[clang] [Clang] Propagate elide safe context through [[clang::coro_must_await]] (PR #108474)

[Yuxuan Chen via cfe-commits]

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@@ -84,4 +84,35 @@ Task<int> nonelidable() {
   co_return 1;
 }
 
+// CHECK-LABEL: define{{.*}} @_Z8addTasksO4TaskIiES1_{{.*}} {
+Task<int> addTasks([[clang::coro_must_await]] Task<int> &&t1, Task<int> &&t2) {
+  int i1 = co_await t1;
+  int i2 = co_await t2;
+  co_return i1 + i2;
+}
+
+// CHECK-LABEL: define{{.*}} @_Z10returnSamei{{.*}} {
+Task<int> returnSame(int i) {
+  co_return i;
+}
+
+// CHECK-LABEL: define{{.*}} @_Z21elidableWithMustAwaitv{{.*}} {
+Task<int> elidableWithMustAwait() {
+  // CHECK: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 2) #[[ELIDE_SAFE]]
+  // CHECK-NOT: call void @_Z10returnSamei(ptr {{.*}}, i32 noundef 3) #[[ELIDE_SAFE]]
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yuxuanchen1997 wrote:

Just letting you know that `$` at the end is asking the directive to literally check for a dollar sign. `{{$}}` at the end seemed to work fine. 

https://github.com/llvm/llvm-project/pull/108474