clang-format: [JS] don't break comments before any '{'

[mprobst]

Summary

Previously, clang-format would avoid breaking before the first {
found, but then happily break before subsequent '{'s on the line. This
change fixes that by looking for the first location that has no opening
curly, if any.

This fixes the original commit by correcting the loop condition.

This reverts commit 66dc646e09b795b943668179c33d09da71a3b6bc.

lib/Format/BreakableToken.cpp

for (unsigned NumChars = 0;
     NumChars +=
         encoding::columnWidthWithTabs(Text.substr(MaxSplitBytes, BytesInChar),
                                       ContentStartColumn, TabWidth, Encoding);
     MaxSplitBytes += BytesInChar;
   }
 
   StringRef::size_type SpaceOffset = Text.find_last_of(Blanks, MaxSplitBytes);
 
+  static auto *const kNumberedListRegexp = new llvm::Regex("^[1-9][0-9]?\\.");
+  while (SpaceOffset != StringRef::npos) {
     // Do not split before a number followed by a dot: this would be interpreted
     // as a numbered list, which would prevent re-flowing in subsequent passes.
-  static auto *const kNumberedListRegexp = new llvm::Regex("^[1-9][0-9]?\\.");
-  if (SpaceOffset != StringRef::npos &&
-      kNumberedListRegexp->match(Text.substr(SpaceOffset).ltrim(Blanks)))
+    if (kNumberedListRegexp->match(Text.substr(SpaceOffset).ltrim(Blanks)))
       SpaceOffset = Text.find_last_of(Blanks, SpaceOffset);
     // In JavaScript, some @tags can be followed by {, and machinery that parses
     // these comments will fail to understand the comment if followed by a line
     // break. So avoid ever breaking before a {.
-  if (Style.Language == FormatStyle::LK_JavaScript &&
-      SpaceOffset != StringRef::npos && SpaceOffset + 1 < Text.size() &&
-      Text[SpaceOffset + 1] == '{')
+    else if (Style.Language == FormatStyle::LK_JavaScript &&
+             SpaceOffset + 1 < Text.size() && Text[SpaceOffset + 1] == '{')
       SpaceOffset = Text.find_last_of(Blanks, SpaceOffset);
+    else
+      break;
+  }
 
   if (SpaceOffset == StringRef::npos ||
       // Don't break at leading whitespace.
       Text.find_last_not_of(Blanks, SpaceOffset) == StringRef::npos) {
     // Make sure that we don't break at leading whitespace that
     // reaches past MaxSplit.
     StringRef::size_type FirstNonWhitespace = Text.find_first_not_of(Blanks);
     if (FirstNonWhitespace == StringRef::npos)

unittests/Format/FormatTestJS.cpp

TEST_F(FormatTestJS, JSDocAnnotations) {
   verifyFormat("/**\n"
                " * @param {canWrap\n"
                " *     onSpace}\n"
                " */",
                "/**\n"
                " * @param {canWrap onSpace}\n"
                " */",
                getGoogleJSStyleWithColumns(20));
+  // make sure clang-format doesn't break before *any* '{'
+  verifyFormat("/**\n"
+               " * @lala {lala {lalala\n"
+               " */\n",
+               "/**\n"
+               " * @lala {lala {lalala\n"
+               " */\n",
+               getGoogleJSStyleWithColumns(20));
   verifyFormat("/**\n"
                " * @see http://very/very/long/url/is/long\n"
                " */",
                "/**\n"
                " * @see http://very/very/long/url/is/long\n"
                " */",
                getGoogleJSStyleWithColumns(20));
   verifyFormat(