From 7d61484b469aeb9db9c4d7a69c3bf1f24882d183 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Wed, 13 Nov 2019 15:22:45 -0800
Subject: [PATCH] Do not ICE in `if` without `else` in `async fn`

---
 src/librustc_typeck/check/generator_interior.rs  | 10 ++++++++--
 .../async-await/issue-66387-if-without-else.rs   |  8 ++++++++
 .../issue-66387-if-without-else.stderr           | 16 ++++++++++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 src/test/ui/async-await/issue-66387-if-without-else.rs
 create mode 100644 src/test/ui/async-await/issue-66387-if-without-else.stderr

diff --git a/src/librustc_typeck/check/generator_interior.rs b/src/librustc_typeck/check/generator_interior.rs
index ff9c945eec45..6e254122c010 100644
--- a/src/librustc_typeck/check/generator_interior.rs
+++ b/src/librustc_typeck/check/generator_interior.rs
@@ -244,7 +244,13 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
         // can be reborrowed without needing to spill to a temporary.
         // If this were not the case, then we could conceivably have
         // to create intermediate temporaries.)
-        let ty = self.fcx.tables.borrow().expr_ty(expr);
-        self.record(ty, scope, Some(expr), expr.span);
+        //
+        // The type table might not have invormation for this expression
+        // if it is in a malformed scope. (#66387)
+        if let Some(ty) = self.fcx.tables.borrow().expr_ty_opt(expr) {
+            self.record(ty, scope, Some(expr), expr.span);
+        } else {
+            self.fcx.tcx.sess.delay_span_bug(expr.span, "no type for node");
+        }
     }
 }
diff --git a/src/test/ui/async-await/issue-66387-if-without-else.rs b/src/test/ui/async-await/issue-66387-if-without-else.rs
new file mode 100644
index 000000000000..3602b09c0ece
--- /dev/null
+++ b/src/test/ui/async-await/issue-66387-if-without-else.rs
@@ -0,0 +1,8 @@
+// edition:2018
+async fn f() -> i32 {
+    if true { //~ ERROR if may be missing an else clause
+        return 0;
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/async-await/issue-66387-if-without-else.stderr b/src/test/ui/async-await/issue-66387-if-without-else.stderr
new file mode 100644
index 000000000000..32952059525a
--- /dev/null
+++ b/src/test/ui/async-await/issue-66387-if-without-else.stderr
@@ -0,0 +1,16 @@
+error[E0317]: if may be missing an else clause
+  --> $DIR/issue-66387-if-without-else.rs:3:5
+   |
+LL | /     if true {
+LL | |         return 0;
+LL | |     }
+   | |_____^ expected (), found i32
+   |
+   = note: expected type `()`
+              found type `i32`
+   = note: `if` expressions without `else` evaluate to `()`
+   = help: consider adding an `else` block that evaluates to the expected type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0317`.