Update the global lint configuration

.github/workflows/ci.yaml

@@ -107,10 +107,13 @@ jobs:
         run: |
           set -eux
           if [ "${{ matrix.toolchain }}" = "1.65.0" ]; then
-              # Remove `-Dwarnings` at the MSRV since lints may be different, and allow
-              # `improper_ctypes` since pointers to ZSTs got the warning prior to 1.72.
-              # FIXME(msrv): remove this flag when possible.
-              export RUSTFLAGS="-Aimproper_ctypes"
+              # * Remove `-Dwarnings` at the MSRV since lints may be different
+              # * Allow `improper_ctypes` since pointers to ZSTs got the warning prior
+              #   to 1.72.
+              # * Enable `unknown_lints` since we have some config not known at this
+              #   version.
+              # FIXME(msrv): update this list when possible.
+              export RUSTFLAGS="-Aimproper_ctypes -Aunknown_lints"
               # Remove `ctest` which uses the 2024 edition
               perl -i -ne 'print unless /"ctest(-test)?",/ || /"libc-test",/' Cargo.toml
           fi

src/fuchsia/mod.rs

@@ -1606,7 +1606,7 @@ pub const EPOLLWRBAND: c_int = 0x200;
 pub const EPOLLMSG: c_int = 0x400;
 pub const EPOLLERR: c_int = 0x8;
 pub const EPOLLHUP: c_int = 0x10;
-pub const EPOLLET: c_int = 0x80000000;
+pub const EPOLLET: c_int = u32_cast_int(0x80000000);
 
 pub const EPOLL_CTL_ADD: c_int = 1;
 pub const EPOLL_CTL_MOD: c_int = 3;
@@ -1698,7 +1698,7 @@ pub const CLONE_NEWIPC: c_int = 0x08000000;
 pub const CLONE_NEWUSER: c_int = 0x10000000;
 pub const CLONE_NEWPID: c_int = 0x20000000;
 pub const CLONE_NEWNET: c_int = 0x40000000;
-pub const CLONE_IO: c_int = 0x80000000;
+pub const CLONE_IO: c_int = u32_cast_int(0x80000000);
 pub const CLONE_NEWCGROUP: c_int = 0x02000000;
 
 pub const WNOHANG: c_int = 0x00000001;
@@ -1734,7 +1734,7 @@ pub const PTRACE_EVENT_SECCOMP: c_int = 7;
 
 pub const __WNOTHREAD: c_int = 0x20000000;
 pub const __WALL: c_int = 0x40000000;
-pub const __WCLONE: c_int = 0x80000000;
+pub const __WCLONE: c_int = u32_cast_int(0x80000000);
 
 pub const SPLICE_F_MOVE: c_uint = 0x01;
 pub const SPLICE_F_NONBLOCK: c_uint = 0x02;
@@ -2551,7 +2551,7 @@ pub const EPROTO: c_int = 71;
 pub const EDOTDOT: c_int = 73;
 
 pub const SA_NODEFER: c_int = 0x40000000;
-pub const SA_RESETHAND: c_int = 0x80000000;
+pub const SA_RESETHAND: c_int = u32_cast_int(0x80000000);
 pub const SA_RESTART: c_int = 0x10000000;
 pub const SA_NOCLDSTOP: c_int = 0x00000001;
 

src/hermit.rs

@@ -157,7 +157,7 @@ pub const F_SETFL: i32 = 4;
 
 pub const FD_CLOEXEC: i32 = 1;
 
-pub const FIONBIO: i32 = 0x8008667e;
+pub const FIONBIO: i32 = u32_cast_int(0x8008667e);
 
 pub const FUTEX_RELATIVE_TIMEOUT: u32 = 1;
 

src/lib.rs

@@ -144,30 +144,26 @@
 //! practice, breakage is rare and following the above-discussed [Usage Guidelines](#usage-guidelines)
 //! means that most `libc` users will never encounter a problem.
 
+// Make it a bit easier to build without Cargo
 #![crate_name = "libc"]
 #![crate_type = "rlib"]
-#![allow(
-    renamed_and_removed_lints, // Keep this order.
-    unknown_lints, // Keep this order.
-    nonstandard_style,
-    overflowing_literals,
-    unused_macros,
-    unused_macro_rules,
-)]
-#![warn(
-    missing_copy_implementations,
-    missing_debug_implementations,
-    safe_packed_borrows
-)]
-// Prepare for a future upgrade
+// Pretty much all C API doesn't match Rust conventions.
+#![allow(nonstandard_style)]
+// Not all macros and all patterns are used on all targets.
+#![allow(unused_macros)]
+#![allow(unused_macro_rules)]
+// All traits should be `Copy` and `Debug`.
+#![warn(missing_copy_implementations)]
+#![warn(missing_debug_implementations)]
+// Downgrade deny to a warning.
+#![warn(overflowing_literals)]
+// Prepare for a future upgrade.
 #![warn(rust_2024_compatibility)]
-// Things missing for 2024 that are blocked on MSRV or breakage
-#![allow(
-    missing_unsafe_on_extern,
-    edition_2024_expr_fragment_specifier,
-    // Allowed globally, the warning is enabled in individual modules as we work through them
-    unsafe_op_in_unsafe_fn
-)]
+// Things missing for 2024 that are blocked on MSRV or breakage.
+#![allow(missing_unsafe_on_extern)]
+#![allow(edition_2024_expr_fragment_specifier)]
+// Allowed globally, the warning is enabled in individual modules as we work through them
+#![allow(unsafe_op_in_unsafe_fn)]
 #![cfg_attr(libc_deny_warnings, deny(warnings))]
 // Attributes needed when building as part of the standard library
 #![cfg_attr(feature = "rustc-dep-of-std", feature(link_cfg, no_core))]

src/macros.rs

@@ -87,6 +87,7 @@ macro_rules! prelude {
             pub(crate) use core::prelude::v1::derive;
             #[allow(unused_imports)]
             pub(crate) use core::{
+                assert,
                 cfg,
                 fmt,
                 hash,
@@ -105,8 +106,14 @@ macro_rules! prelude {
                 size_of_val,
             };
 
