Rollup merge of #84179 - CDirkx:dont_send_sync, r=m-ou-se

Explicitly implement `!Send` and `!Sync` for `sys::{Args, Env}`

Remove the field `_dont_send_or_sync_me: PhantomData<*mut ()>` in favor of an explicit implementation of `!Send` and `!Sync`.

library/std/src/sys/hermit/args.rs

 use crate::ffi::OsString;
 use crate::fmt;
-use crate::marker::PhantomData;
 use crate::vec;
 
 /// One-time global initialization.
@@ -20,7 +19,6 @@ pub fn args() -> Args {
 
 pub struct Args {
     iter: vec::IntoIter<OsString>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
 impl fmt::Debug for Args {
@@ -29,6 +27,9 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     }
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl Iterator for Args {
     type Item = OsString;
     fn next(&mut self) -> Option<OsString> {
@@ -54,7 +55,6 @@ fn next_back(&mut self) -> Option<OsString> {
 mod imp {
     use super::Args;
     use crate::ffi::{CStr, OsString};
-    use crate::marker::PhantomData;
     use crate::ptr;
     use crate::sys_common::os_str_bytes::*;
 
@@ -77,7 +77,7 @@ pub unsafe fn cleanup() {
     }
 
     pub fn args() -> Args {
-        Args { iter: clone().into_iter(), _dont_send_or_sync_me: PhantomData }
+        Args { iter: clone().into_iter() }
     }
 
     fn clone() -> Vec<OsString> {

library/std/src/sys/hermit/os.rs

@@ -110,9 +110,11 @@ fn parse(input: &[u8]) -> Option<(OsString, OsString)> {
 
 pub struct Env {
     iter: vec::IntoIter<(OsString, OsString)>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
+impl !Send for Env {}
+impl !Sync for Env {}
+
 impl Iterator for Env {
     type Item = (OsString, OsString);
     fn next(&mut self) -> Option<(OsString, OsString)> {
@@ -134,7 +136,7 @@ pub fn env() -> Env {
             result.push((key.clone(), value.clone()));
         }
 
-        return Env { iter: result.into_iter(), _dont_send_or_sync_me: PhantomData };
+        return Env { iter: result.into_iter() };
     }
 }
 

library/std/src/sys/unix/args.rs

@@ -7,7 +7,6 @@
 
 use crate::ffi::OsString;
 use crate::fmt;
-use crate::marker::PhantomData;
 use crate::vec;
 
 /// One-time global initialization.
@@ -27,9 +26,11 @@ pub fn args() -> Args {
 
 pub struct Args {
     iter: vec::IntoIter<OsString>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl fmt::Debug for Args {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.iter.as_slice().fmt(f)
@@ -77,7 +78,6 @@ fn next_back(&mut self) -> Option<OsString> {
 mod imp {
     use super::Args;
     use crate::ffi::{CStr, OsString};
-    use crate::marker::PhantomData;
     use crate::os::unix::prelude::*;
     use crate::ptr;
     use crate::sync::atomic::{AtomicIsize, AtomicPtr, Ordering};
@@ -134,7 +134,7 @@ pub unsafe fn cleanup() {
     }
 
     pub fn args() -> Args {
-        Args { iter: clone().into_iter(), _dont_send_or_sync_me: PhantomData }
+        Args { iter: clone().into_iter() }
     }
 
     fn clone() -> Vec<OsString> {
@@ -156,7 +156,6 @@ fn clone() -> Vec<OsString> {
 mod imp {
     use super::Args;
     use crate::ffi::CStr;
-    use crate::marker::PhantomData;
 
     pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
 
@@ -181,7 +180,7 @@ pub fn args() -> Args {
                 })
                 .collect::<Vec<_>>()
         };
-        Args { iter: vec.into_iter(), _dont_send_or_sync_me: PhantomData }
+        Args { iter: vec.into_iter() }
     }
 
     // As _NSGetArgc and _NSGetArgv aren't mentioned in iOS docs
@@ -248,6 +247,6 @@ pub fn args() -> Args {
             }
         }
 
-        Args { iter: res.into_iter(), _dont_send_or_sync_me: PhantomData }
+        Args { iter: res.into_iter() }
     }
 }

library/std/src/sys/unix/os.rs

@@ -12,7 +12,6 @@
 use crate::fmt;
 use crate::io;
 use crate::iter;
-use crate::marker::PhantomData;
 use crate::mem;
 use crate::memchr;
 use crate::path::{self, PathBuf};
@@ -460,9 +459,11 @@ pub fn current_exe() -> io::Result<PathBuf> {
 
 pub struct Env {
     iter: vec::IntoIter<(OsString, OsString)>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
+impl !Send for Env {}
+impl !Sync for Env {}
+
 impl Iterator for Env {
     type Item = (OsString, OsString);
     fn next(&mut self) -> Option<(OsString, OsString)> {
@@ -510,7 +511,7 @@ pub fn env() -> Env {
                 environ = environ.add(1);
             }
         }
-        return Env { iter: result.into_iter(), _dont_send_or_sync_me: PhantomData };
+        return Env { iter: result.into_iter() };
     }
 
     fn parse(input: &[u8]) -> Option<(OsString, OsString)> {

library/std/src/sys/wasi/args.rs

@@ -2,7 +2,6 @@
 
 use crate::ffi::{CStr, OsStr, OsString};
 use crate::fmt;
-use crate::marker::PhantomData;
 use crate::os::wasi::ffi::OsStrExt;
 use crate::vec;
 
@@ -12,15 +11,14 @@ pub unsafe fn cleanup() {}
 
 pub struct Args {
     iter: vec::IntoIter<OsString>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 /// Returns the command line arguments
 pub fn args() -> Args {
-    Args {
-        iter: maybe_args().unwrap_or(Vec::new()).into_iter(),
-        _dont_send_or_sync_me: PhantomData,
-    }
+    Args { iter: maybe_args().unwrap_or(Vec::new()).into_iter() }
 }
 
 fn maybe_args() -> Option<Vec<OsString>> {

library/std/src/sys/wasi/os.rs

@@ -129,9 +129,11 @@ pub fn current_exe() -> io::Result<PathBuf> {
 }
 pub struct Env {
     iter: vec::IntoIter<(OsString, OsString)>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
+impl !Send for Env {}
+impl !Sync for Env {}
+
 impl Iterator for Env {
     type Item = (OsString, OsString);
     fn next(&mut self) -> Option<(OsString, OsString)> {
@@ -155,7 +157,7 @@ pub fn env() -> Env {
                 environ = environ.add(1);
             }
         }
-        return Env { iter: result.into_iter(), _dont_send_or_sync_me: PhantomData };
+        return Env { iter: result.into_iter() };
     }
 
     // See src/libstd/sys/unix/os.rs, same as that

library/std/src/sys/wasm/args.rs

 use crate::ffi::OsString;
 use crate::fmt;
-use crate::marker::PhantomData;
 use crate::vec;
 
 pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
@@ -10,14 +9,16 @@ pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
 pub unsafe fn cleanup() {}
 
 pub fn args() -> Args {
-    Args { iter: Vec::new().into_iter(), _dont_send_or_sync_me: PhantomData }
+    Args { iter: Vec::new().into_iter() }
 }
 
 pub struct Args {
     iter: vec::IntoIter<OsString>,
-    _dont_send_or_sync_me: PhantomData<*mut ()>,
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl fmt::Debug for Args {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.iter.as_slice().fmt(f)