Windows: set main thread name without reencoding

Author: ChrisDenton

library/std/src/sys/pal/windows/mod.rs

@@ -60,7 +60,7 @@ pub unsafe fn init(_argc: isize, _argv: *const *const u8, _sigpipe: u8) {
 
     // Normally, `thread::spawn` will call `Thread::set_name` but since this thread already
     // exists, we have to call it ourselves.
-    thread::Thread::set_name(&c"main");
+    thread::Thread::set_name_wide(&['m' as u16, 'a' as u16, 'i' as u16, 'n' as u16, 0]);
 }
 
 // SAFETY: must be called only once during runtime cleanup.

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

@@ -59,13 +59,17 @@ impl Thread {
     pub fn set_name(name: &CStr) {
         if let Ok(utf8) = name.to_str() {
             if let Ok(utf16) = to_u16s(utf8) {
-                unsafe {
-                    c::SetThreadDescription(c::GetCurrentThread(), utf16.as_ptr());
-                };
+                Self::set_name_wide(&utf16)
             };
         };
     }
 
+    pub fn set_name_wide(name: &[u16]) {
+        unsafe {
+            c::SetThreadDescription(c::GetCurrentThread(), name.as_ptr());
+        };
+    }
+
     pub fn join(self) {
         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
         if rc == c::WAIT_FAILED {