diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 196f7879980e8..51f0c1d7047c9 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -3121,9 +3121,9 @@ impl<'a> LoweringContext<'a> {
             }
             // Desugar `<start>..=<end>` to `std::ops::RangeInclusive::new(<start>, <end>)`
             ExprKind::Range(Some(ref e1), Some(ref e2), RangeLimits::Closed) => {
-                // FIXME: Use head_sp directly after RangeInclusive::new() is stabilized in stage0.
+                // FIXME: Use e.span directly after RangeInclusive::new() is stabilized in stage0.
                 let span = self.allow_internal_unstable(CompilerDesugaringKind::DotFill, e.span);
-                let id = self.lower_node_id(e.id);
+                let id = self.next_id();
                 let e1 = self.lower_expr(e1);
                 let e2 = self.lower_expr(e2);
                 let ty_path = P(self.std_path(span, &["ops", "RangeInclusive"], false));
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index 13f8bb9a31831..b5461d61dd4f6 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -1252,10 +1252,7 @@ impl LitKind {
 
         match *self {
             LitKind::Str(string, ast::StrStyle::Cooked) => {
-                let mut escaped = String::new();
-                for ch in string.as_str().chars() {
-                    escaped.extend(ch.escape_unicode());
-                }
+                let escaped = string.as_str().escape_default();
                 Token::Literal(token::Lit::Str_(Symbol::intern(&escaped)), None)
             }
             LitKind::Str(string, ast::StrStyle::Raw(n)) => {
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 870ce1926ade4..f148aaf7267ee 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -25,6 +25,7 @@
 #![feature(non_exhaustive)]
 #![feature(const_atomic_usize_new)]
 #![feature(rustc_attrs)]
+#![feature(str_escape)]
 
 #![recursion_limit="256"]
 
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index ff09c6aa2f006..f252020bc3169 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -298,14 +298,10 @@ pub fn char_lit(lit: &str, diag: Option<(Span, &Handler)>) -> (char, isize) {
     }
 }
 
-pub fn escape_default(s: &str) -> String {
-    s.chars().map(char::escape_default).flat_map(|x| x).collect()
-}
-
 /// Parse a string representing a string literal into its final form. Does
 /// unescaping.
 pub fn str_lit(lit: &str, diag: Option<(Span, &Handler)>) -> String {
-    debug!("parse_str_lit: given {}", escape_default(lit));
+    debug!("str_lit: given {}", lit.escape_default());
     let mut res = String::with_capacity(lit.len());
 
     let error = |i| format!("lexer should have rejected {} at {}", lit, i);
@@ -374,7 +370,7 @@ pub fn str_lit(lit: &str, diag: Option<(Span, &Handler)>) -> String {
 /// Parse a string representing a raw string literal into its final form. The
 /// only operation this does is convert embedded CRLF into a single LF.
 pub fn raw_str_lit(lit: &str) -> String {
-    debug!("raw_str_lit: given {}", escape_default(lit));
+    debug!("raw_str_lit: given {}", lit.escape_default());
     let mut res = String::with_capacity(lit.len());
 
     let mut chars = lit.chars().peekable();
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 88860df10e2c3..27c5a14ff0e8b 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -656,7 +656,7 @@ pub trait PrintState<'a> {
                     style: ast::StrStyle) -> io::Result<()> {
         let st = match style {
             ast::StrStyle::Cooked => {
-                (format!("\"{}\"", parse::escape_default(st)))
+                (format!("\"{}\"", st.escape_default()))
             }
             ast::StrStyle::Raw(n) => {
                 (format!("r{delim}\"{string}\"{delim}",
diff --git a/src/test/run-pass/issue-50415.rs b/src/test/run-pass/issue-50415.rs
new file mode 100644
index 0000000000000..aa493ce032130
--- /dev/null
+++ b/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);
+}