edition: Remove extern crate lines

In Rust 2018 edition, `extern crate` is no longer required for importing
from other crates. Instead of writing:

    extern crate dep;
    use dep::Thing;

we write:

    use dep::Thing;

In this approach, macros are imported individually from the declaring
crate rather than through #[macro_use]. Before:

    #[macro_use]
    extern crate sys_util;

After:

    use sys_util::{debug, error};

The only place that `extern crate` continues to be required is in
importing the compiler's proc_macro API into a procedural macro crate.
This will hopefully be fixed in a future Rust release.

    extern crate proc_macro;

TEST=cargo check
TEST=cargo check --all-features
TEST=cargo check --target aarch64-unknown-linux-gnu
TEST=local kokoro

Change-Id: I0b43768c0d81f2a250b1959fb97ba35cbac56293
Reviewed-on: https://chromium-review.googlesource.com/1565302
Commit-Ready: David Tolnay <dtolnay@chromium.org>
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Tolnay <dtolnay@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: David Tolnay <dtolnay@chromium.org>

60 files changed, 9 insertions, 331 deletions

diff --git a/aarch64/src/lib.rs b/aarch64/src/lib.rs
index 07fbff5..95e633f 100644
--- a/aarch64/src/lib.rs
+++ b/aarch64/src/lib.rs
@@ -2,19 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate arch;
-extern crate data_model;
-extern crate devices;
-extern crate io_jail;
-extern crate kernel_cmdline;
-extern crate kvm;
-extern crate kvm_sys;
-extern crate libc;
-extern crate remain;
-extern crate resources;
-extern crate sync;
-extern crate sys_util;
-
 use std::error::Error as StdError;
 use std::ffi::{CStr, CString};
 use std::fmt::{self, Display};
diff --git a/arch/src/lib.rs b/arch/src/lib.rs
index 1e55caf..01c16a0 100644
--- a/arch/src/lib.rs
+++ b/arch/src/lib.rs
@@ -4,16 +4,6 @@
 
 pub mod fdt;
 
-extern crate byteorder;
-extern crate devices;
-extern crate io_jail;
-extern crate kernel_cmdline;
-extern crate kvm;
-extern crate libc;
-extern crate resources;
-extern crate sync;
-extern crate sys_util;
-
 use std::collections::BTreeMap;
 use std::error::Error as StdError;
 use std::fmt::{self, Display};
diff --git a/assertions/src/lib.rs b/assertions/src/lib.rs
index 316e7d2..2e9d188 100644
--- a/assertions/src/lib.rs
+++ b/assertions/src/lib.rs
@@ -20,7 +20,6 @@ pub use crate::mechanism::*;
 /// # Example
 ///
 /// ```rust
-/// extern crate assertions;
 /// use assertions::const_assert;
 ///
 /// fn main() {
@@ -31,7 +30,6 @@ pub use crate::mechanism::*;
 /// # Example that fails to compile
 ///
 /// ```rust,compile_fail
-/// extern crate assertions;
 /// use assertions::const_assert;
 ///
 /// fn main() {
diff --git a/bit_field/bit_field_derive/bit_field_derive.rs b/bit_field/bit_field_derive/bit_field_derive.rs
index e7d26cd..e81f481 100644
--- a/bit_field/bit_field_derive/bit_field_derive.rs
+++ b/bit_field/bit_field_derive/bit_field_derive.rs
@@ -3,14 +3,8 @@
 // found in the LICENSE file.
 
 #![recursion_limit = "256"]
-extern crate proc_macro;
-extern crate proc_macro2;
-
-#[macro_use]
-extern crate quote;
 
-#[macro_use]
-extern crate syn;
+extern crate proc_macro;
 
