bql: add prelude

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/bql/meson.build

@@ -31,6 +31,7 @@ _bql_rs = static_library(
       'src/lib.rs',
       'src/bindings.rs',
       'src/cell.rs',
+      'src/prelude.rs',
     ],
     {'.': _bql_bindings_inc_rs}
   ),

rust/bql/src/lib.rs

@@ -6,6 +6,11 @@ use bindings::{bql_block_unlock, bql_locked, rust_bql_mock_lock};
 mod cell;
 pub use cell::*;
 
+// preserve one-item-per-"use" syntax, it is clearer
+// for prelude-like modules
+#[rustfmt::skip]
+pub mod prelude;
+
 /// An internal function that is used by doctests.
 pub fn start_test() {
     // SAFETY: integration tests are run with --test-threads=1, while

rust/bql/src/prelude.rs

@@ -0,0 +1,4 @@
+//! Essential types and traits intended for blanket imports.
+
+pub use crate::cell::BqlCell;
+pub use crate::cell::BqlRefCell;

rust/chardev/src/chardev.rs

@@ -18,7 +18,7 @@ use std::{
     slice,
 };
 
-use bql::{BqlRefCell, BqlRefMut};
+use bql::{prelude::*, BqlRefMut};
 use common::{callbacks::FnCall, errno, Opaque};
 use qom::prelude::*;
 

rust/hw/char/pl011/src/device.rs

@@ -4,7 +4,7 @@
 
 use std::{ffi::CStr, mem::size_of};
 
-use bql::BqlRefCell;
+use bql::prelude::*;
 use chardev::prelude::*;
 use common::prelude::*;
 use hwcore::{prelude::*, ClockEvent, IRQState};

rust/hw/core/tests/tests.rs

@@ -4,7 +4,7 @@
 
 use std::{ffi::CStr, ptr::addr_of};
 
-use bql::BqlCell;
+use bql::prelude::*;
 use hwcore::prelude::*;
 use migration::prelude::*;
 use qom::{prelude::*, ObjectImpl, ParentField};

rust/hw/timer/hpet/src/device.rs

@@ -10,7 +10,7 @@ use std::{
     slice::from_ref,
 };
 
-use bql::{BqlCell, BqlRefCell};
+use bql::prelude::*;
 use common::prelude::*;
 use hwcore::prelude::*;
 use migration::{self, prelude::*};

rust/migration/src/migratable.rs

@@ -9,7 +9,7 @@ use std::{
     sync::{Arc, Mutex},
 };
 
-use bql::{BqlCell, BqlRefCell};
+use bql::prelude::*;
 use common::Zeroable;
 
 use crate::{

rust/tests/tests/vmstate_tests.rs

@@ -9,7 +9,7 @@ use std::{
     slice,
 };
 
-use bql::BqlCell;
+use bql::prelude::*;
 use common::Opaque;
 use migration::{
     bindings::{