Rollup merge of #50421 - kennytm:fix-50415-ice-when-returning-range-inclusive-from-closure, r=michaelwoerister

Fix ICE when using a..=b in a closure.

Fix #50415.

src/test/run-pass/issue-50415.rs

@@ -0,0 +1,27 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    // -------- Simplified test case --------
+
+    let _ = || 0..=1;
+
+    // -------- Original test case --------
+
+    let full_length = 1024;
+    let range = {
+        // do some stuff, omit here
+        None
+    };
+
+    let range = range.map(|(s, t)| s..=t).unwrap_or(0..=(full_length-1));
+
+    assert_eq!(range, 0..=1023);
+}