+            #[allow(unused_imports)]
+            #[cfg(any(target_os = "linux", target_os = "android", target_os = "l4re"))]
+            pub(crate) use crate::types::u32_cast_ioctl;
             #[allow(unused_imports)]
             pub(crate) use crate::types::{
+                u16_cast_short,
+                u32_cast_int,
+                u32_cast_long,
                 CEnumRepr,
                 Padding,
             };

src/new/linux_uapi/linux/futex.rs

@@ -51,7 +51,7 @@ pub const FUTEX_WAITERS: u32 = 0x80000000;
 pub const FUTEX_OWNER_DIED: u32 = 0x40000000;
 pub const FUTEX_TID_MASK: u32 = 0x3fffffff;
 
-pub const FUTEX_BITSET_MATCH_ANY: c_int = 0xffffffff;
+pub const FUTEX_BITSET_MATCH_ANY: c_int = u32_cast_int(0xffffffff);
 
 pub const FUTEX_OP_SET: c_int = 0;
 pub const FUTEX_OP_ADD: c_int = 1;

src/new/qurt/limits.rs

@@ -13,15 +13,15 @@ pub const UCHAR_MAX: c_uchar = 255;
 
 // Integer properties
 pub const INT_MAX: c_int = 2147483647;
-pub const INT_MIN: c_int = (-2147483647 - 1);
+pub const INT_MIN: c_int = -2147483647 - 1;
 pub const UINT_MAX: c_uint = 4294967295;
 
 pub const LONG_MAX: c_long = 2147483647;
-pub const LONG_MIN: c_long = (-2147483647 - 1);
+pub const LONG_MIN: c_long = -2147483647 - 1;
 pub const ULONG_MAX: c_ulong = 4294967295;
 
 pub const SHRT_MAX: c_short = 32767;
-pub const SHRT_MIN: c_short = (-32768);
+pub const SHRT_MIN: c_short = -32768;
 pub const USHRT_MAX: c_ushort = 65535;
 
 // POSIX Limits

src/solid/mod.rs

@@ -207,10 +207,10 @@ pub const S_IWRITE: c_short = 0o0200;
 pub const S_IREAD: c_short = 0o0400;
 pub const S_IFCHR: c_short = 0o2_0000;
 pub const S_IFDIR: c_short = 0o4_0000;
-pub const S_IFMT: c_short = 0o16_0000;
+pub const S_IFMT: c_short = u16_cast_short(0o16_0000);
 pub const S_IFIFO: c_short = 0o1_0000;
 pub const S_IFBLK: c_short = 0o6_0000;
-pub const S_IFREG: c_short = 0o10_0000;
+pub const S_IFREG: c_short = u16_cast_short(0o10_0000);
 
 pub const LC_ALL: c_int = 0;
 pub const LC_COLLATE: c_int = 1;

src/types.rs

@@ -65,3 +65,37 @@ pub(crate) type CEnumRepr = c_int;
 #[cfg(not(target_env = "msvc"))]
 #[allow(unused)]
 pub(crate) type CEnumRepr = c_uint;
+
+/// Used to avoid `overflowing_literals` when the value is in-range for the unsigned number but
+/// out-of-range for signed.
+#[allow(unused)]
+pub(crate) const fn u16_cast_short(x: u16) -> c_short {
+    assert!(size_of::<u16>() <= size_of::<c_short>()); // Should always be true
+    x as i16
+}
+
+/// Used to avoid `overflowing_literals` when the value is in-range for the unsigned number but
+/// out-of-range for signed.
+#[allow(unused)]
+pub(crate) const fn u32_cast_int(x: u32) -> c_int {
+    // May not be true on 16-bit platforms, but should be everywhere this is used.
+    assert!(size_of::<u32>() <= size_of::<c_int>());
+    x as i32
+}
+
+/// Used to avoid `overflowing_literals` when the value is in-range for the unsigned number but
+/// out-of-range for signed.
+#[allow(unused)]
+pub(crate) const fn u32_cast_long(x: u32) -> c_long {
+    assert!(size_of::<u32>() <= size_of::<c_long>()); // Should always be true
+    x as c_long
+}
+
+/// Used to avoid `overflowing_literals` when the value is in-range for the unsigned number but
+/// out-of-range for signed.
+#[allow(unused)]
+#[cfg(any(target_os = "linux", target_os = "android", target_os = "l4re"))]
+pub(crate) const fn u32_cast_ioctl(x: u32) -> crate::Ioctl {
+    assert!(size_of::<u32>() <= size_of::<crate::Ioctl>()); // Should always be true
+    x as crate::Ioctl
+}