Auto merge of #116463 - ChrisDenton:nlibc, r=workingjubilee

Remove libc

We don't use much libc on Windows and it seemed silly to keep if for the sake of [two well documented constants](https://learn.microsoft.com/en-us/cpp/c-runtime-library/exit-success-exit-failure?view=msvc-170).

library/std/src/sys/windows/c.rs

@@ -46,6 +46,10 @@
 pub use LINGER as linger;
 pub use TIMEVAL as timeval;
 
+// https://learn.microsoft.com/en-us/cpp/c-runtime-library/exit-success-exit-failure?view=msvc-170
+pub const EXIT_SUCCESS: u32 = 0;
+pub const EXIT_FAILURE: u32 = 1;
+
 pub const CONDITION_VARIABLE_INIT: CONDITION_VARIABLE = CONDITION_VARIABLE { Ptr: ptr::null_mut() };
 pub const SRWLOCK_INIT: SRWLOCK = SRWLOCK { Ptr: ptr::null_mut() };
 pub const INIT_ONCE_STATIC_INIT: INIT_ONCE = INIT_ONCE { Ptr: ptr::null_mut() };

library/std/src/sys/windows/cmath.rs

@@ -1,6 +1,6 @@
 #![cfg(not(test))]
 
-use libc::{c_double, c_float, c_int};
+use core::ffi::{c_double, c_float, c_int};
 
 extern "C" {
     pub fn acos(n: c_double) -> c_double;
@@ -33,7 +33,7 @@
 
 #[cfg(not(all(target_env = "msvc", target_arch = "x86")))]
 mod shims {
-    use libc::c_float;
+    use core::ffi::c_float;
 
     extern "C" {
         pub fn acosf(n: c_float) -> c_float;
@@ -52,7 +52,7 @@ mod shims {
 // back to f32. While not precisely correct should be "correct enough" for now.
 #[cfg(all(target_env = "msvc", target_arch = "x86"))]
 mod shims {
-    use libc::c_float;
+    use core::ffi::c_float;
 
     #[inline]
     pub unsafe fn acosf(n: c_float) -> c_float {

library/std/src/sys/windows/fs.rs

@@ -16,6 +16,8 @@
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::thread;
 
+use core::ffi::c_void;
+
 use super::path::maybe_verbatim;
 use super::to_u16s;
 
@@ -371,7 +373,7 @@ pub fn file_attr(&self) -> io::Result<FileAttr> {
             cvt(c::GetFileInformationByHandleEx(
                 self.handle.as_raw_handle(),
                 c::FileBasicInfo,
-                &mut info as *mut _ as *mut libc::c_void,
+                &mut info as *mut _ as *mut c_void,
                 size as c::DWORD,
             ))?;
             let mut attr = FileAttr {
@@ -399,7 +401,7 @@ pub fn file_attr(&self) -> io::Result<FileAttr> {
             cvt(c::GetFileInformationByHandleEx(
                 self.handle.as_raw_handle(),
                 c::FileStandardInfo,
-                &mut info as *mut _ as *mut libc::c_void,
+                &mut info as *mut _ as *mut c_void,
                 size as c::DWORD,
             ))?;
             attr.file_size = info.AllocationSize as u64;
@@ -624,7 +626,7 @@ fn basic_info(&self) -> io::Result<c::FILE_BASIC_INFO> {
             cvt(c::GetFileInformationByHandleEx(
                 self.handle.as_raw_handle(),
                 c::FileBasicInfo,
-                &mut info as *mut _ as *mut libc::c_void,
+                &mut info as *mut _ as *mut c_void,
                 size as c::DWORD,
             ))?;
             Ok(info)

library/std/src/sys/windows/io.rs

@@ -3,7 +3,7 @@
 use crate::os::windows::io::{AsHandle, AsRawHandle, BorrowedHandle};
 use crate::slice;
 use crate::sys::c;
-use libc;
+use core::ffi::c_void;
 
 #[derive(Copy, Clone)]
 #[repr(transparent)]
@@ -136,7 +136,7 @@ struct FILE_NAME_INFO {
     let res = c::GetFileInformationByHandleEx(
         handle,
         c::FileNameInfo,
-        &mut name_info as *mut _ as *mut libc::c_void,
+        &mut name_info as *mut _ as *mut c_void,
         size_of::<FILE_NAME_INFO>() as u32,
     );
     if res == 0 {

library/std/src/sys/windows/net.rs

@@ -15,7 +15,7 @@
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::Duration;
 
-use libc::{c_int, c_long, c_ulong, c_ushort};
+use core::ffi::{c_int, c_long, c_ulong, c_ushort};
 
 pub type wrlen_t = i32;
 

library/std/src/sys/windows/process.rs

@@ -19,8 +19,7 @@
 use crate::ptr;
 use crate::sync::Mutex;
 use crate::sys::args::{self, Arg};
-use crate::sys::c;
-use crate::sys::c::NonZeroDWORD;
+use crate::sys::c::{self, NonZeroDWORD, EXIT_FAILURE, EXIT_SUCCESS};
 use crate::sys::cvt;
 use crate::sys::fs::{File, OpenOptions};
 use crate::sys::handle::Handle;
@@ -30,7 +29,7 @@
 use crate::sys_common::process::{CommandEnv, CommandEnvs};
 use crate::sys_common::IntoInner;
 
-use libc::{c_void, EXIT_FAILURE, EXIT_SUCCESS};
+use core::ffi::c_void;
 
 ////////////////////////////////////////////////////////////////////////////////
 // Command

library/std/src/sys/windows/thread.rs

@@ -10,7 +10,7 @@
 use crate::sys_common::FromInner;
 use crate::time::Duration;
 
-use libc::c_void;
+use core::ffi::c_void;
 
 use super::to_u16s;