From c7d9d89e9b160ff629ffe5725fd52dc4cbdcff44 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Wed, 1 Apr 2020 00:41:40 +0200
Subject: [PATCH] Hide `task_context` when lowering body

---
 src/librustc_ast_lowering/item.rs          |  2 +
 src/test/ui/async-await/issue-70594.rs     | 12 ++++++
 src/test/ui/async-await/issue-70594.stderr | 44 ++++++++++++++++++++++
 3 files changed, 58 insertions(+)
 create mode 100644 src/test/ui/async-await/issue-70594.rs
 create mode 100644 src/test/ui/async-await/issue-70594.stderr

diff --git a/src/librustc_ast_lowering/item.rs b/src/librustc_ast_lowering/item.rs
index b319ee76c819f..6005b607026fb 100644
--- a/src/librustc_ast_lowering/item.rs
+++ b/src/librustc_ast_lowering/item.rs
@@ -972,8 +972,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
         f: impl FnOnce(&mut Self) -> (&'hir [hir::Param<'hir>], hir::Expr<'hir>),
     ) -> hir::BodyId {
         let prev_gen_kind = self.generator_kind.take();
+        let task_context = self.task_context.take();
         let (parameters, result) = f(self);
         let body_id = self.record_body(parameters, result);
+        self.task_context = task_context;
         self.generator_kind = prev_gen_kind;
         body_id
     }
diff --git a/src/test/ui/async-await/issue-70594.rs b/src/test/ui/async-await/issue-70594.rs
new file mode 100644
index 0000000000000..e78231a68512d
--- /dev/null
+++ b/src/test/ui/async-await/issue-70594.rs
@@ -0,0 +1,12 @@
+// edition:2018
+
+async fn fun() {
+    [1; ().await];
+    //~^ error: `await` is only allowed inside `async` functions and blocks
+    //~| error: `.await` is not allowed in a `const`
+    //~| error: `loop` is not allowed in a `const`
+    //~| error: `.await` is not allowed in a `const`
+    //~| error: the trait bound `(): std::future::Future` is not satisfied
+}
+
+fn main() {}
diff --git a/src/test/ui/async-await/issue-70594.stderr b/src/test/ui/async-await/issue-70594.stderr
new file mode 100644
index 0000000000000..d2fa7e58f6a9b
--- /dev/null
+++ b/src/test/ui/async-await/issue-70594.stderr
@@ -0,0 +1,44 @@
+error[E0728]: `await` is only allowed inside `async` functions and blocks
+  --> $DIR/issue-70594.rs:4:9
+   |
+LL | async fn fun() {
+   |          --- this is not `async`
+LL |     [1; ().await];
+   |         ^^^^^^^^ only allowed inside `async` functions and blocks
+
+error[E0744]: `.await` is not allowed in a `const`
+  --> $DIR/issue-70594.rs:4:9
+   |
+LL |     [1; ().await];
+   |         ^^^^^^^^
+
+error[E0658]: `loop` is not allowed in a `const`
+  --> $DIR/issue-70594.rs:4:9
+   |
+LL |     [1; ().await];
+   |         ^^^^^^^^
+   |
+   = note: see issue #52000 <https://github.com/rust-lang/rust/issues/52000> for more information
+   = help: add `#![feature(const_loop)]` to the crate attributes to enable
+
+error[E0744]: `.await` is not allowed in a `const`
+  --> $DIR/issue-70594.rs:4:9
+   |
+LL |     [1; ().await];
+   |         ^^^^^^^^
+
+error[E0277]: the trait bound `(): std::future::Future` is not satisfied
+  --> $DIR/issue-70594.rs:4:9
+   |
+LL |     [1; ().await];
+   |         ^^^^^^^^ the trait `std::future::Future` is not implemented for `()`
+   | 
+  ::: $SRC_DIR/libcore/future/mod.rs:LL:COL
+   |
+LL |     F: Future,
+   |        ------ required by this bound in `std::future::poll_with_context`
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0277, E0658, E0728, E0744.
+For more information about an error, try `rustc --explain E0277`.