Auto merge of #68861 - Dylan-DPC:rollup-0m09hsg, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - #68762 (Strip unnecessary subexpression)
 - #68790 (Improve `merge_from_succ`)
 - #68809 (Make more arithmetic functions unstably const)
 - #68832 (Clean up E0264, E0267 and E0268 explanations)
 - #68840 (On suggesting `#![recursion_limit = "X"]`, note current crate name)
 - #68846 (doc fix on doc attribute)
 - #68851 (Fix issue number of `capacity` method)
 - #68858 (Merge item id stable hashing functions)

Failed merges:

r? @ghost

3 files changed, 11 insertions, 6 deletions

diff --git a/src/librustc_error_codes/error_codes/E0264.md b/src/librustc_error_codes/error_codes/E0264.md
index e1e7516cec2..708eac8837a 100644
--- a/src/librustc_error_codes/error_codes/E0264.md
+++ b/src/librustc_error_codes/error_codes/E0264.md
@@ -1,4 +1,6 @@
-An unknown external lang item was used. Erroneous code example:
+An unknown external lang item was used.
+
+Erroneous code example:
 
 ```compile_fail,E0264
 #![feature(lang_items)]
diff --git a/src/librustc_error_codes/error_codes/E0267.md b/src/librustc_error_codes/error_codes/E0267.md
index 066ebee0ffb..951490df874 100644
--- a/src/librustc_error_codes/error_codes/E0267.md
+++ b/src/librustc_error_codes/error_codes/E0267.md
@@ -1,5 +1,7 @@
-This error indicates the use of a loop keyword (`break` or `continue`) inside a
-closure but outside of any loop. Erroneous code example:
+A loop keyword (`break` or `continue`) was used inside a closure but outside of
+any loop.
+
+Erroneous code example:
 
 ```compile_fail,E0267
 let w = || { break; }; // error: `break` inside of a closure
diff --git a/src/librustc_error_codes/error_codes/E0268.md b/src/librustc_error_codes/error_codes/E0268.md
index 7f3ac118601..436aef79fe0 100644
--- a/src/librustc_error_codes/error_codes/E0268.md
+++ b/src/librustc_error_codes/error_codes/E0268.md
@@ -1,6 +1,6 @@
-This error indicates the use of a loop keyword (`break` or `continue`) outside
-of a loop. Without a loop to break out of or continue in, no sensible action can
-be taken. Erroneous code example:
+A loop keyword (`break` or `continue`) was used outside of a loop.
+
+Erroneous code example:
 
 ```compile_fail,E0268
 fn some_func() {
@@ -8,6 +8,7 @@ fn some_func() {
 }
 ```
 
+Without a loop to break out of or continue in, no sensible action can be taken.
 Please verify that you are using `break` and `continue` only in loops. Example:
 
 ```