[clang-format] Fix comment levels between '} else {' and PPDirective.

Summary:
This fixes a regression exposed by r307795 and rL308725 in which the level of a
comment line between '} else {' and a preprocessor directive is incorrectly set
as the level of the '} else {' line. For example, this :
```
int f(int i) {
  if (i) {
    ++i;
  } else {
    // comment
#ifdef A
    --i;
#endif
  }
}
```
was formatted as:
```
int f(int i) {
  if (i) {
    ++i;
  } else {
  // comment
#ifdef A
    --i;
#endif
  }
}
```

Reviewers: djasper, klimek

Reviewed By: klimek

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D35794

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@308882 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Format/TokenAnnotator.cpp

@@ -2820,7 +2820,7 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
 }
 
 void TokenAnnotator::printDebugInfo(const AnnotatedLine &Line) {
-  llvm::errs() << "AnnotatedTokens:\n";
+  llvm::errs() << "AnnotatedTokens(L=" << Line.Level << "):\n";
   const FormatToken *Tok = Line.First;
   while (Tok) {
     llvm::errs() << " M=" << Tok->MustBreakBefore

lib/Format/UnwrappedLineParser.cpp

@@ -460,7 +460,7 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
   FormatTok->BlockKind = BK_Block;
 
   unsigned InitialLevel = Line->Level;
-  nextToken();
+  nextToken(/*LevelDifference=*/AddLevel ? 1 : 0);
 
   if (MacroBlock && FormatTok->is(tok::l_paren))
     parseParens();
@@ -486,9 +486,8 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
     return;
   }
 
-  flushComments(isOnNewLine(*FormatTok));
-  Line->Level = InitialLevel;
-  nextToken(); // Munch the closing brace.
+  // Munch the closing brace.
+  nextToken(/*LevelDifference=*/AddLevel ? -1 : 0);
 
   if (MacroBlock && FormatTok->is(tok::l_paren))
     parseParens();
@@ -496,6 +495,7 @@ void UnwrappedLineParser::parseBlock(bool MustBeDeclaration, bool AddLevel,
   if (MunchSemi && FormatTok->Tok.is(tok::semi))
     nextToken();
   Line->MatchingOpeningBlockLineIndex = OpeningLineIndex;
+  Line->Level = InitialLevel;
   if (OpeningLineIndex != UnwrappedLine::kInvalidIndex) {
     // Update the opening line to add the forward reference as well
     (*CurrentLines)[OpeningLineIndex].MatchingOpeningBlockLineIndex =
@@ -2288,13 +2288,13 @@ void UnwrappedLineParser::flushComments(bool NewlineBeforeNext) {
   CommentsBeforeNextToken.clear();
 }
 
-void UnwrappedLineParser::nextToken() {
+void UnwrappedLineParser::nextToken(int LevelDifference) {
   if (eof())
     return;
   flushComments(isOnNewLine(*FormatTok));
   pushToken(FormatTok);
   if (Style.Language != FormatStyle::LK_JavaScript)
-    readToken();
+    readToken(LevelDifference);
   else
     readTokenWithJavaScriptASI();
 }
@@ -2363,7 +2363,7 @@ void UnwrappedLineParser::distributeComments(
   }
 }
 
-void UnwrappedLineParser::readToken() {
+void UnwrappedLineParser::readToken(int LevelDifference) {
   SmallVector<FormatToken *, 1> Comments;
   do {
     FormatTok = Tokens->getNextToken();
@@ -2376,6 +2376,10 @@ void UnwrappedLineParser::readToken() {
       // directives only after that unwrapped line was finished later.
       bool SwitchToPreprocessorLines = !Line->Tokens.empty();
       ScopedLineState BlockState(*this, SwitchToPreprocessorLines);
+      assert((LevelDifference >= 0 ||
+              static_cast<unsigned>(-LevelDifference) <= Line->Level) &&
+             "LevelDifference makes Line->Level negative");
+      Line->Level += LevelDifference;
       // Comments stored before the preprocessor directive need to be output
       // before the preprocessor directive, at the same level as the
       // preprocessor directive, as we consider them to apply to the directive.

lib/Format/UnwrappedLineParser.h

@@ -123,9 +123,13 @@ private:
   void tryToParseJSFunction();
   void addUnwrappedLine();
   bool eof() const;
-  void nextToken();
+  // LevelDifference is the difference of levels after and before the current
+  // token. For example:
+  // - if the token is '{' and opens a block, LevelDifference is 1.
+  // - if the token is '}' and closes a block, LevelDifference is -1.
+  void nextToken(int LevelDifference = 0);
+  void readToken(int LevelDifference = 0);
   const FormatToken *getPreviousToken();
-  void readToken();
 
