rust: replace c_str! with c"" literals

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/devel/rust.rst

@@ -81,9 +81,6 @@ are missing:
 * "Return position ``impl Trait`` in Traits" (1.75.0, blocker for including
   the pinned-init create).
 
-* ``c"" literals`` (stable in 1.77.0).  QEMU provides a ``c_str!()`` macro
-  to define ``CStr`` constants easily
-
 * inline const expression (stable in 1.79.0), currently worked around with
   associated constants in the ``FnCall`` trait.
 
@@ -166,7 +163,6 @@ module           status
 ``bitops``       complete
 ``callbacks``    complete
 ``cell``         stable
-``c_str``        complete
 ``errno``        complete
 ``irq``          complete
 ``memory``       stable
@@ -423,7 +419,7 @@ Adding dependencies
 Generally, the set of dependent crates is kept small.  Think twice before
 adding a new external crate, especially if it comes with a large set of
 dependencies itself.  Sometimes QEMU only needs a small subset of the
-functionality; see for example QEMU's ``assertions`` or ``c_str`` modules.
+functionality; see for example QEMU's ``assertions`` module.
 
 On top of this recommendation, adding external crates to QEMU is a
 slightly complicated process, mostly due to the need to teach Meson how

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

@@ -9,7 +9,6 @@ use std::{
 
 use qemu_api::{
     bindings::{qdev_prop_bool, qdev_prop_chr},
-    c_str,
     prelude::*,
     vmstate::VMStateDescription,
     vmstate_clock, vmstate_fields, vmstate_of, vmstate_struct, vmstate_subsections, vmstate_unused,
@@ -25,7 +24,7 @@ extern "C" fn pl011_clock_needed(opaque: *mut c_void) -> bool {
 
 /// Migration subsection for [`PL011State`] clock.
 static VMSTATE_PL011_CLOCK: VMStateDescription = VMStateDescription {
-    name: c_str!("pl011/clock").as_ptr(),
+    name: c"pl011/clock".as_ptr(),
     version_id: 1,
     minimum_version_id: 1,
     needed: Some(pl011_clock_needed),
@@ -46,7 +45,7 @@ extern "C" fn pl011_post_load(opaque: *mut c_void, version_id: c_int) -> c_int {
 }
 
 static VMSTATE_PL011_REGS: VMStateDescription = VMStateDescription {
-    name: c_str!("pl011/regs").as_ptr(),
+    name: c"pl011/regs".as_ptr(),
     version_id: 2,
     minimum_version_id: 2,
     fields: vmstate_fields! {
@@ -70,7 +69,7 @@ static VMSTATE_PL011_REGS: VMStateDescription = VMStateDescription {
 };
 
 pub static VMSTATE_PL011: VMStateDescription = VMStateDescription {
-    name: c_str!("pl011").as_ptr(),
+    name: c"pl011".as_ptr(),
     version_id: 2,
     minimum_version_id: 2,
     post_load: Some(pl011_post_load),
@@ -87,14 +86,14 @@ pub static VMSTATE_PL011: VMStateDescription = VMStateDescription {
 qemu_api::declare_properties! {
     PL011_PROPERTIES,
     qemu_api::define_property!(
-        c_str!("chardev"),
+        c"chardev",
         PL011State,
         char_backend,
         unsafe { &qdev_prop_chr },
         CharBackend
     ),
     qemu_api::define_property!(
-        c_str!("migrate-clk"),
+        c"migrate-clk",
         PL011State,
         migrate_clock,
         unsafe { &qdev_prop_bool },

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

@@ -12,13 +12,11 @@
 //! See [`PL011State`](crate::device::PL011State) for the device model type and
 //! the [`registers`] module for register types.
 
