Upgrade Emscripten targets to use upstream LLVM backend

 - Compatible with Emscripten 1.38.46-upstream or later upstream.
 - Refactors the Emscripten target spec to share code with other wasm
   targets.
 - Replaces the old incorrect wasm32 C call ABI with the correct one,
   preserving the old one as wasm32_bindgen_compat for wasm-bindgen
   compatibility.
 - Updates the varargs ABI used by Emscripten and deletes the old one.
 - Removes the obsolete wasm32-experimental-emscripten target.
 - Uses EMCC_CFLAGS on CI to avoid the timeout problems with #63649.

3 files changed, 13 insertions, 9 deletions

diff --git a/src/liballoc/tests/binary_heap.rs b/src/liballoc/tests/binary_heap.rs
index 0685fa943c0..b8c720264d0 100644
--- a/src/liballoc/tests/binary_heap.rs
+++ b/src/liballoc/tests/binary_heap.rs
@@ -1,10 +1,5 @@
-use std::cmp;
 use std::collections::BinaryHeap;
 use std::collections::binary_heap::{Drain, PeekMut};
-use std::panic::{self, AssertUnwindSafe};
-use std::sync::atomic::{AtomicUsize, Ordering};
-
-use rand::{thread_rng, seq::SliceRandom};
 
 #[test]
 fn test_iterator() {
@@ -281,9 +276,15 @@ fn assert_covariance() {
 // even if the order may not be correct.
 //
 // Destructors must be called exactly once per element.
+// FIXME: re-enable emscripten once it can unwind again
 #[test]
-#[cfg(not(miri))] // Miri does not support catching panics
+#[cfg(not(any(miri, target_os = "emscripten")))] // Miri does not support catching panics
 fn panic_safe() {
+    use std::cmp;
+    use std::panic::{self, AssertUnwindSafe};
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    use rand::{thread_rng, seq::SliceRandom};
+
     static DROP_COUNTER: AtomicUsize = AtomicUsize::new(0);
 
     #[derive(Eq, PartialEq, Ord, Clone, Debug)]
diff --git a/src/liballoc/tests/str.rs b/src/liballoc/tests/str.rs
index 4332b2e90fd..cb73c7c179c 100644
--- a/src/liballoc/tests/str.rs
+++ b/src/liballoc/tests/str.rs
@@ -483,7 +483,7 @@ mod slice_index {
     }
 
     #[test]
-    #[cfg(not(target_arch = "asmjs"))] // hits an OOM
+    #[cfg(not(target_os = "emscripten"))] // hits an OOM
     #[cfg(not(miri))] // Miri is too slow
     fn simple_big() {
         fn a_million_letter_x() -> String {
diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs
index 98d013dfa2b..80537217697 100644
--- a/src/liballoc/tests/vec.rs
+++ b/src/liballoc/tests/vec.rs
@@ -944,8 +944,10 @@ fn drain_filter_complex() {
     }
 }
 
+// Miri does not support catching panics
+// FIXME: re-enable emscripten once it can unwind again
 #[test]
-#[cfg(not(miri))] // Miri does not support catching panics
+#[cfg(not(any(miri, target_os = "emscripten")))]
 fn drain_filter_consumed_panic() {
     use std::rc::Rc;
     use std::sync::Mutex;
@@ -995,8 +997,9 @@ fn drain_filter_consumed_panic() {
     }
 }
 
+// FIXME: Re-enable emscripten once it can catch panics
 #[test]
-#[cfg(not(miri))] // Miri does not support catching panics
+#[cfg(not(any(miri, target_os = "emscripten")))] // Miri does not support catching panics
 fn drain_filter_unconsumed_panic() {
     use std::rc::Rc;
     use std::sync::Mutex;