 use proc_macro2::{Span, TokenStream};
 use quote::{quote, quote_spanned};
diff --git a/bit_field/src/lib.rs b/bit_field/src/lib.rs
index bd11c3c..1455430 100644
--- a/bit_field/src/lib.rs
+++ b/bit_field/src/lib.rs
@@ -28,8 +28,6 @@
 //! first three fields.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -88,8 +86,6 @@
 //! `B1` but with accessors that use `bool` rather than `u8`.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -105,8 +101,6 @@
 //! the width with `#[bits = N]`. This should be used to improve type safety.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -133,8 +127,6 @@
 //! any variant will result in an `Err(u64)`.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -159,8 +151,6 @@
 //! getter and setter are defined in terms of the given enum type.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -187,8 +177,6 @@
 //! a bitfield struct.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -215,8 +203,6 @@
 //! rewriting by the macro.
 //!
 //! ```
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -235,8 +221,6 @@
 //! > the trait `bit_field::checks::TotalSizeIsMultipleOfEightBits` is not implemented
 //!
 //! ```compile_fail
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -251,8 +235,6 @@
 //! (2^n)-1, it will be caught at compile time.
 //!
 //! ```compile_fail
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -268,8 +250,6 @@
 //! number of bits in that field, it will be caught.
 //!
 //! ```compile_fail
-//! extern crate bit_field;
-//!
 //! use bit_field::*;
 //!
 //! #[bitfield]
@@ -289,10 +269,6 @@
 
 use std::fmt::{self, Display};
 
-#[allow(unused_imports)]
-#[macro_use]
-extern crate bit_field_derive;
-
 pub use bit_field_derive::bitfield;
 
 /// Error type for bit field get.
diff --git a/bit_field/tests/test_enum.rs b/bit_field/tests/test_enum.rs
index 8746b06..3ce6edb 100644
--- a/bit_field/tests/test_enum.rs
+++ b/bit_field/tests/test_enum.rs
@@ -1,5 +1,3 @@
-extern crate bit_field;
-
 use bit_field::*;
 
 #[bitfield]
diff --git a/bit_field/tests/test_tuple_struct.rs b/bit_field/tests/test_tuple_struct.rs
index 3b12735..b92d99c 100644
--- a/bit_field/tests/test_tuple_struct.rs
+++ b/bit_field/tests/test_tuple_struct.rs
@@ -1,5 +1,3 @@
-extern crate bit_field;
-
 use bit_field::*;
 
 #[bitfield]
diff --git a/crosvm_plugin/src/lib.rs b/crosvm_plugin/src/lib.rs
index 8b0a222..5c1f168 100644
--- a/crosvm_plugin/src/lib.rs
+++ b/crosvm_plugin/src/lib.rs
@@ -15,13 +15,6 @@
 //! connection's socket. Then, that socket is read for a `MainResponse` or `VcpuResponse`, which is
 //! translated to the appropriate return type for the C API.
 
-extern crate kvm;
-extern crate kvm_sys;
-extern crate libc;
-extern crate protobuf;
-extern crate protos;
-extern crate sys_util;
-
 use std::env;
 use std::fs::File;
 use std::mem::{size_of, swap};
diff --git a/data_model/src/lib.rs b/data_model/src/lib.rs
index d3f3517..7d3fd46 100644
--- a/data_model/src/lib.rs
+++ b/data_model/src/lib.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate assertions;
-
 use std::mem::size_of;
 use std::slice::{from_raw_parts, from_raw_parts_mut};
 
diff --git a/devices/src/lib.rs b/devices/src/lib.rs
index d28ea15..3b2c0b2 100644
--- a/devices/src/lib.rs
+++ b/devices/src/lib.rs
@@ -4,31 +4,6 @@
 
 //! Emulates virtual and hardware devices.
 
-extern crate audio_streams;
-extern crate bit_field;
-extern crate byteorder;
-extern crate data_model;
-extern crate enumn;
-extern crate io_jail;
-extern crate kvm;
-extern crate libc;
-extern crate msg_on_socket_derive;
-extern crate msg_socket;
-extern crate net_sys;
-extern crate net_util;
-extern crate p9;
-extern crate remain;
-extern crate resources;
-extern crate sync;
-#[macro_use]
-extern crate sys_util;
-#[cfg(feature = "tpm")]
-extern crate tpm2;
-extern crate usb_util;
-extern crate vhost;
-extern crate virtio_sys;
-extern crate vm_control;
-
 mod bus;
 mod cmos;
 mod i8042;
diff --git a/devices/src/usb/mod.rs b/devices/src/usb/mod.rs
index 738c693..dde6189 100644
--- a/devices/src/usb/mod.rs
+++ b/devices/src/usb/mod.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate usb_util;
-
 #[macro_use]
 mod log;
 pub mod host_backend;
diff --git a/devices/src/virtio/gpu/mod.rs b/devices/src/virtio/gpu/mod.rs
index a91b5b9..251b59c 100644
--- a/devices/src/virtio/gpu/mod.rs
+++ b/devices/src/virtio/gpu/mod.rs
@@ -2,10 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate gpu_buffer;
-extern crate gpu_display;
-extern crate gpu_renderer;
-
 mod backend;
 mod protocol;
 
