Auto merge of #115137 - GuillaumeGomez:rollup-37jqoyg, r=GuillaumeGomez

Rollup of 6 pull requests

Successful merges:

 - #114696 (Fix a pthread_t handle leak #114610)
 - #115102 (Improve note for the `invalid_reference_casting` lint)
 - #115103 (Disable bootstrap rustc version check)
 - #115106 (ArchiveWrapper: handle LLVM API update)
 - #115109 (Skip ExpandYamlAnchors when the config is missing)
 - #115135 (Rustdoc: Add unstable --no-html-source flag)

r? `@ghost`
`@rustbot` modify labels: rollup

13 files changed, 123 insertions, 2 deletions

diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index c4a7f717840..d7cb159149d 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -323,6 +323,8 @@ lint_invalid_reference_casting_assign_to_ref = assigning to `&T` is undefined be
 lint_invalid_reference_casting_borrow_as_mut = casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
     .label = casting happend here
 
+lint_invalid_reference_casting_note_book = for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
+
 lint_lintpass_by_hand = implementing `LintPass` by hand
     .help = try using `declare_lint_pass!` or `impl_lint_pass!` instead
 
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 25982a45853..993c576d697 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -764,11 +764,13 @@ pub enum InvalidFromUtf8Diag {
 #[derive(LintDiagnostic)]
 pub enum InvalidReferenceCastingDiag {
     #[diag(lint_invalid_reference_casting_borrow_as_mut)]
+    #[note(lint_invalid_reference_casting_note_book)]
     BorrowAsMut {
         #[label]
         orig_cast: Option<Span>,
     },
     #[diag(lint_invalid_reference_casting_assign_to_ref)]
+    #[note(lint_invalid_reference_casting_note_book)]
     AssignToRef {
         #[label]
         orig_cast: Option<Span>,
diff --git a/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp
index 35d6b9ed7a4..54fdc84c77d 100644
--- a/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp
@@ -203,7 +203,12 @@ LLVMRustWriteArchive(char *Dst, size_t NumMembers,
     }
   }
 
+#if LLVM_VERSION_LT(18, 0)
   auto Result = writeArchive(Dst, Members, WriteSymbtab, Kind, true, false);
+#else
+  auto SymtabMode = WriteSymbtab ? SymtabWritingMode::NormalSymtab : SymtabWritingMode::NoSymtab;
+  auto Result = writeArchive(Dst, Members, SymtabMode, Kind, true, false);
+#endif
   if (!Result)
     return LLVMRustResult::Success;
   LLVMRustSetLastError(toString(std::move(Result)).c_str());
diff --git a/library/std/src/sys/wasi/thread.rs b/library/std/src/sys/wasi/thread.rs
index dbad425976a..a0eefa8811a 100644
--- a/library/std/src/sys/wasi/thread.rs
+++ b/library/std/src/sys/wasi/thread.rs
@@ -47,12 +47,20 @@ cfg_if::cfg_if! {
                     stack_size: libc::size_t,
                 ) -> ffi::c_int;
                 pub fn pthread_attr_destroy(attr: *mut pthread_attr_t) -> ffi::c_int;
+                pub fn pthread_detach(thread: pthread_t) -> ffi::c_int;
             }
         }
 
         pub struct Thread {
             id: libc::pthread_t,
         }
+
+        impl Drop for Thread {
+            fn drop(&mut self) {
+                let ret = unsafe { libc::pthread_detach(self.id) };
+                debug_assert_eq!(ret, 0);
+            }
+        }
     } else {
         pub struct Thread(!);
     }
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 4821d20a898..762e66ac7cc 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -1276,7 +1276,8 @@ impl Config {
         }
 
