Index: clang/lib/Format/DefinitionBlockSeparator.cpp
===================================================================
--- clang/lib/Format/DefinitionBlockSeparator.cpp
+++ clang/lib/Format/DefinitionBlockSeparator.cpp
@@ -35,18 +35,31 @@
   const bool IsNeverStyle =
       Style.SeparateDefinitionBlocks == FormatStyle::SDS_Never;
   const AdditionalKeywords &ExtraKeywords = Tokens.getKeywords();
-  auto LikelyDefinition = [this, ExtraKeywords](const AnnotatedLine *Line,
-                                                bool ExcludeEnum = false) {
+  auto GetBracketLevelChange = [](const FormatToken *Tok) {
+    if (Tok->isOneOf(tok::l_brace, tok::l_paren, tok::l_square))
+      return 1;
+    else if (Tok->isOneOf(tok::r_brace, tok::r_paren, tok::r_square))
+      return -1;
+    else
+      return 0;
+  };
+  auto LikelyDefinition = [&](const AnnotatedLine *Line,
+                              bool ExcludeEnum = false) {
     if ((Line->MightBeFunctionDecl && Line->mightBeFunctionDefinition()) ||
         Line->startsWithNamespace())
       return true;
     FormatToken *CurrentToken = Line->First;
+    int BracketLevel = 0;
     while (CurrentToken) {
-      if (CurrentToken->isOneOf(tok::kw_class, tok::kw_struct) ||
-          (Style.isJavaScript() && CurrentToken->is(ExtraKeywords.kw_function)))
-        return true;
-      if (!ExcludeEnum && CurrentToken->is(tok::kw_enum))
-        return true;
+      if (BracketLevel == 0) {
+        if ((CurrentToken->isOneOf(tok::kw_class, tok::kw_struct) ||
+             (Style.isJavaScript() &&
+              CurrentToken->is(ExtraKeywords.kw_function))))
+          return true;
+        if (!ExcludeEnum && CurrentToken->is(tok::kw_enum))
+          return true;
+      }
+      BracketLevel += GetBracketLevelChange(CurrentToken);
       CurrentToken = CurrentToken->Next;
     }
     return false;
@@ -104,11 +117,15 @@
     const auto HasEnumOnLine = [&]() {
       FormatToken *CurrentToken = CurrentLine->First;
       bool FoundEnumKeyword = false;
+      int BracketLevel = 0;
       while (CurrentToken) {
-        if (CurrentToken->is(tok::kw_enum))
-          FoundEnumKeyword = true;
-        else if (FoundEnumKeyword && CurrentToken->is(tok::l_brace))
-          return true;
+        if (BracketLevel == 0) {
+          if (CurrentToken->is(tok::kw_enum))
+            FoundEnumKeyword = true;
+          else if (FoundEnumKeyword && CurrentToken->is(tok::l_brace))
+            return true;
+        }
+        BracketLevel += GetBracketLevelChange(CurrentToken);
         CurrentToken = CurrentToken->Next;
       }
       return FoundEnumKeyword && I + 1 < Lines.size() &&
Index: clang/unittests/Format/DefinitionBlockSeparatorTest.cpp
===================================================================
--- clang/unittests/Format/DefinitionBlockSeparatorTest.cpp
+++ clang/unittests/Format/DefinitionBlockSeparatorTest.cpp
@@ -302,6 +302,9 @@
                       "\n"
                       "int bar2(int j, int k) {\n"
                       "  int r = j / k;\n"
+                      "  if (struct S = getS()) {\n"
+                      "    // if condition\n"
+                      "  }\n"
                       "  return r;\n"
                       "}\n"
                       "\n"
@@ -355,6 +358,9 @@
                         "\n"
                         "int bar2(int j, int k) {\n"
                         "  int r = j / k;\n"
+                        "  if (struct S = getS()) {\n"
+                        "    // if condition\n"
+                        "  }\n"
                         "  return r;\n"
                         "}\n"
                         "\n"
@@ -412,6 +418,10 @@
                "int bar2(int j, int k)\n"
                "{\n"
                "  int r = j / k;\n"
+               "  if (struct S = getS())\n"
+               "  {\n"
+               "    // if condition\n"
+               "  }\n"
                "  return r;\n"
                "}\n"
                "\n"
@@ -465,6 +475,9 @@
                         "\n"
                         "int bar2(int j, int k) {\n"
                         "  int r = j / k;\n"
+                        "  if (struct S = getS()) {\n"
+                        "    // if condition\n"
+                        "  }\n"
                         "  return r;\n"
                         "}\n"
                         "\n"