chore: apply some clippy lints

(backport <rust-lang#4415>)
[ drop changes around the FreeBSD version in build.rs since the logic
  isn't the same - Trevor ]
(cherry picked from commit a283b9e)

Author: nyurik

Cargo.toml

@@ -159,15 +159,21 @@ members = [
 unused_qualifications = "allow"
 
 [lints.clippy]
-missing_safety_doc = "allow"
+# Enable pedantic lints - use this manually once in a while, but don't enable by default
+# pedantic = { level = "warn", priority = -1 }
 
-# FIXME(clippy): all these are default lints and should probably be fixed
-identity_op = "allow"
-if_same_then_else = "allow"
-non_minimal_cfg = "allow"
-precedence = "allow"
-redundant_field_names = "allow"
-redundant_static_lifetimes = "allow"
-unnecessary_cast = "allow"
-unused_unit = "allow"
-zero_ptr = "allow"
+# We are okay with the current state of these lints
+explicit_iter_loop = "warn"
+identity_op = "allow"  # some expressions like `0 | x` are clearer for bit ops
+manual_assert = "warn"
+map_unwrap_or = "warn"
+missing_safety_doc = "allow"  # safety? in libc? seriously?
+non_minimal_cfg = "allow"  # for some reason cfg_if! sometimes trigger this
+ptr_as_ptr = "warn"
+unnecessary_semicolon = "warn"
+
+# FIXME(clippy): these should be fixed if possible
+expl_impl_clone_on_copy = "allow"
+uninlined_format_args = "allow"
+unnecessary_cast = "allow"  # some casts like `as usize` are only needed for some targets
+used_underscore_binding = "allow"

build.rs

@@ -4,7 +4,7 @@ use std::{env, str};
 // List of cfgs this build script is allowed to set. The list is needed to support check-cfg, as we
 // need to know all the possible cfgs that this script will set. If you need to set another cfg
 // make sure to add it to this list as well.
-const ALLOWED_CFGS: &'static [&'static str] = &[
+const ALLOWED_CFGS: &[&str] = &[
     "emscripten_old_stat_abi",
     "espidf_time32",
     "freebsd10",
@@ -25,7 +25,7 @@ const ALLOWED_CFGS: &'static [&'static str] = &[
 ];
 
 // Extra values to allow for check-cfg.
-const CHECK_CFG_EXTRA: &'static [(&'static str, &'static [&'static str])] = &[
+const CHECK_CFG_EXTRA: &[(&str, &[&str])] = &[
     (
         "target_os",
         &[
@@ -169,12 +169,11 @@ fn rustc_version_cmd(is_clippy_driver: bool) -> Output {
 
     let output = cmd.output().expect("Failed to get rustc version");
 
-    if !output.status.success() {
-        panic!(
-            "failed to run rustc: {}",
-            String::from_utf8_lossy(output.stderr.as_slice())
-        );
-    }
+    assert!(
+        output.status.success(),
+        "failed to run rustc: {}",
+        String::from_utf8_lossy(output.stderr.as_slice())
+    );
 
     output
 }
@@ -201,9 +200,11 @@ fn rustc_minor_nightly() -> (u32, bool) {
 
     let mut pieces = version.split('.');
 
-    if pieces.next() != Some("rustc 1") {
-        panic!("Failed to get rustc version");
-    }
+    assert_eq!(
+        pieces.next(),
+        Some("rustc 1"),
+        "Failed to get rustc version"
+    );
 
     let minor = pieces.next();
 
@@ -213,9 +214,9 @@ fn rustc_minor_nightly() -> (u32, bool) {
     // since a nightly build should either come from CI
     // or a git checkout
     let nightly_raw = otry!(pieces.next()).split('-').nth(1);
-    let nightly = nightly_raw
-        .map(|raw| raw.starts_with("dev") || raw.starts_with("nightly"))
-        .unwrap_or(false);
+    let nightly = nightly_raw.map_or(false, |raw| {
+        raw.starts_with("dev") || raw.starts_with("nightly")
+    });
     let minor = otry!(otry!(minor).parse().ok());
 
