[clang-format] do not break before @tags in JS comments

In JavaScript breaking before a `@tag` in a comment puts it on a new line, and
machinery that parses these comments will fail to understand such comments.

This adapts clang-format to not break before `@`. Similar functionality exists
for not breaking before `{`.

Reviewed By: mprobst

Differential Revision: https://reviews.llvm.org/D91078

1 files changed, 10 insertions, 11 deletions

diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 84d76c6..8963c9f 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -188,21 +188,10 @@ TEST_F(FormatTestJS, JSDocComments) {
 
   // Break a single line long jsdoc comment pragma.
   EXPECT_EQ("/**\n"
-            " * @returns {string} jsdoc line 12\n"
-            " */",
-            format("/** @returns {string} jsdoc line 12 */",
-                   getGoogleJSStyleWithColumns(20)));
-  EXPECT_EQ("/**\n"
             " * @returns {string}\n"
             " *     jsdoc line 12\n"
             " */",
             format("/** @returns {string} jsdoc line 12 */",
-                   getGoogleJSStyleWithColumns(25)));
-
-  EXPECT_EQ("/**\n"
-            " * @returns {string} jsdoc line 12\n"
-            " */",
-            format("/** @returns {string} jsdoc line 12  */",
                    getGoogleJSStyleWithColumns(20)));
 
   // FIXME: this overcounts the */ as a continuation of the 12 when breaking.
@@ -2194,6 +2183,16 @@ TEST_F(FormatTestJS, JSDocAnnotations) {
                  " */",
                  getGoogleJSStyleWithColumns(ColumnLimit));
   }
+  // don't break before @tags
+  verifyFormat("/**\n"
+               " * This\n"
+               " * tag @param\n"
+               " * stays.\n"
+               " */",
+               "/**\n"
+               " * This tag @param stays.\n"
+               " */",
+               getGoogleJSStyleWithColumns(13));
   verifyFormat("/**\n"
                " * @see http://very/very/long/url/is/long\n"
                " */",