Auto merge of #125443 - nnethercote:rustfmt-use-decls, r=lcnr,cuviper,GuillaumeGomez

rustfmt `use` declarations

This PR implements https://github.com/rust-lang/compiler-team/issues/750, which changes how `use` declarations are formatted by adding these options to `rustfmt.toml`:
```
group_imports = "StdExternalCrate"
imports_granularity = "Module"
```

r? `@ghost`

3 files changed, 2 insertions, 7 deletions

diff --git a/library/core/src/alloc/global.rs b/library/core/src/alloc/global.rs
index cf25deacb57..a6f799c4a7d 100644
--- a/library/core/src/alloc/global.rs
+++ b/library/core/src/alloc/global.rs
@@ -1,6 +1,5 @@
 use crate::alloc::Layout;
-use crate::cmp;
-use crate::ptr;
+use crate::{cmp, ptr};
 
 /// A memory allocator that can be registered as the standard library’s default
 /// through the `#[global_allocator]` attribute.
diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index 431b07035c3..549a4bc6727 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs
@@ -4,11 +4,9 @@
 // collections, resulting in having to optimize down excess IR multiple times.
 // Your performance intuition is useless. Run perf.
 
-use crate::cmp;
 use crate::error::Error;
-use crate::fmt;
-use crate::mem;
 use crate::ptr::{Alignment, NonNull};
+use crate::{cmp, fmt, mem};
 
 // While this function is used in one place and its implementation
 // could be inlined, the previous attempts to do so made rustc
diff --git a/library/core/src/alloc/mod.rs b/library/core/src/alloc/mod.rs
index 1c8e6676544..aa841db045c 100644
--- a/library/core/src/alloc/mod.rs
+++ b/library/core/src/alloc/mod.rs
@@ -17,10 +17,8 @@ pub use self::layout::Layout;
 )]
 #[allow(deprecated, deprecated_in_future)]
 pub use self::layout::LayoutErr;
-
 #[stable(feature = "alloc_layout_error", since = "1.50.0")]
 pub use self::layout::LayoutError;
-
 use crate::error::Error;
 use crate::fmt;
 use crate::ptr::{self, NonNull};