From e08944fdafac547aecc1a94e44cc978a202eec86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 13 Dec 2019 15:27:55 -0800
Subject: [PATCH] Do not ICE on unnamed future

---
 src/librustc/hir/map/mod.rs                   | 13 +++++++---
 src/librustc/traits/error_reporting.rs        |  2 +-
 .../async-await/issue-67252-unnamed-future.rs | 24 +++++++++++++++++++
 .../issue-67252-unnamed-future.stderr         | 22 +++++++++++++++++
 4 files changed, 57 insertions(+), 4 deletions(-)
 create mode 100644 src/test/ui/async-await/issue-67252-unnamed-future.rs
 create mode 100644 src/test/ui/async-await/issue-67252-unnamed-future.stderr

diff --git a/src/librustc/hir/map/mod.rs b/src/librustc/hir/map/mod.rs
index 5bf5a93ad0102..69e772697f846 100644
--- a/src/librustc/hir/map/mod.rs
+++ b/src/librustc/hir/map/mod.rs
@@ -1016,8 +1016,8 @@ impl<'hir> Map<'hir> {
         }
     }
 
-    pub fn name(&self, id: HirId) -> Name {
-        match self.get(id) {
+    pub fn opt_name(&self, id: HirId) -> Option<Name> {
+        Some(match self.get(id) {
             Node::Item(i) => i.ident.name,
             Node::ForeignItem(fi) => fi.ident.name,
             Node::ImplItem(ii) => ii.ident.name,
@@ -1028,7 +1028,14 @@ impl<'hir> Map<'hir> {
             Node::GenericParam(param) => param.name.ident().name,
             Node::Binding(&Pat { kind: PatKind::Binding(_, _, l, _), .. }) => l.name,
             Node::Ctor(..) => self.name(self.get_parent_item(id)),
-            _ => bug!("no name for {}", self.node_to_string(id))
+            _ => return None,
+        })
+    }
+
+    pub fn name(&self, id: HirId) -> Name {
+        match self.opt_name(id) {
+            Some(name) => name,
+            None => bug!("no name for {}", self.node_to_string(id)),
         }
     }
 
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index 6a111895b5637..1a92d1eb8c5d3 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -2353,7 +2353,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             let message = if let Some(name) = last_generator
                 .and_then(|generator_did| self.tcx.parent(generator_did))
                 .and_then(|parent_did| self.tcx.hir().as_local_hir_id(parent_did))
-                .map(|parent_hir_id| self.tcx.hir().name(parent_hir_id))
+                .and_then(|parent_hir_id| self.tcx.hir().opt_name(parent_hir_id))
             {
                 format!("future returned by `{}` is not {}", name, trait_name)
             } else {
diff --git a/src/test/ui/async-await/issue-67252-unnamed-future.rs b/src/test/ui/async-await/issue-67252-unnamed-future.rs
new file mode 100644
index 0000000000000..1a7ff613341ec
--- /dev/null
+++ b/src/test/ui/async-await/issue-67252-unnamed-future.rs
@@ -0,0 +1,24 @@
+// edition:2018
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+fn spawn<T: Send>(_: T) {}
+
+pub struct AFuture;
+impl Future for AFuture{
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<()> {
+        unimplemented!()
+    }
+}
+
+async fn foo() {
+    spawn(async { //~ ERROR future cannot be sent between threads safely
+        let _a = std::ptr::null_mut::<()>(); // `*mut ()` is not `Send`
+        AFuture.await;
+    });
+}
+
+fn main() {}
diff --git a/src/test/ui/async-await/issue-67252-unnamed-future.stderr b/src/test/ui/async-await/issue-67252-unnamed-future.stderr
new file mode 100644
index 0000000000000..24aedeb96597a
--- /dev/null
+++ b/src/test/ui/async-await/issue-67252-unnamed-future.stderr
@@ -0,0 +1,22 @@
+error: future cannot be sent between threads safely
+  --> $DIR/issue-67252-unnamed-future.rs:18:5
+   |
+LL | fn spawn<T: Send>(_: T) {}
+   |    -----    ---- required by this bound in `spawn`
+...
+LL |     spawn(async {
+   |     ^^^^^ future is not `Send`
+   |
+   = help: within `impl std::future::Future`, the trait `std::marker::Send` is not implemented for `*mut ()`
+note: future is not `Send` as this value is used across an await
+  --> $DIR/issue-67252-unnamed-future.rs:20:9
+   |
+LL |         let _a = std::ptr::null_mut::<()>(); // `*mut ()` is not `Send`
+   |             -- has type `*mut ()`
+LL |         AFuture.await;
+   |         ^^^^^^^^^^^^^ await occurs here, with `_a` maybe used later
+LL |     });
+   |     - `_a` is later dropped here
+
+error: aborting due to previous error
+