diff --git a/enumn/src/lib.rs b/enumn/src/lib.rs
index 417ba96..416eadc 100644
--- a/enumn/src/lib.rs
+++ b/enumn/src/lib.rs
@@ -104,9 +104,6 @@
 #![recursion_limit = "128"]
 
 extern crate proc_macro;
-extern crate proc_macro2;
-extern crate quote;
-extern crate syn;
 
 #[cfg(test)]
 mod tests;
diff --git a/fuzz/block_fuzzer.rs b/fuzz/block_fuzzer.rs
index 5c3106a..f315a87 100644
--- a/fuzz/block_fuzzer.rs
+++ b/fuzz/block_fuzzer.rs
@@ -3,11 +3,6 @@
 // found in the LICENSE file.
 
 #![no_main]
-extern crate devices;
-extern crate libc;
-extern crate sys_util;
-
-use sys_util::{EventFd, GuestAddress, GuestMemory, SharedMemory};
 
 use std::fs::File;
 use std::io::{Cursor, Read, Seek, SeekFrom};
@@ -20,6 +15,7 @@ use std::sync::atomic::AtomicUsize;
 use std::sync::Arc;
 
 use devices::virtio::{Block, Queue, VirtioDevice};
+use sys_util::{EventFd, GuestAddress, GuestMemory, SharedMemory};
 
 const MEM_SIZE: u64 = 256 * 1024 * 1024;
 const DESC_SIZE: u64 = 16; // Bytes in one virtio descriptor.
diff --git a/fuzz/qcow_fuzzer.rs b/fuzz/qcow_fuzzer.rs
index 0f7ff2a..e6175ff 100644
--- a/fuzz/qcow_fuzzer.rs
+++ b/fuzz/qcow_fuzzer.rs
@@ -3,9 +3,6 @@
 // found in the LICENSE file.
 
 #![no_main]
-extern crate libc;
-extern crate qcow;
-extern crate sys_util;
 
 use qcow::QcowFile;
 use sys_util::SharedMemory;
diff --git a/fuzz/zimage_fuzzer.rs b/fuzz/zimage_fuzzer.rs
index 13b67b3..fdcb7db 100644
--- a/fuzz/zimage_fuzzer.rs
+++ b/fuzz/zimage_fuzzer.rs
@@ -3,9 +3,6 @@
 // found in the LICENSE file.
 
 #![no_main]
-extern crate kernel_loader;
-extern crate libc;
-extern crate sys_util;
 
 use sys_util::{GuestAddress, GuestMemory};
 
diff --git a/gpu_buffer/src/lib.rs b/gpu_buffer/src/lib.rs
index b69afc7..f35f5fd 100644
--- a/gpu_buffer/src/lib.rs
+++ b/gpu_buffer/src/lib.rs
@@ -30,10 +30,6 @@
 //! # }
 //! ```
 
-extern crate data_model;
-#[macro_use]
-extern crate sys_util;
-
 mod drm_formats;
 mod raw;
 pub mod rendernode;
diff --git a/gpu_display/build.rs b/gpu_display/build.rs
index 33a8653..69c0fae 100644
--- a/gpu_display/build.rs
+++ b/gpu_display/build.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate cc;
-
 use std::env;
 use std::ffi::OsStr;
 use std::fs;
diff --git a/gpu_display/examples/simple.rs b/gpu_display/examples/simple.rs
index e3499f8..fcf2e54 100644
--- a/gpu_display/examples/simple.rs
+++ b/gpu_display/examples/simple.rs
@@ -1,5 +1,3 @@
-extern crate gpu_display;
-
 use gpu_display::*;
 
 fn main() {
diff --git a/gpu_display/src/lib.rs b/gpu_display/src/lib.rs
index c52e5e9..11a6703 100644
--- a/gpu_display/src/lib.rs
+++ b/gpu_display/src/lib.rs
@@ -4,9 +4,6 @@
 
 //! Crate for displaying simple surfaces and GPU buffers over wayland.
 
