[clang-format] Add LeftWithLastLine to AlignEscapedNewlines option (#93402)

Closes #92999.

1 files changed, 18 insertions, 11 deletions

diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index ed06d609..50531ae 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -1245,22 +1245,29 @@ void WhitespaceManager::alignTrailingComments(unsigned Start, unsigned End,
 }
 
 void WhitespaceManager::alignEscapedNewlines() {
-  if (Style.AlignEscapedNewlines == FormatStyle::ENAS_DontAlign)
+  const auto Align = Style.AlignEscapedNewlines;
+  if (Align == FormatStyle::ENAS_DontAlign)
     return;
 
-  bool AlignLeft = Style.AlignEscapedNewlines == FormatStyle::ENAS_Left;
-  unsigned MaxEndOfLine = AlignLeft ? 0 : Style.ColumnLimit;
+  const bool WithLastLine = Align == FormatStyle::ENAS_LeftWithLastLine;
+  const bool AlignLeft = Align == FormatStyle::ENAS_Left || WithLastLine;
+  const auto MaxColumn = Style.ColumnLimit;
+  unsigned MaxEndOfLine = AlignLeft ? 0 : MaxColumn;
   unsigned StartOfMacro = 0;
   for (unsigned i = 1, e = Changes.size(); i < e; ++i) {
     Change &C = Changes[i];
-    if (C.NewlinesBefore > 0) {
-      if (C.ContinuesPPDirective) {
-        MaxEndOfLine = std::max(C.PreviousEndOfTokenColumn + 2, MaxEndOfLine);
-      } else {
-        alignEscapedNewlines(StartOfMacro + 1, i, MaxEndOfLine);
-        MaxEndOfLine = AlignLeft ? 0 : Style.ColumnLimit;
-        StartOfMacro = i;
-      }
+    if (C.NewlinesBefore == 0 && (!WithLastLine || C.Tok->isNot(tok::eof)))
+      continue;
+    const bool InPPDirective = C.ContinuesPPDirective;
+    const auto BackslashColumn = C.PreviousEndOfTokenColumn + 2;
+    if (InPPDirective ||
+        (WithLastLine && (MaxColumn == 0 || BackslashColumn <= MaxColumn))) {
+      MaxEndOfLine = std::max(BackslashColumn, MaxEndOfLine);
+    }
+    if (!InPPDirective) {
+      alignEscapedNewlines(StartOfMacro + 1, i, MaxEndOfLine);
+      MaxEndOfLine = AlignLeft ? 0 : MaxColumn;
+      StartOfMacro = i;
     }
   }
   alignEscapedNewlines(StartOfMacro + 1, Changes.size(), MaxEndOfLine);