_const_fn.rs:86:43
-   |
-LL | const fn foo19_4(f: f32, g: f32) -> f32 { f / g }
-   |                                           ^^^^^
-   |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
-
 error[E0013]: constant functions cannot refer to statics
-  --> $DIR/min_const_fn.rs:90:27
+  --> $DIR/min_const_fn.rs:82:27
    |
 LL | const fn foo25() -> u32 { BAR }
    |                           ^^^
@@ -121,7 +85,7 @@ LL | const fn foo25() -> u32 { BAR }
    = help: consider extracting the value of the `static` to a `const`, and referring to that
 
 error[E0013]: constant functions cannot refer to statics
-  --> $DIR/min_const_fn.rs:91:37
+  --> $DIR/min_const_fn.rs:83:37
    |
 LL | const fn foo26() -> &'static u32 { &BAR }
    |                                     ^^^
@@ -129,7 +93,7 @@ LL | const fn foo26() -> &'static u32 { &BAR }
    = help: consider extracting the value of the `static` to a `const`, and referring to that
 
 error[E0658]: casting pointers to integers in constant functions is unstable
-  --> $DIR/min_const_fn.rs:92:42
+  --> $DIR/min_const_fn.rs:84:42
    |
 LL | const fn foo30(x: *const u32) -> usize { x as usize }
    |                                          ^^^^^^^^^^
@@ -138,7 +102,7 @@ LL | const fn foo30(x: *const u32) -> usize { x as usize }
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
 error[E0658]: casting pointers to integers in constant functions is unstable
-  --> $DIR/min_const_fn.rs:94:63
+  --> $DIR/min_const_fn.rs:86:63
    |
 LL | const fn foo30_with_unsafe(x: *const u32) -> usize { unsafe { x as usize } }
    |                                                               ^^^^^^^^^^
@@ -147,7 +111,7 @@ LL | const fn foo30_with_unsafe(x: *const u32) -> usize { unsafe { x as usize }
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
 error[E0658]: casting pointers to integers in constant functions is unstable
-  --> $DIR/min_const_fn.rs:96:42
+  --> $DIR/min_const_fn.rs:88:42
    |
 LL | const fn foo30_2(x: *mut u32) -> usize { x as usize }
    |                                          ^^^^^^^^^^
@@ -156,7 +120,7 @@ LL | const fn foo30_2(x: *mut u32) -> usize { x as usize }
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
 error[E0658]: casting pointers to integers in constant functions is unstable
-  --> $DIR/min_const_fn.rs:98:63
+  --> $DIR/min_const_fn.rs:90:63
    |
 LL | const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize } }
    |                                                               ^^^^^^^^^^
@@ -165,7 +129,7 @@ LL | const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize }
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
 error[E0658]: mutable references are not allowed in constant functions
-  --> $DIR/min_const_fn.rs:101:14
+  --> $DIR/min_const_fn.rs:93:14
    |
 LL | const fn inc(x: &mut i32) { *x += 1 }
    |              ^
@@ -174,7 +138,7 @@ LL | const fn inc(x: &mut i32) { *x += 1 }
    = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:110:6
+  --> $DIR/min_const_fn.rs:102:6
    |
 LL | impl<T: std::fmt::Debug> Foo<T> {
    |      ^
@@ -183,7 +147,7 @@ LL | impl<T: std::fmt::Debug> Foo<T> {
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:115:6
+  --> $DIR/min_const_fn.rs:107:6
    |
 LL | impl<T: std::fmt::Debug + Sized> Foo<T> {
    |      ^
@@ -192,7 +156,7 @@ LL | impl<T: std::fmt::Debug + Sized> Foo<T> {
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:120:6
+  --> $DIR/min_const_fn.rs:112:6
    |
 LL | impl<T: Sync + Sized> Foo<T> {
    |      ^
@@ -201,7 +165,7 @@ LL | impl<T: Sync + Sized> Foo<T> {
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:126:34
+  --> $DIR/min_const_fn.rs:118:34
    |
 LL | const fn no_apit2(_x: AlanTuring<impl std::fmt::Debug>) {}
    |                                  ^^^^^^^^^^^^^^^^^^^^
@@ -210,7 +174,7 @@ LL | const fn no_apit2(_x: AlanTuring<impl std::fmt::Debug>) {}
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:128:22
+  --> $DIR/min_const_fn.rs:120:22
    |
 LL | const fn no_apit(_x: impl std::fmt::Debug) {}
    |                      ^^^^^^^^^^^^^^^^^^^^
@@ -219,7 +183,7 @@ LL | const fn no_apit(_x: impl std::fmt::Debug) {}
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:129:23
+  --> $DIR/min_const_fn.rs:121:23
    |
 LL | const fn no_dyn_trait(_x: &dyn std::fmt::Debug) {}
    |                       ^^
@@ -228,7 +192,7 @@ LL | const fn no_dyn_trait(_x: &dyn std::fmt::Debug) {}
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:130:32
+  --> $DIR/min_const_fn.rs:122:32
    |
 LL | const fn no_dyn_trait_ret() -> &'static dyn std::fmt::Debug { &() }
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -237,7 +201,7 @@ LL | const fn no_dyn_trait_ret() -> &'static dyn std::fmt::Debug { &() }
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
-  --> $DIR/min_const_fn.rs:135:41
+  --> $DIR/min_const_fn.rs:127:41
    |
 LL | const fn really_no_traits_i_mean_it() { (&() as &dyn std::fmt::Debug, ()).1 }
    |                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -246,7 +210,7 @@ LL | const fn really_no_traits_i_mean_it() { (&() as &dyn std::fmt::Debug, ()).1
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: function pointers in const fn are unstable
-  --> $DIR/min_const_fn.rs:138:21
+  --> $DIR/min_const_fn.rs:130:21
    |
 LL | const fn no_fn_ptrs(_x: fn()) {}
    |                     ^^
@@ -255,7 +219,7 @@ LL | const fn no_fn_ptrs(_x: fn()) {}
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
 error[E0723]: function pointers in const fn are unstable
-  --> $DIR/min_const_fn.rs:140:27
+  --> $DIR/min_const_fn.rs:132:27
    |
 LL | const fn no_fn_ptrs2() -> fn() { fn foo() {} foo }
    |                           ^^^^
@@ -263,7 +227,7 @@ LL | const fn no_fn_ptrs2() -> fn() { fn foo() {} foo }
    = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
    = help: add `#![feature(const_fn)]` to the crate attributes to enable
 
