From 083c2f6ceb82b75ec04c73f2b39a414985fd9a92 Mon Sep 17 00:00:00 2001
From: David Wood <david@davidtw.co>
Date: Sun, 12 Jul 2020 18:22:09 +0100
Subject: [PATCH] pprust: support multiline comments within lines

This commit adds support to rustc_ast_pretty for multiline comments that
start and end within a line of source code.

Signed-off-by: David Wood <david@davidtw.co>
---
 src/librustc_ast_pretty/pprust.rs | 15 ++++++++++++--
 src/test/pretty/issue-73626.rs    | 34 +++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 src/test/pretty/issue-73626.rs

diff --git a/src/librustc_ast_pretty/pprust.rs b/src/librustc_ast_pretty/pprust.rs
index 2d803262f79e1..c33cae57872ac 100644
--- a/src/librustc_ast_pretty/pprust.rs
+++ b/src/librustc_ast_pretty/pprust.rs
@@ -450,9 +450,20 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     fn print_comment(&mut self, cmnt: &comments::Comment) {
         match cmnt.style {
             comments::Mixed => {
-                assert_eq!(cmnt.lines.len(), 1);
                 self.zerobreak();
-                self.word(cmnt.lines[0].clone());
+                if let Some((last, lines)) = cmnt.lines.split_last() {
+                    self.ibox(0);
+
+                    for line in lines {
+                        self.word(line.clone());
+                        self.hardbreak()
+                    }
+
+                    self.word(last.clone());
+                    self.space();
+
+                    self.end();
+                }
                 self.zerobreak()
             }
             comments::Isolated => {
diff --git a/src/test/pretty/issue-73626.rs b/src/test/pretty/issue-73626.rs
new file mode 100644
index 0000000000000..a002f09be3b4e
--- /dev/null
+++ b/src/test/pretty/issue-73626.rs
@@ -0,0 +1,34 @@
+fn main(/*
+    ---
+*/) {
+    let x /* this is one line */ = 3;
+
+    let x /*
+           * this
+           * is
+           * multiple
+           * lines
+           */ = 3;
+
+    let x = /*
+           * this
+           * is
+           * multiple
+           * lines
+           * after
+           * the
+           * =
+           */ 3;
+
+    let x /*
+           * this
+           * is
+           * multiple
+           * lines
+           * including
+           * a
+
+           * blank
+           * line
+           */ = 3;
+}