fmt: Use vertical import formatting within libc

The crate has a lot of reexports and will be getting many more. Change
the formatting to vertical to reduce the possibility of conflicts.

(backport <#4772>)
(cherry picked from commit c04afc0)

Author: tgross35

ci/style.sh

@@ -40,7 +40,7 @@ while IFS= read -r file; do
     # Format the file. We need to invoke `rustfmt` directly since `cargo fmt`
     # can't figure out the module tree with the hacks in place.
     failed=false
-    rustfmt --config-path rustfmt.toml "$file" ${check:+"$check"} || failed=true
+    rustfmt "$file" ${check:+"$check"} || failed=true
 
     # Restore all changes to the files.
     perl -pi -e 's/fn (\w+)_fmt_tmp\(\)/$1!/g' "$file"

rustfmt.toml

@@ -1,3 +1,4 @@
+# Note that there is a separate configuration for `src/`
 edition = "2021"
 error_on_line_overflow = true
 group_imports = "StdExternalCrate"

src/macros.rs

@@ -76,26 +76,59 @@ macro_rules! prelude {
             #[allow(unused_imports)]
             pub(crate) use core::default::Default;
             #[allow(unused_imports)]
-            pub(crate) use core::marker::{Copy, Send, Sync};
+            pub(crate) use core::marker::{
+                Copy,
+                Send,
+                Sync,
+            };
             #[allow(unused_imports)]
             pub(crate) use core::option::Option;
             #[allow(unused_imports)]
             pub(crate) use core::prelude::v1::derive;
             #[allow(unused_imports)]
-            pub(crate) use core::{fmt, hash, iter, mem, ptr};
+            pub(crate) use core::{
+                fmt,
+                hash,
+                iter,
+                mem,
+                ptr,
+            };
 
             #[allow(unused_imports)]
             pub(crate) use fmt::Debug;
             #[allow(unused_imports)]
-            pub(crate) use mem::{align_of, align_of_val, size_of, size_of_val};
+            pub(crate) use mem::{
+                align_of,
+                align_of_val,
+                size_of,
+                size_of_val,
+            };
 
             #[allow(unused_imports)]
-            pub(crate) use crate::types::{CEnumRepr, Padding};
+            pub(crate) use crate::types::{
+                CEnumRepr,
+                Padding,
+            };
             // Commonly used types defined in this crate
             #[allow(unused_imports)]
             pub(crate) use crate::{
-                c_char, c_double, c_float, c_int, c_long, c_longlong, c_short, c_uchar, c_uint,
-                c_ulong, c_ulonglong, c_ushort, c_void, intptr_t, size_t, ssize_t, uintptr_t,
+                c_char,
+                c_double,
+                c_float,
+                c_int,
+                c_long,
+                c_longlong,
+                c_short,
+                c_uchar,
+                c_uint,
+                c_ulong,
+                c_ulonglong,
+                c_ushort,
+                c_void,
+                intptr_t,
+                size_t,
+                ssize_t,
+                uintptr_t,
             };
         }
     };

src/rustfmt.toml

@@ -0,0 +1,7 @@
+# Note that there is a separate top-level configuration for everything else
+edition = "2021"
+error_on_line_overflow = true
+group_imports = "StdExternalCrate"
+imports_granularity = "Module"
+# This crate gets large lists of reexports. Use vertical to reduce conflicts.
+imports_layout = "Vertical"

src/unix/aix/mod.rs

@@ -1,5 +1,8 @@
 use crate::prelude::*;
-use crate::{in_addr_t, in_port_t};
+use crate::{
+    in_addr_t,
+    in_port_t,
+};
 
 pub type caddr_t = *mut c_char;
 pub type clockid_t = c_longlong;

src/unix/bsd/apple/mod.rs

@@ -3,7 +3,10 @@
 //! This covers *-apple-* triples currently
 
 use crate::prelude::*;
-use crate::{cmsghdr, off_t};
+use crate::{
+    cmsghdr,
+    off_t,
+};
 
 pub type wchar_t = i32;
 pub type clock_t = c_ulong;

src/unix/bsd/freebsdlike/dragonfly/mod.rs

@@ -1,5 +1,8 @@
 use crate::prelude::*;
-use crate::{cmsghdr, off_t};
+use crate::{
+    cmsghdr,
+    off_t,
+};
 
 pub type dev_t = u32;
 pub type wchar_t = i32;

src/unix/bsd/freebsdlike/freebsd/mod.rs

@@ -1,5 +1,8 @@
 use crate::prelude::*;
-use crate::{cmsghdr, off_t};
+use crate::{
+    cmsghdr,
+    off_t,
+};
 
 pub type fflags_t = u32;
 

src/unix/bsd/netbsdlike/netbsd/mod.rs

@@ -1,5 +1,8 @@
 use crate::prelude::*;
-use crate::{cmsghdr, off_t};
+use crate::{
+    cmsghdr,
+    off_t,
+};
 
 pub type clock_t = c_uint;
 pub type suseconds_t = c_int;

src/unix/bsd/netbsdlike/openbsd/mod.rs

@@ -1,6 +1,9 @@
 use crate::prelude::*;
 use crate::unix::bsd::O_SYNC;
-use crate::{cmsghdr, off_t};
+use crate::{
+    cmsghdr,
+    off_t,
+};
 
 pub type clock_t = i64;
 pub type suseconds_t = c_long;