-use qemu_api::c_str;
-
 mod device;
 mod device_class;
 mod registers;
 
 pub use device::pl011_create;
 
-pub const TYPE_PL011: &::std::ffi::CStr = c_str!("pl011");
+pub const TYPE_PL011: &::std::ffi::CStr = c"pl011";
-pub const TYPE_PL011_LUMINARY: &::std::ffi::CStr = c_str!("pl011_luminary");
+pub const TYPE_PL011_LUMINARY: &::std::ffi::CStr = c"pl011_luminary";

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

@@ -14,7 +14,6 @@ use qemu_api::{
         address_space_memory, address_space_stl_le, qdev_prop_bit, qdev_prop_bool,
         qdev_prop_uint32, qdev_prop_uint8,
     },
-    c_str,
     cell::{BqlCell, BqlRefCell},
     irq::InterruptSource,
     memory::{
@@ -908,7 +907,7 @@ impl ObjectImpl for HPETState {
 qemu_api::declare_properties! {
     HPET_PROPERTIES,
     qemu_api::define_property!(
-        c_str!("timers"),
+        c"timers",
         HPETState,
         num_timers,
         unsafe { &qdev_prop_uint8 },
@@ -916,7 +915,7 @@ qemu_api::declare_properties! {
         default = HPET_MIN_TIMERS
     ),
     qemu_api::define_property!(
-        c_str!("msi"),
+        c"msi",
         HPETState,
         flags,
         unsafe { &qdev_prop_bit },
@@ -925,7 +924,7 @@ qemu_api::declare_properties! {
         default = false,
     ),
     qemu_api::define_property!(
-        c_str!("hpet-intcap"),
+        c"hpet-intcap",
         HPETState,
         int_route_cap,
         unsafe { &qdev_prop_uint32 },
@@ -933,7 +932,7 @@ qemu_api::declare_properties! {
         default = 0
     ),
     qemu_api::define_property!(
-        c_str!("hpet-offset-saved"),
+        c"hpet-offset-saved",
         HPETState,
         hpet_offset_saved,
         unsafe { &qdev_prop_bool },
@@ -974,7 +973,7 @@ unsafe extern "C" fn hpet_post_load(opaque: *mut c_void, version_id: c_int) -> c
 }
 
 static VMSTATE_HPET_RTC_IRQ_LEVEL: VMStateDescription = VMStateDescription {
-    name: c_str!("hpet/rtc_irq_level").as_ptr(),
+    name: c"hpet/rtc_irq_level".as_ptr(),
     version_id: 1,
     minimum_version_id: 1,
     needed: Some(hpet_rtc_irq_level_needed),
@@ -985,7 +984,7 @@ static VMSTATE_HPET_RTC_IRQ_LEVEL: VMStateDescription = VMStateDescription {
 };
 
 static VMSTATE_HPET_OFFSET: VMStateDescription = VMStateDescription {
-    name: c_str!("hpet/offset").as_ptr(),
+    name: c"hpet/offset".as_ptr(),
     version_id: 1,
     minimum_version_id: 1,
     needed: Some(hpet_offset_needed),
@@ -996,7 +995,7 @@ static VMSTATE_HPET_OFFSET: VMStateDescription = VMStateDescription {
 };
 
 static VMSTATE_HPET_TIMER: VMStateDescription = VMStateDescription {
-    name: c_str!("hpet_timer").as_ptr(),
+    name: c"hpet_timer".as_ptr(),
     version_id: 1,
     minimum_version_id: 1,
     fields: vmstate_fields! {
@@ -1011,10 +1010,10 @@ static VMSTATE_HPET_TIMER: VMStateDescription = VMStateDescription {
     ..Zeroable::ZERO
 };
 
-const VALIDATE_TIMERS_NAME: &CStr = c_str!("num_timers must match");
+const VALIDATE_TIMERS_NAME: &CStr = c"num_timers must match";
 
 static VMSTATE_HPET: VMStateDescription = VMStateDescription {
-    name: c_str!("hpet").as_ptr(),
+    name: c"hpet".as_ptr(),
     version_id: 2,
     minimum_version_id: 1,
     pre_save: Some(hpet_pre_save),

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

@@ -7,9 +7,7 @@
 //! This library implements a device model for the IA-PC HPET (High
 //! Precision Event Timers) device in QEMU.
 
