fix Issue 4020: problem reformatting block comments (#4071)

* add failing test

* fix

* remove source test file

Author: ahl

rustfmt-core/rustfmt-lib/src/comment.rs

@@ -92,8 +92,9 @@ impl<'a> CommentStyle<'a> {
             | CommentStyle::TripleSlash
             | CommentStyle::Custom(..)
             | CommentStyle::Doc => "",
-            CommentStyle::DoubleBullet => " **/",
-            CommentStyle::SingleBullet | CommentStyle::Exclamation => " */",
+            CommentStyle::SingleBullet | CommentStyle::DoubleBullet | CommentStyle::Exclamation => {
+                " */"
+            }
         }
     }
 
@@ -102,8 +103,9 @@ impl<'a> CommentStyle<'a> {
             CommentStyle::DoubleSlash => "// ",
             CommentStyle::TripleSlash => "/// ",
             CommentStyle::Doc => "//! ",
-            CommentStyle::SingleBullet | CommentStyle::Exclamation => " * ",
-            CommentStyle::DoubleBullet => " ** ",
+            CommentStyle::SingleBullet | CommentStyle::DoubleBullet | CommentStyle::Exclamation => {
+                " * "
+            }
             CommentStyle::Custom(opener) => opener,
         }
     }

rustfmt-core/rustfmt-lib/tests/target/issue-4020.rs

@@ -0,0 +1,9 @@
+// rustfmt-wrap_comments: true
+
+/** foobar */
+const foo1: u32 = 0;
+
+/**
+ * foobar
+ */
+const foo2: u32 = 0;