-extern crate data_model;
-extern crate sys_util;
-
 mod dwl;
 
 use std::cell::Cell;
diff --git a/gpu_renderer/src/lib.rs b/gpu_renderer/src/lib.rs
index 1852f0a..b4abfca 100644
--- a/gpu_renderer/src/lib.rs
+++ b/gpu_renderer/src/lib.rs
@@ -4,10 +4,6 @@
 
 //! A crate for using hardware acceleration to render virtio-gpu's virgl command streams.
 
-extern crate data_model;
-extern crate libc;
-extern crate sys_util;
-
 mod command_buffer;
 mod generated;
 mod pipe_format_fourcc;
diff --git a/io_jail/src/lib.rs b/io_jail/src/lib.rs
index 26f96d7..43698aa 100644
--- a/io_jail/src/lib.rs
+++ b/io_jail/src/lib.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate libc;
-
 #[allow(dead_code)]
 #[allow(non_camel_case_types)]
 #[allow(non_snake_case)]
diff --git a/io_jail/src/libminijail.rs b/io_jail/src/libminijail.rs
index 6edacdc..f8c3654 100644
--- a/io_jail/src/libminijail.rs
+++ b/io_jail/src/libminijail.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate libc;
-
 use libc::{gid_t, pid_t, uid_t};
 use std::os::raw::{c_char, c_int, c_ulong};
 
diff --git a/kernel_loader/src/lib.rs b/kernel_loader/src/lib.rs
index 15693a6..66a8dfb 100644
--- a/kernel_loader/src/lib.rs
+++ b/kernel_loader/src/lib.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate sys_util;
-
 use std::ffi::CStr;
 use std::fmt::{self, Display};
 use std::io::{Read, Seek, SeekFrom};
diff --git a/kvm/src/lib.rs b/kvm/src/lib.rs
index 67a2f23..919aad3 100644
--- a/kvm/src/lib.rs
+++ b/kvm/src/lib.rs
@@ -4,12 +4,6 @@
 
 //! A safe wrapper around the kernel's KVM interface.
 
-extern crate kvm_sys;
-extern crate libc;
-#[macro_use]
-extern crate sys_util;
-extern crate msg_socket;
-
 mod cap;
 
 use std::cmp::{min, Ordering};
diff --git a/kvm/tests/dirty_log.rs b/kvm/tests/dirty_log.rs
index 645a01d..4efb208 100644
--- a/kvm/tests/dirty_log.rs
+++ b/kvm/tests/dirty_log.rs
@@ -4,10 +4,6 @@
 
 #![cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 
-extern crate kvm;
-extern crate kvm_sys;
-extern crate sys_util;
-
 use kvm::*;
 use kvm_sys::kvm_regs;
 use sys_util::{GuestAddress, GuestMemory, MemoryMapping, SharedMemory};
diff --git a/kvm/tests/read_only_memory.rs b/kvm/tests/read_only_memory.rs
index 5114ce4..c1dd854 100644
--- a/kvm/tests/read_only_memory.rs
+++ b/kvm/tests/read_only_memory.rs
@@ -4,10 +4,6 @@
 
 #![cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 
-extern crate kvm;
-extern crate kvm_sys;
-extern crate sys_util;
-
 use kvm::*;
 use kvm_sys::kvm_regs;
 use sys_util::{GuestAddress, GuestMemory, MemoryMapping, SharedMemory};
diff --git a/kvm/tests/real_run_adder.rs b/kvm/tests/real_run_adder.rs
index 5a7b536..a419ad9 100644
--- a/kvm/tests/real_run_adder.rs
+++ b/kvm/tests/real_run_adder.rs
@@ -4,10 +4,6 @@
 
 #![cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 
-extern crate kvm;
-extern crate kvm_sys;
-extern crate sys_util;
-
 use kvm::*;
 use kvm_sys::kvm_regs;
 use sys_util::{GuestAddress, GuestMemory};
diff --git a/kvm_sys/src/lib.rs b/kvm_sys/src/lib.rs
index bea9242..9000b79 100644
--- a/kvm_sys/src/lib.rs
+++ b/kvm_sys/src/lib.rs
@@ -6,9 +6,6 @@
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
 
