Auto merge of #32001 - Manishearth:rollup, r=Manishearth

- Successful merges: #31919, #31982, #31985, #31989, #31999
- Failed merges:

2 files changed, 7 insertions, 1 deletions

diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 8fb49a1be4e..a1144a964fd 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -23,7 +23,7 @@ fn main() {
 
     let target = env::var("TARGET").unwrap();
     let host = env::var("HOST").unwrap();
-    if !target.contains("apple") && !target.contains("msvc") {
+    if !target.contains("apple") && !target.contains("msvc") && !target.contains("emscripten"){
         build_libbacktrace(&host, &target);
     }
 
diff --git a/src/libstd/sync/mpsc/mod.rs b/src/libstd/sync/mpsc/mod.rs
index fadca390986..dbcc2bc95bc 100644
--- a/src/libstd/sync/mpsc/mod.rs
+++ b/src/libstd/sync/mpsc/mod.rs
@@ -299,6 +299,9 @@ pub struct Receiver<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<T: Send> Send for Receiver<T> { }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> !Sync for Receiver<T> { }
+
 /// An iterator over messages on a receiver, this iterator will block
 /// whenever `next` is called, waiting for a new message, and `None` will be
 /// returned when the corresponding channel has hung up.
@@ -327,6 +330,9 @@ pub struct Sender<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<T: Send> Send for Sender<T> { }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> !Sync for Sender<T> { }
+
 /// The sending-half of Rust's synchronous channel type. This half can only be
 /// owned by one thread, but it can be cloned to send to other threads.
 #[stable(feature = "rust1", since = "1.0.0")]