-error: aborting due to 30 previous errors
+error: aborting due to 26 previous errors
 
 Some errors have detailed explanations: E0013, E0493, E0658, E0723.
 For more information about an error, try `rustc --explain E0013`.
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.rs b/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.rs
index b83fdf7c656..292e2dd167c 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.rs
+++ b/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.rs
@@ -3,7 +3,7 @@
             we're apparently really bad at it",
             issue = "none")]
 
-#![feature(const_fn, foo, foo2)]
+#![feature(const_fn, const_fn_floating_point_arithmetic, foo, foo2)]
 #![feature(staged_api)]
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -25,9 +25,9 @@ const fn bar2() -> u32 { foo2() } //~ ERROR not yet stable as a const fn
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_stable(feature = "rust1", since = "1.0.0")]
-// conformity is required, even with `const_fn` feature gate
+// Const-stable functions cannot rely on unstable const-eval features.
 const fn bar3() -> u32 { (5f32 + 6f32) as u32 }
-//~^ ERROR const-stable function cannot use `#[feature(const_fn)]`
+//~^ ERROR const-stable function cannot use `#[feature(const_fn_floating_point_arithmetic)]`
 
 // check whether this function cannot be called even with the feature gate active
 #[unstable(feature = "foo2", issue = "none")]
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.stderr b/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.stderr
index a1f1f6f52ab..fa2260b40d1 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_fn_libstd_stability.stderr
@@ -14,7 +14,7 @@ LL | const fn bar2() -> u32 { foo2() }
    |
    = help: Const-stable functions can only call other const-stable functions
 
-error: const-stable function cannot use `#[feature(const_fn)]`
+error: const-stable function cannot use `#[feature(const_fn_floating_point_arithmetic)]`
   --> $DIR/min_const_fn_libstd_stability.rs:29:26
    |
 LL | const fn bar3() -> u32 { (5f32 + 6f32) as u32 }
diff --git a/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.rs b/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.rs
index 902ed435e31..0f48341ddf3 100644
--- a/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.rs
+++ b/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.rs
@@ -3,7 +3,7 @@
             we're apparently really bad at it",
             issue = "none")]
 
-#![feature(const_fn, foo, foo2)]
+#![feature(const_fn, const_fn_floating_point_arithmetic, foo, foo2)]
 #![feature(staged_api)]
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -27,7 +27,7 @@ const unsafe fn bar2() -> u32 { unsafe { foo2() } } //~ ERROR not yet stable as
 #[rustc_const_stable(feature = "rust1", since = "1.0.0")]
 // conformity is required, even with `const_fn` feature gate
 const unsafe fn bar3() -> u32 { (5f32 + 6f32) as u32 }
-//~^ ERROR const-stable function cannot use `#[feature(const_fn)]`
+//~^ ERROR const-stable function cannot use `#[feature(const_fn_floating_point_arithmetic)]`
 
 // check whether this function cannot be called even with the feature gate active
 #[unstable(feature = "foo2", issue = "none")]
diff --git a/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.stderr b/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.stderr
index 2741a864404..1ca5964ce0f 100644
--- a/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_unsafe_fn_libstd_stability.stderr
@@ -14,7 +14,7 @@ LL | const unsafe fn bar2() -> u32 { unsafe { foo2() } }
    |
    = help: Const-stable functions can only call other const-stable functions
 
-error: const-stable function cannot use `#[feature(const_fn)]`
+error: const-stable function cannot use `#[feature(const_fn_floating_point_arithmetic)]`
   --> $DIR/min_const_unsafe_fn_libstd_stability.rs:29:33
    |
 LL | const unsafe fn bar3() -> u32 { (5f32 + 6f32) as u32 }
diff --git a/src/tools/miri b/src/tools/miri
-Subproject 02a33d411d8e385942776760a99535d69826349
+Subproject 2f84bfc57dd0ef22269bb84dae10f71e5e23e85
diff --git a/src/tools/rustbook/Cargo.toml b/src/tools/rustbook/Cargo.toml
index f0a6ce2fa06..f5e5c0867b4 100644
--- a/src/tools/rustbook/Cargo.toml
+++ b/src/tools/rustbook/Cargo.toml
@@ -9,6 +9,6 @@ edition = "2018"
 clap = "2.25.0"
 
 [dependencies.mdbook]
-version = "0.4.0"
+version = "0.4.3"
 default-features = false
 features = ["search"]