Rollup merge of rust-lang#84655 - CDirkx:wasm, r=m-ou-se

Cleanup of `wasm`

Some more cleanup of `sys`, this time `wasm`

- Reuse `unsupported::args` (functionally equivalent implementation, just an empty iterator).
- Split out `atomics` implementation of `wasm::thread`, the non-`atomics` implementation is reused from `unsupported`.
- Move all of the `atomics` code to a separate directory `wasm/atomics`.

```@rustbot``` label: +T-libs-impl
r? ```@m-ou-se```

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

@@ -1,4 +1,5 @@
 use crate::ffi::OsString;
+use crate::fmt;
 
 pub struct Args {}
 

library/std/src/sys/wasm/thread.rs → library/std/src/sys/wasm/atomics/thread.rs

@@ -13,20 +13,10 @@ impl Thread {
         unsupported()
     }
 
-    pub fn yield_now() {
-        // do nothing
-    }
+    pub fn yield_now() {}
 
-    pub fn set_name(_name: &CStr) {
-        // nope
-    }
+    pub fn set_name(_name: &CStr) {}
 
-    #[cfg(not(target_feature = "atomics"))]
-    pub fn sleep(_dur: Duration) {
-        panic!("can't sleep");
-    }
-
-    #[cfg(target_feature = "atomics")]
     pub fn sleep(dur: Duration) {
         use crate::arch::wasm32;
         use crate::cmp;
@@ -46,9 +36,7 @@ impl Thread {
         }
     }
 
-    pub fn join(self) {
-        self.0
-    }
+    pub fn join(self) {}
 }
 
 pub mod guard {
@@ -61,11 +49,9 @@ pub mod guard {
     }
 }
 
-// This is only used by atomics primitives when the `atomics` feature is
-// enabled. In that mode we currently just use our own thread-local to store our
+// We currently just use our own thread-local to store our
 // current thread's ID, and then we lazily initialize it to something allocated
 // from a global counter.
-#[cfg(target_feature = "atomics")]
 pub fn my_id() -> u32 {
     use crate::sync::atomic::{AtomicU32, Ordering::SeqCst};
 

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

@@ -17,6 +17,7 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
 pub mod alloc;
+#[path = "../unsupported/args.rs"]
 pub mod args;
 #[path = "../unix/cmath.rs"]
 pub mod cmath;
@@ -37,7 +38,6 @@ pub mod pipe;
 pub mod process;
 #[path = "../unsupported/stdio.rs"]
 pub mod stdio;
-pub mod thread;
 #[path = "../unsupported/thread_local_dtor.rs"]
 pub mod thread_local_dtor;
 #[path = "../unsupported/thread_local_key.rs"]
@@ -49,21 +49,25 @@ pub use crate::sys_common::os_str_bytes as os_str;
 
 cfg_if::cfg_if! {
     if #[cfg(target_feature = "atomics")] {
-        #[path = "condvar_atomics.rs"]
+        #[path = "atomics/condvar.rs"]
         pub mod condvar;
-        #[path = "mutex_atomics.rs"]
+        #[path = "atomics/mutex.rs"]
         pub mod mutex;
-        #[path = "rwlock_atomics.rs"]
+        #[path = "atomics/rwlock.rs"]
         pub mod rwlock;
-        #[path = "futex_atomics.rs"]
+        #[path = "atomics/futex.rs"]
         pub mod futex;
+        #[path = "atomics/thread.rs"]
+        pub mod thread;
     } else {
         #[path = "../unsupported/condvar.rs"]
         pub mod condvar;
         #[path = "../unsupported/mutex.rs"]
         pub mod mutex;
         #[path = "../unsupported/rwlock.rs"]
         pub mod rwlock;
+        #[path = "../unsupported/thread.rs"]
+        pub mod thread;
     }
 }