2 files changed, 24 insertions, 6 deletions
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index dd14fcd..9bbb33c 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -876,27 +876,28 @@ template <> struct MappingTraits<FormatStyle::TrailingCommentsAlignmentStyle> {
                         FormatStyle::TrailingCommentsAlignmentStyle &Value) {
     IO.enumCase(Value, "Leave",
                 FormatStyle::TrailingCommentsAlignmentStyle(
-                    {FormatStyle::TCAS_Leave, 0}));
+                    {FormatStyle::TCAS_Leave, 0, true}));
 
     IO.enumCase(Value, "Always",
                 FormatStyle::TrailingCommentsAlignmentStyle(
-                    {FormatStyle::TCAS_Always, 0}));
+                    {FormatStyle::TCAS_Always, 0, true}));
 
     IO.enumCase(Value, "Never",
                 FormatStyle::TrailingCommentsAlignmentStyle(
-                    {FormatStyle::TCAS_Never, 0}));
+                    {FormatStyle::TCAS_Never, 0, true}));
 
     // For backwards compatibility
     IO.enumCase(Value, "true",
                 FormatStyle::TrailingCommentsAlignmentStyle(
-                    {FormatStyle::TCAS_Always, 0}));
+                    {FormatStyle::TCAS_Always, 0, true}));
     IO.enumCase(Value, "false",
                 FormatStyle::TrailingCommentsAlignmentStyle(
-                    {FormatStyle::TCAS_Never, 0}));
+                    {FormatStyle::TCAS_Never, 0, true}));
   }
 
   static void mapping(IO &IO,
                       FormatStyle::TrailingCommentsAlignmentStyle &Value) {
+    IO.mapOptional("AlignPPAndNotPP", Value.AlignPPAndNotPP);
     IO.mapOptional("Kind", Value.Kind);
     IO.mapOptional("OverEmptyLines", Value.OverEmptyLines);
   }
@@ -1651,6 +1652,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   LLVMStyle.AlignTrailingComments = {};
   LLVMStyle.AlignTrailingComments.Kind = FormatStyle::TCAS_Always;
   LLVMStyle.AlignTrailingComments.OverEmptyLines = 0;
+  LLVMStyle.AlignTrailingComments.AlignPPAndNotPP = true;
   LLVMStyle.AllowAllArgumentsOnNextLine = true;
   LLVMStyle.AllowAllParametersOfDeclarationOnNextLine = true;
   LLVMStyle.AllowBreakBeforeNoexceptSpecifier = FormatStyle::BBNSS_Never;
diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index 406c77c..fece384 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -1007,9 +1007,13 @@ void WhitespaceManager::alignTrailingComments() {
     return;
 
   const int Size = Changes.size();
+  if (Size == 0)
+    return;
+
   int MinColumn = 0;
   int StartOfSequence = 0;
   bool BreakBeforeNext = false;
+  bool IsInPP = Changes.front().Tok->Tok.is(tok::hash);
   int NewLineThreshold = 1;
   if (Style.AlignTrailingComments.Kind == FormatStyle::TCAS_Always)
     NewLineThreshold = Style.AlignTrailingComments.OverEmptyLines + 1;
@@ -1018,7 +1022,19 @@ void WhitespaceManager::alignTrailingComments() {
     auto &C = Changes[I];
     if (C.StartOfBlockComment)
       continue;
-    Newlines += C.NewlinesBefore;
+    if (C.NewlinesBefore != 0) {
+      Newlines += C.NewlinesBefore;
+      const bool WasInPP = std::exchange(
+          IsInPP, C.Tok->Tok.is(tok::hash) || (IsInPP && C.IsTrailingComment) ||
+                      C.ContinuesPPDirective);
+      if (IsInPP != WasInPP && !Style.AlignTrailingComments.AlignPPAndNotPP) {
+        alignTrailingComments(StartOfSequence, I, MinColumn);
+        MinColumn = 0;
+        MaxColumn = INT_MAX;
+        StartOfSequence = I;
+        Newlines = 0;
+      }
+    }
     if (!C.IsTrailingComment)
       continue;