Auto merge of #44112 - alexcrichton:thread-join, r=sfackler

std: Handle OS errors when joining threads

Also add to the documentation that the `join` method can panic.

cc #34971
cc #43539

3 files changed, 8 insertions, 2 deletions

diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index 15747746611..40f1d6a6db1 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -168,7 +168,8 @@ impl Thread {
         unsafe {
             let ret = libc::pthread_join(self.id, ptr::null_mut());
             mem::forget(self);
-            debug_assert_eq!(ret, 0);
+            assert!(ret == 0,
+                    "failed to join thread: {}", io::Error::from_raw_os_error(ret));
         }
     }
 
diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index ba54ca6ea18..7dfcc996e18 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -273,6 +273,7 @@ pub const FILE_END: DWORD = 2;
 
 pub const WAIT_OBJECT_0: DWORD = 0x00000000;
 pub const WAIT_TIMEOUT: DWORD = 258;
+pub const WAIT_FAILED: DWORD = 0xFFFFFFFF;
 
 #[cfg(target_env = "msvc")]
 pub const MAX_SYM_NAME: usize = 2000;
diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index 5a376a867ee..2cdd86e88b0 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -61,7 +61,11 @@ impl Thread {
     }
 
     pub fn join(self) {
-        unsafe { c::WaitForSingleObject(self.handle.raw(), c::INFINITE); }
+        let rc = unsafe { c::WaitForSingleObject(self.handle.raw(), c::INFINITE) };
+        if rc == c::WAIT_FAILED {
+            panic!("failed to join on thread: {}",
+                   io::Error::last_os_error());
+        }
     }
 
     pub fn yield_now() {