-#[macro_use]
-extern crate sys_util;
-
 use sys_util::{ioctl_io_nr, ioctl_ior_nr, ioctl_iow_nr, ioctl_iowr_nr};
 
 // Somehow this one gets missed by bindgen
diff --git a/kvm_sys/tests/sanity.rs b/kvm_sys/tests/sanity.rs
index 2dd1326..7669b44 100644
--- a/kvm_sys/tests/sanity.rs
+++ b/kvm_sys/tests/sanity.rs
@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate kvm_sys;
-extern crate libc;
-
 use libc::{c_char, ioctl, open, O_RDWR};
 
 use kvm_sys::*;
diff --git a/msg_socket/msg_on_socket_derive/msg_on_socket_derive.rs b/msg_socket/msg_on_socket_derive/msg_on_socket_derive.rs
index bb90255..5116d7e 100644
--- a/msg_socket/msg_on_socket_derive/msg_on_socket_derive.rs
+++ b/msg_socket/msg_on_socket_derive/msg_on_socket_derive.rs
@@ -4,13 +4,6 @@
 
 #![recursion_limit = "256"]
 extern crate proc_macro;
-extern crate proc_macro2;
-
-#[macro_use]
-extern crate quote;
-
-#[macro_use]
-extern crate syn;
 
 use std::vec::Vec;
 
diff --git a/msg_socket/src/lib.rs b/msg_socket/src/lib.rs
index c3cc411..bead3da 100644
--- a/msg_socket/src/lib.rs
+++ b/msg_socket/src/lib.rs
@@ -2,13 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#[allow(unused_imports)]
-#[macro_use]
-extern crate msg_on_socket_derive;
-extern crate data_model;
-#[macro_use]
-extern crate sys_util;
-
 mod msg_on_socket;
 
 use std::io::Result;
diff --git a/msg_socket/tests/enum.rs b/msg_socket/tests/enum.rs
index 9134f6e..b4c7189 100644
--- a/msg_socket/tests/enum.rs
+++ b/msg_socket/tests/enum.rs
@@ -1,7 +1,3 @@
-extern crate msg_on_socket_derive;
-extern crate msg_socket;
-extern crate sys_util;
-
 use sys_util::EventFd;
 
 use msg_socket::*;
diff --git a/msg_socket/tests/struct.rs b/msg_socket/tests/struct.rs
index a2d5c9c..2cc9d37 100644
--- a/msg_socket/tests/struct.rs
+++ b/msg_socket/tests/struct.rs
@@ -1,7 +1,3 @@
-extern crate msg_on_socket_derive;
-extern crate msg_socket;
-extern crate sys_util;
-
 use sys_util::EventFd;
 
 use msg_socket::*;
diff --git a/msg_socket/tests/tuple.rs b/msg_socket/tests/tuple.rs
index 717cd91..b388328 100644
--- a/msg_socket/tests/tuple.rs
+++ b/msg_socket/tests/tuple.rs
@@ -1,10 +1,5 @@
-extern crate msg_on_socket_derive;
-extern crate msg_socket;
-extern crate sys_util;
-
-use sys_util::EventFd;
-
 use msg_socket::*;
+use sys_util::EventFd;
 
 #[derive(MsgOnSocket)]
 struct Message(u8, u16, EventFd);
diff --git a/net_sys/src/lib.rs b/net_sys/src/lib.rs
index 4be0a16..9df49e4 100644
--- a/net_sys/src/lib.rs
+++ b/net_sys/src/lib.rs
@@ -6,9 +6,6 @@
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
 
-#[macro_use]
-extern crate sys_util;
-
 use sys_util::{ioctl_ior_nr, ioctl_iow_nr};
 