-use qemu_api::c_str;
-
 pub mod fw_cfg;
 pub mod hpet;
 
-pub const TYPE_HPET: &::std::ffi::CStr = c_str!("hpet");
+pub const TYPE_HPET: &::std::ffi::CStr = c"hpet";

rust/qemu-api/meson.build

@@ -20,7 +20,6 @@ _qemu_api_rs = static_library(
       'src/callbacks.rs',
       'src/cell.rs',
       'src/chardev.rs',
-      'src/c_str.rs',
       'src/errno.rs',
       'src/irq.rs',
       'src/memory.rs',

rust/qemu-api/src/c_str.rs

@@ -1,61 +0,0 @@
-// Copyright 2024 Red Hat, Inc.
-// Author(s): Paolo Bonzini <pbonzini@redhat.com>
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#![doc(hidden)]
-//! This module provides a macro to define a constant of type
-//! [`CStr`](std::ffi::CStr), for compatibility with versions of
-//! Rust that lack `c""` literals.
-//!
-//! Documentation is hidden because it only exposes macros, which
-//! are exported directly from `qemu_api`.
-
-#[macro_export]
-/// Given a string constant _without_ embedded or trailing NULs, return
-/// a `CStr`.
-///
-/// Needed for compatibility with Rust <1.77.
-macro_rules! c_str {
-    ($str:expr) => {{
-        const STRING: &str = concat!($str, "\0");
-        const BYTES: &[u8] = STRING.as_bytes();
-
-        // "for" is not allowed in const context... oh well,
-        // everybody loves some lisp.  This could be turned into
-        // a procedural macro if this is a problem; alternatively
-        // Rust 1.72 makes CStr::from_bytes_with_nul a const function.
-        const fn f(b: &[u8], i: usize) {
-            if i == b.len() - 1 {
-            } else if b[i] == 0 {
-                panic!("c_str argument contains NUL")
-            } else {
-                f(b, i + 1)
-            }
-        }
-        f(BYTES, 0);
-
-        // SAFETY: absence of NULs apart from the final byte was checked above
-        unsafe { std::ffi::CStr::from_bytes_with_nul_unchecked(BYTES) }
-    }};
-}
-
-#[cfg(test)]
-mod tests {
-    use std::ffi::CStr;
-
-    use crate::c_str;
-
-    #[test]
-    fn test_cstr_macro() {
-        let good = c_str!("🦀");
-        let good_bytes = b"\xf0\x9f\xa6\x80\0";
-        assert_eq!(good.to_bytes_with_nul(), good_bytes);
-    }
-
-    #[test]
-    fn test_cstr_macro_const() {
-        const GOOD: &CStr = c_str!("🦀");
-        const GOOD_BYTES: &[u8] = b"\xf0\x9f\xa6\x80\0";
-        assert_eq!(GOOD.to_bytes_with_nul(), GOOD_BYTES);
-    }
-}

rust/qemu-api/src/cell.rs

@@ -77,13 +77,13 @@
 //!
 //! ```
 //! # use qemu_api::prelude::*;
-//! # use qemu_api::{c_str, cell::BqlRefCell, irq::InterruptSource, irq::IRQState};
+//! # use qemu_api::{cell::BqlRefCell, irq::InterruptSource, irq::IRQState};
 //! # use qemu_api::{sysbus::SysBusDevice, qom::Owned, qom::ParentField};
 //! # const N_GPIOS: usize = 8;
 //! # struct PL061Registers { /* ... */ }
 //! # unsafe impl ObjectType for PL061State {
 //! #     type Class = <SysBusDevice as ObjectType>::Class;
-//! #     const TYPE_NAME: &'static std::ffi::CStr = c_str!("pl061");
+//! #     const TYPE_NAME: &'static std::ffi::CStr = c"pl061";
 //! # }
 //! struct PL061State {
 //!     parent_obj: ParentField<SysBusDevice>,

rust/qemu-api/src/lib.rs

@@ -15,7 +15,6 @@ pub mod prelude;
 
 pub mod assertions;
 pub mod bitops;
-pub mod c_str;
 pub mod callbacks;
 pub mod cell;
 pub mod chardev;

rust/qemu-api/src/vmstate.rs

@@ -427,7 +427,7 @@ unsafe impl<T: VMState, const N: usize> VMState for [T; N] {
 macro_rules! vmstate_unused {
     ($size:expr) => {{
         $crate::bindings::VMStateField {
-            name: $crate::c_str!("unused").as_ptr(),
+            name: c"unused".as_ptr(),
             size: $size,
             info: unsafe { ::core::ptr::addr_of!($crate::bindings::vmstate_info_unused_buffer) },
             flags: $crate::bindings::VMStateFlags::VMS_BUFFER,

rust/qemu-api/tests/tests.rs

@@ -6,7 +6,6 @@ use std::{ffi::CStr, ptr::addr_of};
 
 use qemu_api::{
     bindings::{module_call_init, module_init_type, qdev_prop_bool},
-    c_str,
     cell::{self, BqlCell},
     declare_properties, define_property,
     prelude::*,
@@ -21,7 +20,7 @@ mod vmstate_tests;
 
