[clang-format] Break non-trailing comments, try 2

Summary:
This patch enables `BreakableToken` to manage the formatting of non-trailing
block comments. It is a refinement of https://reviews.llvm.org/D37007.
We discovered that the optimizer outsmarts us on cases where breaking the comment
costs considerably less than breaking after the comment. This patch addresses
this by ensuring that a newline is inserted between a block comment and the next
token.

Reviewers: djasper

Reviewed By: djasper

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D37695

llvm-svn: 315893
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 4eaa26a..3df0166 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -65,6 +65,27 @@
 TEST_F(FormatTestJS, BlockComments) {
   verifyFormat("/* aaaaaaaaaaaaa */ aaaaaaaaaaaaaaaaaaaaaaaaaaa(\n"
                "    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa);");
+  // Breaks after a single line block comment.
+  EXPECT_EQ("aaaaa = bbbb.ccccccccccccccc(\n"
+            "    /** @type_{!cccc.rrrrrrr.MMMMMMMMMMMM.LLLLLLLLLLL.lala} */\n"
+            "    mediaMessage);",
+            format("aaaaa = bbbb.ccccccccccccccc(\n"
+                   "    /** "
+                   "@type_{!cccc.rrrrrrr.MMMMMMMMMMMM.LLLLLLLLLLL.lala} */ "
+                   "mediaMessage);",
+                   getGoogleJSStyleWithColumns(70)));
+  // Breaks after a multiline block comment.
+  EXPECT_EQ(
+      "aaaaa = bbbb.ccccccccccccccc(\n"
+      "    /**\n"
+      "     * @type_{!cccc.rrrrrrr.MMMMMMMMMMMM.LLLLLLLLLLL.lala}\n"
+      "     */\n"
+      "    mediaMessage);",
+      format("aaaaa = bbbb.ccccccccccccccc(\n"
+             "    /**\n"
+             "     * @type_{!cccc.rrrrrrr.MMMMMMMMMMMM.LLLLLLLLLLL.lala}\n"
+             "     */ mediaMessage);",
+             getGoogleJSStyleWithColumns(70)));
 }
 
 TEST_F(FormatTestJS, JSDocComments) {