 // generated with bindgen /usr/include/linux/if.h --no-unstable-rust
diff --git a/net_util/src/lib.rs b/net_util/src/lib.rs
index 456608c..0a903fc 100644
--- a/net_util/src/lib.rs
+++ b/net_util/src/lib.rs
@@ -2,10 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate libc;
-extern crate net_sys;
-extern crate sys_util;
-
 use std::fmt::{self, Display};
 use std::fs::File;
 use std::io::{Read, Result as IoResult, Write};
diff --git a/p9/src/lib.rs b/p9/src/lib.rs
index 9bd8c05..56195f1 100644
--- a/p9/src/lib.rs
+++ b/p9/src/lib.rs
@@ -2,11 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate libc;
-
-#[macro_use]
-extern crate wire_format_derive;
-
 mod protocol;
 mod server;
 
diff --git a/p9/wire_format_derive/wire_format_derive.rs b/p9/wire_format_derive/wire_format_derive.rs
index 38af595..ea19b89 100644
--- a/p9/wire_format_derive/wire_format_derive.rs
+++ b/p9/wire_format_derive/wire_format_derive.rs
@@ -9,13 +9,6 @@
 #![recursion_limit = "256"]
 
 extern crate proc_macro;
-extern crate proc_macro2;
-
-#[macro_use]
-extern crate quote;
-
-#[macro_use]
-extern crate syn;
 
 use proc_macro2::{Span, TokenStream};
 use quote::{quote, quote_spanned};
@@ -46,9 +39,8 @@ fn p9_wire_format_inner(input: DeriveInput) -> TokenStream {
     let scope = Ident::new(&scope, Span::call_site());
     quote! {
         mod #scope {
-            extern crate std;
-            use self::std::io;
-            use self::std::result::Result::Ok;
+            use std::io;
+            use std::result::Result::Ok;
 
             use super::#container;
 
@@ -245,9 +237,8 @@ mod tests {
 
         let expected = quote! {
             mod wire_format_niijima_先輩 {
-                extern crate std;
-                use self::std::io;
-                use self::std::result::Result::Ok;
+                use std::io;
+                use std::result::Result::Ok;
 
                 use super::Niijima_先輩;
 
diff --git a/qcow/src/qcow.rs b/qcow/src/qcow.rs
index 9015bb1..52a6cc2 100644
--- a/qcow/src/qcow.rs
+++ b/qcow/src/qcow.rs
@@ -2,12 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate byteorder;
-extern crate libc;
-extern crate remain;
-#[macro_use]
-extern crate sys_util;
-
 mod qcow_raw_file;
 mod refcount;
 mod vec_cache;
diff --git a/qcow_utils/src/qcow_img.rs b/qcow_utils/src/qcow_img.rs
index 4f8be58..66230da 100644
--- a/qcow_utils/src/qcow_img.rs
+++ b/qcow_utils/src/qcow_img.rs
@@ -2,10 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate getopts;
-extern crate qcow;
-extern crate sys_util;
-
 use std::fs::OpenOptions;
 use std::io::{Read, Write};
 
diff --git a/qcow_utils/src/qcow_utils.rs b/qcow_utils/src/qcow_utils.rs
index 534d886..6c8b86f 100644
--- a/qcow_utils/src/qcow_utils.rs
+++ b/qcow_utils/src/qcow_utils.rs
@@ -4,10 +4,6 @@
 
 // Exported interface to basic qcow functionality to be used from C.
 
-extern crate libc;
-extern crate qcow;
-extern crate sys_util;
-
 use libc::{EBADFD, EINVAL, EIO, ENOSYS};
 use std::ffi::CStr;
 use std::fs::{File, OpenOptions};
diff --git a/render_node_forward/Cargo.toml b/render_node_forward/Cargo.toml
index accd36d..d23b46a 100644
--- a/render_node_forward/Cargo.toml
+++ b/render_node_forward/Cargo.toml
@@ -2,6 +2,7 @@
 name = "render_node_forward"
 version = "0.1.0"
 authors = ["The Chromium OS Authors"]
+edition = "2018"
 
 [lib]
 path = "lib.rs"
diff --git a/render_node_forward/lib.rs b/render_node_forward/lib.rs
index 8c04eb9..f96fdd1 100644
--- a/render_node_forward/lib.rs
+++ b/render_node_forward/lib.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate sys_util;
-
 use sys_util::{GuestAddress, GuestMemory, MemoryMapping};
 
 #[link(name = "rendernodehost")]
diff --git a/resources/src/lib.rs b/resources/src/lib.rs
index f300e0e..602c390 100644
--- a/resources/src/lib.rs
+++ b/resources/src/lib.rs
@@ -4,12 +4,6 @@
 
 //! Manages system resources that can be allocated to VMs and their devices.
 
