Rollup merge of rust-lang#67666 - lzutao:ptr-null-cmp, r=dtolnay

make use of pointer::is_null

r? @Mark-Simulacrum

Author: Dylan-DPC

src/libpanic_unwind/emcc.rs

@@ -63,7 +63,7 @@ pub unsafe fn cleanup(ptr: *mut u8) -> Box<dyn Any + Send> {
 pub unsafe fn panic(data: Box<dyn Any + Send>) -> u32 {
     let sz = mem::size_of_val(&data);
     let exception = __cxa_allocate_exception(sz);
-    if exception == ptr::null_mut() {
+    if exception.is_null() {
         return uw::_URC_FATAL_PHASE1_ERROR as u32;
     }
     ptr::write(exception as *mut _, data);

src/libstd/sys/hermit/os.rs

@@ -77,13 +77,17 @@ pub fn init_environment(env: *const *const i8) {
     unsafe {
         ENV = Some(Mutex::new(HashMap::new()));
 
+        if env.is_null() {
+            return;
+        }
+
         let mut guard = ENV.as_ref().unwrap().lock().unwrap();
         let mut environ = env;
-        while environ != ptr::null() && *environ != ptr::null() {
+        while !(*environ).is_null() {
             if let Some((key, value)) = parse(CStr::from_ptr(*environ).to_bytes()) {
                 guard.insert(key, value);
             }
-            environ = environ.offset(1);
+            environ = environ.add(1);
         }
     }
 

src/libstd/sys/hermit/thread_local.rs

@@ -18,14 +18,14 @@ static KEYS_LOCK: Mutex = Mutex::new();
 static mut LOCALS: *mut BTreeMap<Key, *mut u8> = ptr::null_mut();
 
 unsafe fn keys() -> &'static mut BTreeMap<Key, Option<Dtor>> {
-    if KEYS == ptr::null_mut() {
+    if KEYS.is_null() {
         KEYS = Box::into_raw(Box::new(BTreeMap::new()));
     }
     &mut *KEYS
 }
 
 unsafe fn locals() -> &'static mut BTreeMap<Key, *mut u8> {
-    if LOCALS == ptr::null_mut() {
+    if LOCALS.is_null() {
         LOCALS = Box::into_raw(Box::new(BTreeMap::new()));
     }
     &mut *LOCALS

src/libstd/sys/sgx/abi/tls.rs

@@ -70,7 +70,7 @@ impl<'a> Drop for ActiveTls<'a> {
             any_non_null_dtor = false;
             for (value, dtor) in TLS_KEY_IN_USE.iter().filter_map(&value_with_destructor) {
                 let value = value.replace(ptr::null_mut());
-                if value != ptr::null_mut() {
+                if !value.is_null() {
                     any_non_null_dtor = true;
                     unsafe { dtor(value) }
                 }

src/libstd/sys/unix/os.rs

@@ -480,11 +480,13 @@ pub fn env() -> Env {
         let _guard = env_lock();
         let mut environ = *environ();
         let mut result = Vec::new();
-        while environ != ptr::null() && *environ != ptr::null() {
-            if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
-                result.push(key_value);
+        if !environ.is_null() {
+            while !(*environ).is_null() {
+                if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
+                    result.push(key_value);
+                }
+                environ = environ.add(1);
             }
-            environ = environ.offset(1);
         }
         return Env { iter: result.into_iter(), _dont_send_or_sync_me: PhantomData };
     }

src/libstd/sys/vxworks/os.rs

@@ -226,15 +226,15 @@ pub fn env() -> Env {
     unsafe {
         let _guard = env_lock();
         let mut environ = *environ();
-        if environ == ptr::null() {
+        if environ.is_null() {
             panic!("os::env() failure getting env string from OS: {}", io::Error::last_os_error());
         }
         let mut result = Vec::new();
-        while *environ != ptr::null() {
+        while !(*environ).is_null() {
             if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
                 result.push(key_value);
             }
-            environ = environ.offset(1);
+            environ = environ.add(1);
         }
         return Env { iter: result.into_iter(), _dont_send_or_sync_me: PhantomData };
     }

src/libstd/sys/wasi/os.rs

@@ -107,11 +107,13 @@ pub fn env() -> Env {
         let _guard = env_lock();
         let mut environ = libc::environ;
         let mut result = Vec::new();
-        while environ != ptr::null_mut() && *environ != ptr::null_mut() {
-            if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
-                result.push(key_value);
+        if !environ.is_null() {
+            while !(*environ).is_null() {
+                if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
+                    result.push(key_value);
+                }
+                environ = environ.add(1);
             }
-            environ = environ.offset(1);
         }
         return Env { iter: result.into_iter(), _dont_send_or_sync_me: PhantomData };
     }

src/libstd/sys/windows/os.rs

@@ -43,7 +43,7 @@ pub fn error_string(mut errnum: i32) -> String {
             ];
             module = c::GetModuleHandleW(NTDLL_DLL.as_ptr());
 
-            if module != ptr::null_mut() {
+            if !module.is_null() {
                 errnum ^= c::FACILITY_NT_BIT as i32;
                 flags = c::FORMAT_MESSAGE_FROM_HMODULE;
             }