From 647bf96b796a56e01557c14731719ab93f39063f Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Mon, 22 Jul 2019 12:59:18 +0300
Subject: [PATCH] fix lexing of comments with many \r

closes #62863
---
 src/libsyntax/parse/lexer/mod.rs              |  2 +-
 ...several-carriage-returns-in-doc-comment.rs | 10 ++++++++++
 ...ral-carriage-returns-in-doc-comment.stderr | 20 +++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/parser/several-carriage-returns-in-doc-comment.rs
 create mode 100644 src/test/ui/parser/several-carriage-returns-in-doc-comment.stderr

diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index 317c49c7d3543..bfefd9adbfe8f 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -226,7 +226,7 @@ impl<'a> StringReader<'a> {
                     loop {
                         idx = match string[idx..].find('\r') {
                             None => break,
-                            Some(it) => it + 1
+                            Some(it) => idx + it + 1
                         };
                         if string[idx..].chars().next() != Some('\n') {
                             self.err_span_(start + BytePos(idx as u32 - 1),
diff --git a/src/test/ui/parser/several-carriage-returns-in-doc-comment.rs b/src/test/ui/parser/several-carriage-returns-in-doc-comment.rs
new file mode 100644
index 0000000000000..ee14c55d292a7
--- /dev/null
+++ b/src/test/ui/parser/several-carriage-returns-in-doc-comment.rs
@@ -0,0 +1,10 @@
+// Issue #62863
+// ignore-tidy-cr
+
+// Note: if you see ^M in this file, that's how your editor renders literal `\r`
+
+/// This do
c comment contains 
three isolated `\r`
 symbols
+//~^ ERROR bare CR not allowed in doc-comment
+//~| ERROR bare CR not allowed in doc-comment
+//~| ERROR bare CR not allowed in doc-comment
+fn main() {}
diff --git a/src/test/ui/parser/several-carriage-returns-in-doc-comment.stderr b/src/test/ui/parser/several-carriage-returns-in-doc-comment.stderr
new file mode 100644
index 0000000000000..07066fc22e6cd
--- /dev/null
+++ b/src/test/ui/parser/several-carriage-returns-in-doc-comment.stderr
@@ -0,0 +1,20 @@
+error: bare CR not allowed in doc-comment
+  --> $DIR/several-carriage-returns-in-doc-comment.rs:6:12
+   |
+LL | /// This do
c comment contains 
three isolated `\r`
 symbols
+   |            ^
+
+error: bare CR not allowed in doc-comment
+  --> $DIR/several-carriage-returns-in-doc-comment.rs:6:32
+   |
+LL | /// This do
c comment contains 
three isolated `\r`
 symbols
+   |                               ^
+
+error: bare CR not allowed in doc-comment
+  --> $DIR/several-carriage-returns-in-doc-comment.rs:6:52
+   |
+LL | /// This do
c comment contains 
three isolated `\r`
 symbols
+   |                                                  ^
+
+error: aborting due to 3 previous errors
+