-#[cfg(feature = "wl-dmabuf")]
-extern crate gpu_buffer;
-extern crate libc;
-extern crate msg_socket;
-extern crate sys_util;
-
 mod address_allocator;
 mod gpu_allocator;
 mod system_allocator;
diff --git a/src/linux.rs b/src/linux.rs
index 730de9c..fcfcf94 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -60,9 +60,7 @@ use aarch64::AArch64 as Arch;
 use x86_64::X8664arch as Arch;
 
 #[cfg(feature = "gpu-forward")]
-extern crate render_node_forward;
-#[cfg(feature = "gpu-forward")]
-use self::render_node_forward::*;
+use render_node_forward::*;
 #[cfg(not(feature = "gpu-forward"))]
 type RenderNodeHost = ();
 
diff --git a/src/main.rs b/src/main.rs
index b1d2cb2..c8cb2ea 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -4,40 +4,6 @@
 
 //! Runs a virtual machine under KVM
 
-#[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
-extern crate aarch64;
-extern crate arch;
-extern crate audio_streams;
-extern crate byteorder;
-extern crate devices;
-extern crate io_jail;
-extern crate kernel_cmdline;
-extern crate kernel_loader;
-extern crate kvm;
-extern crate kvm_sys;
-extern crate libc;
-extern crate libcras;
-extern crate net_util;
-extern crate qcow;
-#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
-extern crate x86_64;
-#[macro_use]
-extern crate sys_util;
-extern crate data_model;
-#[cfg(feature = "wl-dmabuf")]
-extern crate gpu_buffer;
-extern crate msg_socket;
-#[cfg(feature = "plugin")]
-extern crate protobuf;
-#[cfg(feature = "plugin")]
-extern crate protos;
-extern crate rand_ish;
-extern crate remain;
-extern crate resources;
-extern crate sync;
-extern crate vhost;
-extern crate vm_control;
-
 pub mod argument;
 pub mod linux;
 pub mod panic_hook;
diff --git a/sys_util/poll_token_derive/poll_token_derive.rs b/sys_util/poll_token_derive/poll_token_derive.rs
index 582016b..7b7baac 100644
--- a/sys_util/poll_token_derive/poll_token_derive.rs
+++ b/sys_util/poll_token_derive/poll_token_derive.rs
@@ -5,9 +5,6 @@
 #![recursion_limit = "128"]
 
 extern crate proc_macro;
-extern crate proc_macro2;
-extern crate quote;
-extern crate syn;
 
 use proc_macro2::{Ident, TokenStream};
 use quote::quote;
diff --git a/sys_util/src/capabilities.rs b/sys_util/src/capabilities.rs
index 5f42ab8..90b8784 100644
--- a/sys_util/src/capabilities.rs
+++ b/sys_util/src/capabilities.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate libc;
-
 use libc::{c_int, c_void};
 
 use crate::{errno_result, Result};
diff --git a/sys_util/src/lib.rs b/sys_util/src/lib.rs
index d62ec48..a1dffea 100644
--- a/sys_util/src/lib.rs
+++ b/sys_util/src/lib.rs
@@ -4,14 +4,6 @@
 
 //! Small system utility modules for usage by other modules.
 
-extern crate data_model;
-extern crate libc;
-extern crate syscall_defines;
-#[allow(unused_imports)]
-#[macro_use]
-extern crate poll_token_derive;
-extern crate sync;
-
 pub mod affinity;
 #[macro_use]
 pub mod handle_eintr;
@@ -226,8 +218,6 @@ pub fn fallocate(
 /// Reaps all child processes until there are no terminated children to reap.
 ///
 /// ```
-/// # extern crate libc;
-/// # extern crate sys_util;
 /// fn reap_children() {
 ///     loop {
 ///         match sys_util::reap_child() {
diff --git a/tempfile/src/lib.rs b/tempfile/src/lib.rs
index c04f0f7..14f235b 100644
--- a/tempfile/src/lib.rs
+++ b/tempfile/src/lib.rs
@@ -5,8 +5,6 @@
 //! Simplified tempfile which doesn't depend on the `rand` crate, instead using
 //! /dev/urandom as a source of entropy
 
