rollup merge of #21444: petrochenkov/null

Conflicts:
	src/libstd/sync/mpsc/select.rs

5 files changed, 7 insertions, 5 deletions

diff --git a/src/libstd/sys/unix/backtrace.rs b/src/libstd/sys/unix/backtrace.rs
index e6007a4d43c..cb2edf50ebd 100644
--- a/src/libstd/sys/unix/backtrace.rs
+++ b/src/libstd/sys/unix/backtrace.rs
@@ -353,7 +353,7 @@ fn print(w: &mut Writer, idx: int, addr: *mut libc::c_void) -> IoResult<()> {
     if state.is_null() {
         return output(w, idx, addr, None)
     }
-    let mut data = 0 as *const libc::c_char;
+    let mut data = ptr::null();
     let data_addr = &mut data as *mut *const libc::c_char;
     let ret = unsafe {
         backtrace_syminfo(state, addr as libc::uintptr_t,
diff --git a/src/libstd/sys/unix/condvar.rs b/src/libstd/sys/unix/condvar.rs
index 85a65bbef50..3bc41473152 100644
--- a/src/libstd/sys/unix/condvar.rs
+++ b/src/libstd/sys/unix/condvar.rs
@@ -10,6 +10,7 @@
 
 use cell::UnsafeCell;
 use libc;
+use ptr;
 use std::option::Option::{Some, None};
 use sys::mutex::{self, Mutex};
 use sys::time;
@@ -62,7 +63,7 @@ impl Condvar {
         // time.
         let mut sys_now = libc::timeval { tv_sec: 0, tv_usec: 0 };
         let stable_now = time::SteadyTime::now();
-        let r = ffi::gettimeofday(&mut sys_now, 0 as *mut _);
+        let r = ffi::gettimeofday(&mut sys_now, ptr::null_mut());
         debug_assert_eq!(r, 0);
 
         let seconds = NumCast::from(dur.num_seconds());
diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index c53f9d22790..dd478347f81 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -19,6 +19,7 @@ use io::{Read, Truncate, SeekCur, SeekSet, ReadWrite, SeekEnd, Append};
 use io;
 use libc::{self, c_int, c_void};
 use mem;
+use ptr;
 use sys::retry;
 use sys_common::{keep_going, eof, mkerr_libc};
 
@@ -207,7 +208,7 @@ pub fn readdir(p: &Path) -> IoResult<Vec<Path>> {
 
     if dir_ptr as uint != 0 {
         let mut paths = vec!();
-        let mut entry_ptr = 0 as *mut dirent_t;
+        let mut entry_ptr = ptr::null_mut();
         while unsafe { readdir_r(dir_ptr, ptr, &mut entry_ptr) == 0 } {
             if entry_ptr.is_null() { break }
             paths.push(unsafe {
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 175c4e2e353..2c25af055ee 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -143,7 +143,7 @@ pub unsafe fn get_env_pairs() -> Vec<Vec<u8>> {
                os::last_os_error());
     }
     let mut result = Vec::new();
-    while *environ != 0 as *const _ {
+    while *environ != ptr::null() {
         let env_pair = ffi::c_str_to_bytes(&*environ).to_vec();
         result.push(env_pair);
         environ = environ.offset(1);
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs
index 36bf696dba5..0eab27de43a 100644
--- a/src/libstd/sys/unix/process.rs
+++ b/src/libstd/sys/unix/process.rs
@@ -251,7 +251,7 @@ impl Process {
                             fn setgroups(ngroups: libc::c_int,
                                          ptr: *const libc::c_void) -> libc::c_int;
                         }
-                        let _ = setgroups(0, 0 as *const libc::c_void);
+                        let _ = setgroups(0, ptr::null());
 
                         if libc::setuid(u as libc::uid_t) != 0 {
                             fail(&mut output);