Auto merge of #130379 - Zalathar:rollup-wpmcnql, r=Zalathar

Rollup of 6 pull requests

Successful merges:

 - #130042 (properly handle EOF in BufReader::peek)
 - #130061 (Add `NonNull` convenience methods to `Box` and `Vec`)
 - #130202 (set `download-ci-llvm = true` by default on "library" and "tools" profiles)
 - #130214 (MaybeUninit::zeroed: mention that padding is not zeroed)
 - #130353 (Make some lint doctests compatible with `--stage=0`)
 - #130370 (unstable-book: `trait_upcasting` example should not have `#![allow(incomplete_features)]`)

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

4 files changed, 9 insertions, 3 deletions

diff --git a/src/bootstrap/defaults/config.library.toml b/src/bootstrap/defaults/config.library.toml
index 087544397f5..5447565a4b0 100644
--- a/src/bootstrap/defaults/config.library.toml
+++ b/src/bootstrap/defaults/config.library.toml
@@ -13,4 +13,5 @@ lto = "off"
 
 [llvm]
 # Will download LLVM from CI if available on your platform.
-download-ci-llvm = "if-unchanged"
+# If you intend to modify `src/llvm-project`, use `"if-unchanged"` or `false` instead.
+download-ci-llvm = true
diff --git a/src/bootstrap/defaults/config.tools.toml b/src/bootstrap/defaults/config.tools.toml
index 75ad37ce335..efb56996bcd 100644
--- a/src/bootstrap/defaults/config.tools.toml
+++ b/src/bootstrap/defaults/config.tools.toml
@@ -17,4 +17,5 @@ compiler-docs = true
 
 [llvm]
 # Will download LLVM from CI if available on your platform.
-download-ci-llvm = "if-unchanged"
+# If you intend to modify `src/llvm-project`, use `"if-unchanged"` or `false` instead.
+download-ci-llvm = true
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index 99bcc6e0787..bedaa15ccb9 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -255,4 +255,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Warning,
         summary: "`download-ci-llvm = true` now checks if CI llvm is available and has become the default for the compiler profile",
     },
+    ChangeInfo {
+        change_id: 130202,
+        severity: ChangeSeverity::Info,
+        summary: "'tools' and 'library' profiles switched `download-ci-llvm` option from `if-unchanged` to `true`.",
+    },
 ];
diff --git a/src/doc/unstable-book/src/language-features/trait-upcasting.md b/src/doc/unstable-book/src/language-features/trait-upcasting.md
index 3697ae38f9d..a5f99cc86f2 100644
--- a/src/doc/unstable-book/src/language-features/trait-upcasting.md
+++ b/src/doc/unstable-book/src/language-features/trait-upcasting.md
@@ -12,7 +12,6 @@ so long as `Bar: Foo`.
 
 ```rust,edition2018
 #![feature(trait_upcasting)]
-#![allow(incomplete_features)]
 
 trait Foo {}