-extern crate rand_ish;
-
 use rand_ish::urandom_str;
 use std::env;
 use std::fs;
diff --git a/tests/plugins.rs b/tests/plugins.rs
index e95cc07..b00309f 100644
--- a/tests/plugins.rs
+++ b/tests/plugins.rs
@@ -4,9 +4,6 @@
 
 #![cfg(feature = "plugin")]
 
-extern crate rand_ish;
-extern crate sys_util;
-
 use std::env::{current_exe, var_os};
 use std::ffi::OsString;
 use std::fs::{remove_file, File};
diff --git a/usb_util/build.rs b/usb_util/build.rs
index ee6ab30..34e14da 100644
--- a/usb_util/build.rs
+++ b/usb_util/build.rs
@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate pkg_config;
 use std::env;
 
 fn main() {
diff --git a/usb_util/src/lib.rs b/usb_util/src/lib.rs
index 39e098a..8755428 100644
--- a/usb_util/src/lib.rs
+++ b/usb_util/src/lib.rs
@@ -10,10 +10,6 @@
 #[cfg_attr(feature = "cargo-clippy", allow(clippy))]
 mod bindings;
 
-extern crate assertions;
-extern crate data_model;
-extern crate sync;
-
 #[macro_use]
 pub mod error;
 pub mod config_descriptor;
diff --git a/vhost/src/lib.rs b/vhost/src/lib.rs
index e841294..917e1dc 100644
--- a/vhost/src/lib.rs
+++ b/vhost/src/lib.rs
@@ -2,11 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate libc;
-extern crate net_util;
-extern crate sys_util;
-extern crate virtio_sys;
-
 pub mod net;
 mod vsock;
 
diff --git a/virtio_sys/src/lib.rs b/virtio_sys/src/lib.rs
index eb74225..680d133 100644
--- a/virtio_sys/src/lib.rs
+++ b/virtio_sys/src/lib.rs
@@ -6,9 +6,6 @@
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
 
-#[macro_use]
-extern crate sys_util;
-
 use sys_util::{ioctl_io_nr, ioctl_ior_nr, ioctl_iow_nr, ioctl_iowr_nr};
 
 // generated with bindgen /usr/include/linux/vhost.h --no-unstable-rust --constified-enum '*' --with-derive-default
diff --git a/vm_control/src/lib.rs b/vm_control/src/lib.rs
index 79d95ed..ac974a1 100644
--- a/vm_control/src/lib.rs
+++ b/vm_control/src/lib.rs
@@ -10,14 +10,6 @@
 //! The wire message format is a little-endian C-struct of fixed size, along with a file descriptor
 //! if the request type expects one.
 
-extern crate byteorder;
-extern crate kvm;
-extern crate libc;
-extern crate msg_socket;
-extern crate resources;
-#[macro_use]
-extern crate sys_util;
-
 use std::fmt::{self, Display};
 use std::fs::File;
 use std::io::{Seek, SeekFrom};
diff --git a/x86_64/build.rs b/x86_64/build.rs
index 77f3ae4..5f2c1eb 100644
--- a/x86_64/build.rs
+++ b/x86_64/build.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate cc;
-
 fn main() {
     cc::Build::new().file("host_cpuid.c").compile("host_cpuid");
 }
diff --git a/x86_64/src/fdt.rs b/x86_64/src/fdt.rs
index 8fc81ea..b072b9e 100644
--- a/x86_64/src/fdt.rs
+++ b/x86_64/src/fdt.rs
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate arch;
-
 use arch::fdt::{begin_node, end_node, finish_fdt, property_string, start_fdt, Error};
 use std::fs::File;
 use std::io::BufRead;
diff --git a/x86_64/src/lib.rs b/x86_64/src/lib.rs
index 3272086..997ed40 100644
--- a/x86_64/src/lib.rs
+++ b/x86_64/src/lib.rs
@@ -2,21 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern crate arch;
-extern crate byteorder;
-extern crate data_model;
-extern crate devices;
-extern crate io_jail;
-extern crate kernel_cmdline;
-extern crate kernel_loader;
-extern crate kvm;
-extern crate kvm_sys;
-extern crate libc;
-extern crate remain;
-extern crate resources;
-extern crate sync;
-extern crate sys_util;
-
 mod fdt;
 
 const X86_64_FDT_MAX_SIZE: u64 = 0x200000;