 // Test that macros can compile.
 pub static VMSTATE: VMStateDescription = VMStateDescription {
-    name: c_str!("name").as_ptr(),
+    name: c"name".as_ptr(),
     unmigratable: true,
     ..Zeroable::ZERO
 };
@@ -48,7 +47,7 @@ impl DummyClass {
 declare_properties! {
     DUMMY_PROPERTIES,
         define_property!(
-            c_str!("migrate-clk"),
+            c"migrate-clk",
             DummyState,
             migrate_clock,
             unsafe { &qdev_prop_bool },
@@ -58,7 +57,7 @@ declare_properties! {
 
 unsafe impl ObjectType for DummyState {
     type Class = DummyClass;
-    const TYPE_NAME: &'static CStr = c_str!("dummy");
+    const TYPE_NAME: &'static CStr = c"dummy";
 }
 
 impl ObjectImpl for DummyState {
@@ -92,7 +91,7 @@ pub struct DummyChildClass {
 
 unsafe impl ObjectType for DummyChildState {
     type Class = DummyChildClass;
-    const TYPE_NAME: &'static CStr = c_str!("dummy_child");
+    const TYPE_NAME: &'static CStr = c"dummy_child";
 }
 
 impl ObjectImpl for DummyChildState {

rust/qemu-api/tests/vmstate_tests.rs

@@ -14,7 +14,6 @@ use qemu_api::{
         vmstate_info_bool, vmstate_info_int32, vmstate_info_int64, vmstate_info_int8,
         vmstate_info_uint64, vmstate_info_uint8, vmstate_info_unused_buffer, VMStateFlags,
     },
-    c_str,
     cell::{BqlCell, Opaque},
     impl_vmstate_forward,
     vmstate::{VMStateDescription, VMStateField},
@@ -43,7 +42,7 @@ struct FooA {
 }
 
 static VMSTATE_FOOA: VMStateDescription = VMStateDescription {
-    name: c_str!("foo_a").as_ptr(),
+    name: c"foo_a".as_ptr(),
     version_id: 1,
     minimum_version_id: 1,
     fields: vmstate_fields! {
@@ -173,7 +172,7 @@ fn validate_foob(_state: &FooB, _version_id: u8) -> bool {
 }
 
 static VMSTATE_FOOB: VMStateDescription = VMStateDescription {
-    name: c_str!("foo_b").as_ptr(),
+    name: c"foo_b".as_ptr(),
     version_id: 2,
     minimum_version_id: 1,
     fields: vmstate_fields! {
@@ -337,7 +336,7 @@ struct FooC {
 }
 
 static VMSTATE_FOOC: VMStateDescription = VMStateDescription {
-    name: c_str!("foo_c").as_ptr(),
+    name: c"foo_c".as_ptr(),
     version_id: 3,
     minimum_version_id: 1,
     fields: vmstate_fields! {
@@ -452,13 +451,13 @@ fn validate_food_2(_state: &FooD, _version_id: u8) -> bool {
 }
 
 static VMSTATE_FOOD: VMStateDescription = VMStateDescription {
-    name: c_str!("foo_d").as_ptr(),
+    name: c"foo_d".as_ptr(),
     version_id: 3,
     minimum_version_id: 1,
     fields: vmstate_fields! {
-        vmstate_validate!(FooD, c_str!("foo_d_0"), FooD::validate_food_0),
+        vmstate_validate!(FooD, c"foo_d_0", FooD::validate_food_0),
-        vmstate_validate!(FooD, c_str!("foo_d_1"), FooD::validate_food_1),
+        vmstate_validate!(FooD, c"foo_d_1", FooD::validate_food_1),
-        vmstate_validate!(FooD, c_str!("foo_d_2"), validate_food_2),
+        vmstate_validate!(FooD, c"foo_d_2", validate_food_2),
     },
     ..Zeroable::ZERO
 };