     (minor, nightly)
@@ -266,8 +267,9 @@ fn emcc_version_code() -> Option<u64> {
 }
 
 fn set_cfg(cfg: &str) {
-    if !ALLOWED_CFGS.contains(&cfg) {
-        panic!("trying to set cfg {cfg}, but it is not in ALLOWED_CFGS");
-    }
+    assert!(
+        ALLOWED_CFGS.contains(&cfg),
+        "trying to set cfg {cfg}, but it is not in ALLOWED_CFGS",
+    );
     println!("cargo:rustc-cfg={cfg}");
 }

src/fuchsia/mod.rs

@@ -3429,9 +3429,9 @@ f! {
 
     pub fn CMSG_NXTHDR(mhdr: *const msghdr, cmsg: *const cmsghdr) -> *mut cmsghdr {
         if ((*cmsg).cmsg_len as size_t) < mem::size_of::<cmsghdr>() {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         } else if __CMSG_NEXT(cmsg).add(mem::size_of::<cmsghdr>()) >= __MHDR_END(mhdr) {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         } else {
             __CMSG_NEXT(cmsg).cast()
         }
@@ -3441,7 +3441,7 @@ f! {
         if (*mhdr).msg_controllen as size_t >= mem::size_of::<cmsghdr>() {
             (*mhdr).msg_control.cast()
         } else {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         }
     }
 

src/unix/aix/mod.rs

@@ -2442,7 +2442,7 @@ f! {
         if (*mhdr).msg_controllen as usize >= mem::size_of::<cmsghdr>() {
             (*mhdr).msg_control as *mut cmsghdr
         } else {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         }
     }
 
@@ -2453,7 +2453,7 @@ f! {
             if (cmsg as usize + (*cmsg).cmsg_len as usize + mem::size_of::<cmsghdr>())
                 > ((*mhdr).msg_control as usize + (*mhdr).msg_controllen as usize)
             {
-                0 as *mut cmsghdr
+                core::ptr::null_mut::<cmsghdr>()
             } else {
                 // AIX does not have any alignment/padding for ancillary data, so we don't need _CMSG_ALIGN here.
                 (cmsg as usize + (*cmsg).cmsg_len as usize) as *mut cmsghdr

src/unix/bsd/apple/mod.rs

@@ -1691,7 +1691,7 @@ impl siginfo_t {
             si_value: crate::sigval,
         }
 
-        (*(self as *const siginfo_t as *const siginfo_timer)).si_value
+        (*(self as *const siginfo_t).cast::<siginfo_timer>()).si_value
     }
 
     pub unsafe fn si_pid(&self) -> crate::pid_t {
@@ -5635,7 +5635,7 @@ pub const VMADDR_PORT_ANY: c_uint = 0xFFFFFFFF;
 
 const fn __DARWIN_ALIGN32(p: usize) -> usize {
     const __DARWIN_ALIGNBYTES32: usize = mem::size_of::<u32>() - 1;
-    p + __DARWIN_ALIGNBYTES32 & !__DARWIN_ALIGNBYTES32
+    (p + __DARWIN_ALIGNBYTES32) & !__DARWIN_ALIGNBYTES32
 }
 
 pub const THREAD_EXTENDED_POLICY_COUNT: mach_msg_type_number_t =
@@ -5710,7 +5710,7 @@ f! {
     pub fn CMSG_NXTHDR(mhdr: *const crate::msghdr, cmsg: *const cmsghdr) -> *mut cmsghdr {
         if cmsg.is_null() {
             return crate::CMSG_FIRSTHDR(mhdr);
-        };
+        }
         let cmsg_len = (*cmsg).cmsg_len as usize;
         let next = cmsg as usize + __DARWIN_ALIGN32(cmsg_len);
         let max = (*mhdr).msg_control as usize + (*mhdr).msg_controllen as usize;

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

@@ -1560,7 +1560,7 @@ f! {
         if next <= max {
             (cmsg as usize + _CMSG_ALIGN((*cmsg).cmsg_len as usize)) as *mut cmsghdr
         } else {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         }
     }
 