         config.initial_rustc = if let Some(rustc) = build.rustc {
-            config.check_build_rustc_version(&rustc);
+            // FIXME(#115065): re-enable this check
+            // config.check_build_rustc_version(&rustc);
             PathBuf::from(rustc)
         } else {
             config.download_beta_toolchain();
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index db3b7ffbea4..d1018978f78 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1174,6 +1174,11 @@ impl Step for ExpandYamlAnchors {
     /// appropriate configuration for all our CI providers. This step ensures the tool was called
     /// by the user before committing CI changes.
     fn run(self, builder: &Builder<'_>) {
+        // Note: `.github/` is not included in dist-src tarballs
+        if !builder.src.join(".github/workflows/ci.yml").exists() {
+            builder.info("Skipping YAML anchors check: GitHub Actions config not found");
+            return;
+        }
         builder.info("Ensuring the YAML anchors in the GitHub Actions config were expanded");
         builder.run_delaying_failure(
             &mut builder.tool_cmd(Tool::ExpandYamlAnchors).arg("check").arg(&builder.src),
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 81fb13f4166..1ce7efdfc20 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -273,6 +273,8 @@ pub(crate) struct RenderOptions {
     pub(crate) call_locations: AllCallLocations,
     /// If `true`, Context::init will not emit shared files.
     pub(crate) no_emit_shared: bool,
+    /// If `true`, HTML source code pages won't be generated.
+    pub(crate) html_no_source: bool,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -686,6 +688,7 @@ impl Options {
         let generate_link_to_definition = matches.opt_present("generate-link-to-definition");
         let extern_html_root_takes_precedence =
             matches.opt_present("extern-html-root-takes-precedence");
+        let html_no_source = matches.opt_present("html-no-source");
 
         if generate_link_to_definition && (show_coverage || output_format != OutputFormat::Html) {
             diag.struct_err(
@@ -769,6 +772,7 @@ impl Options {
             generate_link_to_definition,
             call_locations,
             no_emit_shared: false,
+            html_no_source,
         };
         Ok((options, render_options))
     }
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index d7ff248a9bf..bb1c186668c 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -463,6 +463,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             generate_link_to_definition,
             call_locations,
             no_emit_shared,
+            html_no_source,
             ..
         } = options;
 
@@ -488,7 +489,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             scrape_examples_extension: !call_locations.is_empty(),
         };
         let mut issue_tracker_base_url = None;
-        let mut include_sources = true;
+        let mut include_sources = !html_no_source;
 
         // Crawl the crate attributes looking for attributes which control how we're
         // going to emit HTML
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 8220df5d4f3..92e06f3ab0f 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -656,6 +656,9 @@ fn opts() -> Vec<RustcOptGroup> {
                 "[rust]",
             )
         }),
+        unstable("html-no-source", |o| {
+            o.optflag("", "html-no-source", "Disable HTML source code pages generation")
+        }),
     ]
 }
 
diff --git a/tests/run-make/issue-88756-default-output/output-default.stdout b/tests/run-make/issue-88756-default-output/output-default.stdout
index b280698230d..de8ff0e5f89 100644
--- a/tests/run-make/issue-88756-default-output/output-default.stdout
+++ b/tests/run-make/issue-88756-default-output/output-default.stdout
@@ -191,6 +191,8 @@ Options:
                         removed, see issue #44136
                         <https://github.com/rust-lang/rust/issues/44136> for
                         more information
+        --html-no-source 
+                        Disable HTML source code pages generation
 
     @path               Read newline separated options from `path`
 
diff --git a/tests/rustdoc/html-no-source.rs b/tests/rustdoc/html-no-source.rs
new file mode 100644
index 00000000000..25615a73c3f
--- /dev/null
+++ b/tests/rustdoc/html-no-source.rs
@@ -0,0 +1,30 @@
+// compile-flags: -Zunstable-options --html-no-source
+
+// This test ensures that the `--html-no-source` flag disables
+// the creation of the `src` folder.
+
+#![feature(staged_api)]
+#![stable(feature = "bar", since = "1.0")]
+#![crate_name = "foo"]
+
+// Ensures that there is no items in the corresponding "src" folder.
+// @files 'src/foo' '[]'
+
+// @has foo/fn.foo.html
+// @has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · '
+// @!has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · source · '
+#[stable(feature = "bar", since = "1.0")]
+pub fn foo() {}
+
+// @has foo/struct.Bar.html
+// @has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · '
+// @!has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · source · '
+#[stable(feature = "bar", since = "1.0")]
+pub struct Bar;
+
+impl Bar {
+    // @has - '//*[@id="method.bar"]/*[@class="since rightside"]' '2.0'
+    // @!has - '//*[@id="method.bar"]/*[@class="rightside"]' '2.0 ·'
+    #[stable(feature = "foobar", since = "2.0")]
+    pub fn bar() {}
+}
diff --git a/tests/ui/const-generics/issues/issue-100313.stderr b/tests/ui/const-generics/issues/issue-100313.stderr
index 42ad4d61c8e..796966b22d5 100644
--- a/tests/ui/const-generics/issues/issue-100313.stderr
+++ b/tests/ui/const-generics/issues/issue-100313.stderr
@@ -4,6 +4,7 @@ error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
 LL |             *(B as *const bool as *mut bool) = false;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
    = note: `#[deny(invalid_reference_casting)]` on by default
 
