From a19dfb573d18c8b937c159cda24a3bb40ca5082d Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 12 Jun 2020 14:01:47 +0200
Subject: [PATCH 1/2] Create new E0763 error code for unterminated byte
 constant

---
 src/librustc_error_codes/error_codes.rs       |  1 +
 src/librustc_error_codes/error_codes/E0763.md | 13 +++++++++++++
 src/librustc_parse/lexer/mod.rs               | 11 +++++++++--
 3 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 src/librustc_error_codes/error_codes/E0763.md

diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs
index 3fb5e04efc922..1d6a579bdff32 100644
--- a/src/librustc_error_codes/error_codes.rs
+++ b/src/librustc_error_codes/error_codes.rs
@@ -442,6 +442,7 @@ E0758: include_str!("./error_codes/E0758.md"),
 E0760: include_str!("./error_codes/E0760.md"),
 E0761: include_str!("./error_codes/E0761.md"),
 E0762: include_str!("./error_codes/E0762.md"),
+E0763: include_str!("./error_codes/E0763.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/src/librustc_error_codes/error_codes/E0763.md b/src/librustc_error_codes/error_codes/E0763.md
new file mode 100644
index 0000000000000..095b779f3e78a
--- /dev/null
+++ b/src/librustc_error_codes/error_codes/E0763.md
@@ -0,0 +1,13 @@
+A byte constant wasn't correctly ended.
+
+Erroneous code example:
+
+```compile_fail,E0763
+let c = b'a; // error!
+```
+
+To fix this error, add the missing quote:
+
+```
+let c = b'a'; // ok!
+```
diff --git a/src/librustc_parse/lexer/mod.rs b/src/librustc_parse/lexer/mod.rs
index 84b3335a0f628..2e3cf4e746ae9 100644
--- a/src/librustc_parse/lexer/mod.rs
+++ b/src/librustc_parse/lexer/mod.rs
@@ -339,8 +339,15 @@ impl<'a> StringReader<'a> {
             }
             rustc_lexer::LiteralKind::Byte { terminated } => {
                 if !terminated {
-                    self.fatal_span_(start + BytePos(1), suffix_start, "unterminated byte constant")
-                        .raise()
+                    self.sess
+                        .span_diagnostic
+                        .struct_span_fatal_with_code(
+                            self.mk_sp(start + BytePos(1), suffix_start),
+                            "unterminated byte constant",
+                            error_code!(E0763),
+                        )
+                        .emit();
+                    FatalError.raise();
                 }
                 (token::Byte, Mode::Byte, 2, 1) // b' '
             }

From bad252c9faebf55565091f50bad784a0a3f1e756 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 12 Jun 2020 14:01:53 +0200
Subject: [PATCH 2/2] Update ui tests

---
 src/test/ui/parser/byte-literals.rs     | 2 +-
 src/test/ui/parser/byte-literals.stderr | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/test/ui/parser/byte-literals.rs b/src/test/ui/parser/byte-literals.rs
index dadf3971220f7..9683a83e72095 100644
--- a/src/test/ui/parser/byte-literals.rs
+++ b/src/test/ui/parser/byte-literals.rs
@@ -8,5 +8,5 @@ pub fn main() {
     b'	';  //~ ERROR byte constant must be escaped
     b''';  //~ ERROR byte constant must be escaped
     b'é';  //~ ERROR byte constant must be ASCII
-    b'a  //~ ERROR unterminated byte constant
+    b'a  //~ ERROR unterminated byte constant [E0763]
 }
diff --git a/src/test/ui/parser/byte-literals.stderr b/src/test/ui/parser/byte-literals.stderr
index 53d50af88d33b..7bbdc07cd835f 100644
--- a/src/test/ui/parser/byte-literals.stderr
+++ b/src/test/ui/parser/byte-literals.stderr
@@ -34,7 +34,7 @@ error: byte constant must be ASCII. Use a \xHH escape for a non-ASCII byte
 LL |     b'é';
    |       ^
 
-error: unterminated byte constant
+error[E0763]: unterminated byte constant
   --> $DIR/byte-literals.rs:11:6
    |
 LL |     b'a
@@ -42,3 +42,4 @@ LL |     b'a
 
 error: aborting due to 7 previous errors
 
+For more information about this error, try `rustc --explain E0763`.