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

@@ -4930,7 +4930,7 @@ const_fn! {
 
 f! {
     pub fn CMSG_DATA(cmsg: *const cmsghdr) -> *mut c_uchar {
-        (cmsg as *mut c_uchar).offset(_ALIGN(mem::size_of::<cmsghdr>()) as isize)
+        (cmsg as *mut c_uchar).add(_ALIGN(mem::size_of::<cmsghdr>()))
     }
 
     pub {const} fn CMSG_LEN(length: c_uint) -> c_uint {
@@ -4945,7 +4945,7 @@ f! {
             cmsg as usize + _ALIGN((*cmsg).cmsg_len as usize) + _ALIGN(mem::size_of::<cmsghdr>());
         let max = (*mhdr).msg_control as usize + (*mhdr).msg_controllen as usize;
         if next > max {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         } else {
             (cmsg as usize + _ALIGN((*cmsg).cmsg_len as usize)) as *mut cmsghdr
         }
@@ -4992,14 +4992,12 @@ f! {
         let bitset_bits = 8 * mem::size_of::<c_long>();
         let (idx, offset) = (cpu / bitset_bits, cpu % bitset_bits);
         cpuset.__bits[idx] |= 1 << offset;
-        ()
     }
 
     pub fn CPU_CLR(cpu: usize, cpuset: &mut cpuset_t) -> () {
         let bitset_bits = 8 * mem::size_of::<c_long>();
         let (idx, offset) = (cpu / bitset_bits, cpu % bitset_bits);
         cpuset.__bits[idx] &= !(1 << offset);
-        ()
     }
 
     pub fn CPU_ISSET(cpu: usize, cpuset: &cpuset_t) -> bool {

src/unix/bsd/mod.rs

@@ -596,7 +596,7 @@ pub const RTAX_BRD: c_int = 7;
 f! {
     pub fn CMSG_FIRSTHDR(mhdr: *const crate::msghdr) -> *mut cmsghdr {
         if (*mhdr).msg_controllen as usize >= mem::size_of::<cmsghdr>() {
-            (*mhdr).msg_control as *mut cmsghdr
+            (*mhdr).msg_control.cast::<cmsghdr>()
         } else {
             core::ptr::null_mut()
         }
@@ -623,7 +623,7 @@ f! {
     }
 
     pub fn FD_ZERO(set: *mut fd_set) -> () {
-        for slot in (*set).fds_bits.iter_mut() {
+        for slot in &mut (*set).fds_bits {
             *slot = 0;
         }
     }

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

@@ -2423,7 +2423,7 @@ const_fn! {
 
 f! {
     pub fn CMSG_DATA(cmsg: *const cmsghdr) -> *mut c_uchar {
-        (cmsg as *mut c_uchar).offset(_ALIGN(mem::size_of::<cmsghdr>()) as isize)
+        (cmsg as *mut c_uchar).add(_ALIGN(mem::size_of::<cmsghdr>()))
     }
 
     pub {const} fn CMSG_LEN(length: c_uint) -> c_uint {
@@ -2438,7 +2438,7 @@ f! {
             cmsg as usize + _ALIGN((*cmsg).cmsg_len as usize) + _ALIGN(mem::size_of::<cmsghdr>());
         let max = (*mhdr).msg_control as usize + (*mhdr).msg_controllen as usize;
         if next > max {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         } else {
             (cmsg as usize + _ALIGN((*cmsg).cmsg_len as usize)) as *mut cmsghdr
         }

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

@@ -1957,7 +1957,7 @@ f! {
             cmsg as usize + _ALIGN((*cmsg).cmsg_len as usize) + _ALIGN(mem::size_of::<cmsghdr>());
         let max = (*mhdr).msg_control as usize + (*mhdr).msg_controllen as usize;
         if next > max {
-            0 as *mut cmsghdr
+            core::ptr::null_mut::<cmsghdr>()
         } else {
             (cmsg as usize + _ALIGN((*cmsg).cmsg_len as usize)) as *mut cmsghdr
         }