Auto merge of #113083 - matthiaskrgr:rollup-anbqpij, r=matthiaskrgr

Rollup of 3 pull requests

Successful merges:

 - #113039 (make custom mir ICE a bit nicer)
 - #113058 (Add/improve code comments)
 - #113063 (Update books)

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

Author: bors

compiler/rustc_mir_build/src/build/custom/mod.rs

@@ -118,7 +118,11 @@ fn parse_attribute(attr: &Attribute) -> MirPhase {
                 phase = Some(value);
             }
             other => {
-                panic!("Unexpected key {}", other);
+                span_bug!(
+                    nested.span(),
+                    "Unexpected key while parsing custom_mir attribute: '{}'",
+                    other
+                );
             }
         }
     }

src/doc/book

@@ -2355,7 +2355,7 @@ fn filter_tokens_from_list(
     tokens
 }
 
-/// When inlining items, we merge its attributes (and all the reexports attributes too) with the
+/// When inlining items, we merge their attributes (and all the reexports attributes too) with the
 /// final reexport. For example:
 ///
 /// ```ignore (just an example)

src/doc/nomicon

@@ -956,6 +956,8 @@ pub(crate) trait AttributesExt {
                     .filter_map(|attr| Cfg::parse(attr.meta_item()?).ok())
                     .fold(Cfg::True, |cfg, new_cfg| cfg & new_cfg)
             } else if doc_auto_cfg_active {
+                // If there is no `doc(cfg())`, then we retrieve the `cfg()` attributes (because
+                // `doc(cfg())` overrides `cfg()`).
                 self.iter()
                     .filter(|attr| attr.has_name(sym::cfg))
                     .filter_map(|attr| single(attr.meta_item_list()?))
@@ -2387,6 +2389,7 @@ impl ImplKind {
 #[derive(Clone, Debug)]
 pub(crate) struct Import {
     pub(crate) kind: ImportKind,
+    /// The item being re-exported.
     pub(crate) source: ImportSource,
     pub(crate) should_be_displayed: bool,
 }

src/doc/reference

@@ -1,4 +1,4 @@
-// This test ensures that a re-export of  `#[doc(hidden)]` item inside a private
+// This test ensures that a re-export of `#[doc(hidden)]` item inside a private
 // module will still be displayed (the re-export, not the item).
 
 #![crate_name = "foo"]