[clang-format] Don't over-indent comment below unbraced body (#95354)

Fixes #45002.

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -112,6 +112,7 @@ class ScopedLineState {
     Parser.Line->PPLevel = PreBlockLine->PPLevel;
     Parser.Line->InPPDirective = PreBlockLine->InPPDirective;
     Parser.Line->InMacroBody = PreBlockLine->InMacroBody;
+    Parser.Line->UnbracedBodyLevel = PreBlockLine->UnbracedBodyLevel;
   }
 
   ~ScopedLineState() {
@@ -2708,7 +2709,9 @@ void UnwrappedLineParser::parseUnbracedBody(bool CheckEOF) {
 
   addUnwrappedLine();
   ++Line->Level;
+  ++Line->UnbracedBodyLevel;
   parseStructuralElement();
+  --Line->UnbracedBodyLevel;
 
   if (Tok) {
     assert(!Line->InPPDirective);
@@ -4836,6 +4839,8 @@ void UnwrappedLineParser::readToken(int LevelDifference) {
           PPBranchLevel > 0) {
         Line->Level += PPBranchLevel;
       }
+      assert(Line->Level >= Line->UnbracedBodyLevel);
+      Line->Level -= Line->UnbracedBodyLevel;
       flushComments(isOnNewLine(*FormatTok));
       parsePPDirective();
       PreviousWasComment = FormatTok->is(tok::comment);

clang/lib/Format/UnwrappedLineParser.h

@@ -49,6 +49,9 @@ struct UnwrappedLine {
   /// Whether it is part of a macro body.
   bool InMacroBody = false;
 
+  /// Nesting level of unbraced body of a control statement.
+  unsigned UnbracedBodyLevel = 0;
+
   bool MustBeDeclaration = false;
 
   /// Whether the parser has seen \c decltype(auto) in this line.

clang/unittests/Format/FormatTestComments.cpp

@@ -1087,6 +1087,36 @@ TEST_F(FormatTestComments, KeepsLevelOfCommentBeforePPDirective) {
                Style);
 }
 
+TEST_F(FormatTestComments, CommentsBetweenUnbracedBodyAndPPDirective) {
+  verifyFormat("{\n"
+               "  if (a)\n"
+               "    f(); // comment\n"
+               "#define A\n"
+               "}");
+
+  verifyFormat("{\n"
+               "  while (a)\n"
+               "    f();\n"
+               "// comment\n"
+               "#define A\n"
+               "}");
+
+  verifyNoChange("{\n"
+                 "  if (a)\n"
+                 "    f();\n"
+                 "  // comment\n"
+                 "#define A\n"
+                 "}");
+
+  verifyNoChange("{\n"
+                 "  while (a)\n"
+                 "    if (b)\n"
+                 "      f();\n"
+                 "  // comment\n"
+                 "#define A\n"
+                 "}");
+}
+
 TEST_F(FormatTestComments, SplitsLongLinesInComments) {
   // FIXME: Do we need to fix up the "  */" at the end?
   // It doesn't look like any of our current logic triggers this.