rollup merge of #21920: vojtechkral/main-thread-name

Fixes #21911

src/libstd/sys/common/thread_info.rs

@@ -56,10 +56,6 @@ pub fn stack_guard() -> uint {
 
 pub fn set(stack_bounds: (uint, uint), stack_guard: uint, thread: Thread) {
     THREAD_INFO.with(|c| assert!(c.borrow().is_none()));
-    match thread.name() {
-        Some(name) => unsafe { ::sys::thread::set_name(name); },
-        None => {}
-    }
     THREAD_INFO.with(move |c| *c.borrow_mut() = Some(ThreadInfo{
         stack_bounds: stack_bounds,
         stack_guard: stack_guard,

src/libstd/thread.rs

@@ -156,6 +156,7 @@ use ops::{Drop, FnOnce};
 use option::Option::{self, Some, None};
 use result::Result::{Err, Ok};
 use sync::{Mutex, Condvar, Arc};
+use str::Str;
 use string::String;
 use rt::{self, unwind};
 use old_io::{Writer, stdio};
@@ -280,6 +281,10 @@ impl Builder {
             unsafe {
                 stack::record_os_managed_stack_bounds(my_stack_bottom, my_stack_top);
             }
+            match their_thread.name() {
+                Some(name) => unsafe { imp::set_name(name.as_slice()); },
+                None => {}
+            }
             thread_info::set(
                 (my_stack_bottom, my_stack_top),
                 unsafe { imp::guard::current() },