 error[E0080]: evaluation of constant value failed
diff --git a/tests/ui/lint/reference_casting.stderr b/tests/ui/lint/reference_casting.stderr
index c1589f13835..47b95460ec3 100644
--- a/tests/ui/lint/reference_casting.stderr
+++ b/tests/ui/lint/reference_casting.stderr
@@ -4,6 +4,7 @@ error: casting `&T` to `&mut T` is undefined behavior, even if the reference is
 LL |     let _num = &mut *(num as *const i32 as *mut i32);
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
    = note: `#[deny(invalid_reference_casting)]` on by default
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
@@ -11,54 +12,72 @@ error: casting `&T` to `&mut T` is undefined behavior, even if the reference is
    |
 LL |     let _num = &mut *(num as *const i32).cast_mut();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:23:16
    |
 LL |     let _num = &mut *std::ptr::from_ref(num).cast_mut();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:25:16
    |
 LL |     let _num = &mut *std::ptr::from_ref({ num }).cast_mut();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:27:16
    |
 LL |     let _num = &mut *{ std::ptr::from_ref(num) }.cast_mut();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:29:16
    |
 LL |     let _num = &mut *(std::ptr::from_ref({ num }) as *mut i32);
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:31:16
    |
 LL |     let _num = &mut *(num as *const i32).cast::<i32>().cast_mut();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:33:16
    |
 LL |     let _num = &mut *(num as *const i32).cast::<i32>().cast_mut().cast_const().cast_mut();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:35:16
    |
 LL |     let _num = &mut *(std::ptr::from_ref(static_u8()) as *mut i32);
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:37:16
    |
 LL |     let _num = &mut *std::mem::transmute::<_, *mut i32>(num);
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:41:16
@@ -67,6 +86,8 @@ LL |     let deferred = num as *const i32 as *mut i32;
    |                    ----------------------------- casting happend here
 LL |     let _num = &mut *deferred;
    |                ^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:44:16
@@ -75,60 +96,80 @@ LL |     let deferred = (std::ptr::from_ref(num) as *const i32 as *const i32).ca
    |                    ---------------------------------------------------------------------------- casting happend here
 LL |     let _num = &mut *deferred;
    |                ^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:46:16
    |
 LL |     let _num = &mut *(num as *const _ as usize as *mut i32);
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
   --> $DIR/reference_casting.rs:50:9
    |
 LL |         &mut *((this as *const _) as *mut _)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:60:5
    |
 LL |     *(a as *const _ as *mut _) = String::from("Replaced");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:62:5
    |
 LL |     *(a as *const _ as *mut String) += " world";
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:64:5
    |
 LL |     *std::ptr::from_ref(num).cast_mut() += 1;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:66:5
    |
 LL |     *std::ptr::from_ref({ num }).cast_mut() += 1;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:68:5
    |
 LL |     *{ std::ptr::from_ref(num) }.cast_mut() += 1;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:70:5
    |
 LL |     *(std::ptr::from_ref({ num }) as *mut i32) += 1;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:72:5
    |
 LL |     *std::mem::transmute::<_, *mut i32>(num) += 1;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:74:5
@@ -139,6 +180,8 @@ LL | |         std::mem::transmute::<*const i32, *mut i32>(num),
 LL | |         -1i32,
 LL | |     );
    | |_____^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:81:5
@@ -147,18 +190,24 @@ LL |     let value = num as *const i32 as *mut i32;
    |                 ----------------------------- casting happend here
 LL |     *value = 1;
    |     ^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:83:5
    |
 LL |     *(num as *const i32).cast::<i32>().cast_mut() = 2;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:85:5
    |
 LL |     *(num as *const _ as usize as *mut i32) = 2;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:87:5
@@ -168,6 +217,8 @@ LL |     let value = num as *const i32 as *mut i32;
 ...
 LL |     std::ptr::write(value, 2);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:89:5
@@ -177,6 +228,8 @@ LL |     let value = num as *const i32 as *mut i32;
 ...
 LL |     std::ptr::write_unaligned(value, 2);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:91:5
@@ -186,12 +239,16 @@ LL |     let value = num as *const i32 as *mut i32;
 ...
 LL |     std::ptr::write_volatile(value, 2);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
   --> $DIR/reference_casting.rs:95:9
    |
 LL |         *(this as *const _ as *mut _) = a;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
 
 error: aborting due to 29 previous errors