Auto merge of #125120 - compiler-errors:rollup-mnjybwv, r=compiler-errors

Rollup of 7 pull requests

Successful merges:

 - #119838 (style-guide: When breaking binops handle multi-line first operand better)
 - #124844 (Use a proper probe for shadowing impl)
 - #125047 (Migrate `run-make/issue-14500` to new `rmake.rs` format)
 - #125080 (only find segs chain for missing methods when no available candidates)
 - #125088 (Uplift `AliasTy` and `AliasTerm`)
 - #125100 (Don't do post-method-probe error reporting steps if we're in a suggestion)
 - #125118 (Use new utility functions/methods in run-make tests)

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

2 files changed, 33 insertions, 0 deletions

diff --git a/src/doc/style-guide/src/editions.md b/src/doc/style-guide/src/editions.md
index 9d593f80810..74e873e35ff 100644
--- a/src/doc/style-guide/src/editions.md
+++ b/src/doc/style-guide/src/editions.md
@@ -40,6 +40,8 @@ include:
   of a delimited expression, delimited expressions are generally combinable,
   regardless of the number of members. Previously only applied with exactly
   one member (except for closures with explicit blocks).
+- When line-breaking a binary operator, if the first operand spans multiple
+  lines, use the base indentation of the last line.
 - Miscellaneous `rustfmt` bugfixes.
 - Use version-sort (sort `x8`, `x16`, `x32`, `x64`, `x128` in that order).
 - Change "ASCIIbetical" sort to Unicode-aware "non-lowercase before lowercase".
diff --git a/src/doc/style-guide/src/expressions.md b/src/doc/style-guide/src/expressions.md
index 171a24cd89d..3bb0ee6d5ff 100644
--- a/src/doc/style-guide/src/expressions.md
+++ b/src/doc/style-guide/src/expressions.md
@@ -328,6 +328,37 @@ foo_bar
 Prefer line-breaking at an assignment operator (either `=` or `+=`, etc.) rather
 than at other binary operators.
 
+If line-breaking at a binary operator (including assignment operators) where the
+first operand spans multiple lines, use the base indentation of the *last*
+line of the first operand, and indent relative to that:
+
+```rust
+impl SomeType {
+    fn method(&mut self) {
+        self.array[array_index as usize]
+            .as_mut()
+            .expect("thing must exist")
+            .extra_info =
+                long_long_long_long_long_long_long_long_long_long_long_long_long_long_long;
+
+        self.array[array_index as usize]
+            .as_mut()
+            .expect("thing must exist")
+            .extra_info
+                + long_long_long_long_long_long_long_long_long_long_long_long_long_long_long;
+
+        self.array[array_index as usize]
+            .as_mut()
+            .expect("thing must exist")
+            .extra_info = Some(ExtraInfo {
+                parent,
+                count: count as u16,
+                children: children.into_boxed_slice(),
+            });
+    }
+}
+```
+
 ### Casts (`as`)
 
 Format `as` casts like a binary operator. In particular, always include spaces