   // Decides which comment tokens should be added to the current line and which
   // should be added as comments before the next token.

unittests/Format/FormatTestComments.cpp

@@ -855,6 +855,48 @@ TEST_F(FormatTestComments, KeepsLevelOfCommentBeforePPDirective) {
                    "#endif\n"
                    "}"));
 
+  EXPECT_EQ("int f(int i) {\n"
+            "  if (true) {\n"
+            "    i++;\n"
+            "  } else {\n"
+            "    // comment in else\n"
+            "#ifdef A\n"
+            "    j++;\n"
+            "#endif\n"
+            "  }\n"
+            "}",
+            format("int f(int i) {\n"
+                   "  if (true) {\n"
+                   "    i++;\n"
+                   "  } else {\n"
+                   "  // comment in else\n"
+                   "#ifdef A\n"
+                   "    j++;\n"
+                   "#endif\n"
+                   "  }\n"
+                   "}"));
+
+  EXPECT_EQ("int f(int i) {\n"
+            "  if (true) {\n"
+            "    i++;\n"
+            "  } else {\n"
+            "    /* comment in else */\n"
+            "#ifdef A\n"
+            "    j++;\n"
+            "#endif\n"
+            "  }\n"
+            "}",
+            format("int f(int i) {\n"
+                   "  if (true) {\n"
+                   "    i++;\n"
+                   "  } else {\n"
+                   "  /* comment in else */\n"
+                   "#ifdef A\n"
+                   "    j++;\n"
+                   "#endif\n"
+                   "  }\n"
+                   "}"));
+
   // Keep the current level if there is an empty line between the comment and
   // the preprocessor directive.
   EXPECT_EQ("void f() {\n"
@@ -912,8 +954,55 @@ TEST_F(FormatTestComments, KeepsLevelOfCommentBeforePPDirective) {
                    "#endif\n"
                    "}"));
 
+  EXPECT_EQ("int f(int i) {\n"
+            "  if (true) {\n"
+            "    i++;\n"
+            "  } else {\n"
+            "    // comment in else\n"
+            "\n"
+            "#ifdef A\n"
+            "    j++;\n"
+            "#endif\n"
+            "  }\n"
+            "}",
+            format("int f(int i) {\n"
+                   "  if (true) {\n"
+                   "    i++;\n"
+                   "  } else {\n"
+                   "// comment in else\n"
+                   "\n"
+                   "#ifdef A\n"
+                   "    j++;\n"
+                   "#endif\n"
+                   "  }\n"
+                   "}"));
+
+  EXPECT_EQ("int f(int i) {\n"
+            "  if (true) {\n"
+            "    i++;\n"
+            "  } else {\n"
+            "    /* comment in else */\n"
+            "\n"
+            "#ifdef A\n"
+            "    j++;\n"
+            "#endif\n"
+            "  }\n"
+            "}",
+            format("int f(int i) {\n"
+                   "  if (true) {\n"
+                   "    i++;\n"
+                   "  } else {\n"
+                   "/* comment in else */\n"
+                   "\n"
+                   "#ifdef A\n"
+                   "    j++;\n"
+                   "#endif\n"
+                   "  }\n"
+                   "}"));
+
   // Align with the preprocessor directive if the comment was originally aligned
-  // with the preprocessor directive.
+  // with the preprocessor directive and there is no newline between the comment
+  // and the preprocessor directive.
   EXPECT_EQ("void f() {\n"
             "  int i;\n"
             "/* comment */\n"
@@ -945,6 +1034,48 @@ TEST_F(FormatTestComments, KeepsLevelOfCommentBeforePPDirective) {
                    "  int j;\n"
                    "#endif\n"
                    "}"));
+
+  EXPECT_EQ("int f(int i) {\n"
+            "  if (true) {\n"
+            "    i++;\n"
+            "  } else {\n"
+            "// comment in else\n"
+            "#ifdef A\n"
+            "    j++;\n"
+            "#endif\n"
+            "  }\n"
+            "}",
+            format("int f(int i) {\n"
+                   "  if (true) {\n"
+                   "    i++;\n"
+                   "  } else {\n"
+                   " // comment in else\n"
+                   " #ifdef A\n"
+                   "    j++;\n"
+                   "#endif\n"
+                   "  }\n"
+                   "}"));
+
+  EXPECT_EQ("int f(int i) {\n"
+            "  if (true) {\n"
+            "    i++;\n"
+            "  } else {\n"
+            "/* comment in else */\n"
+            "#ifdef A\n"
+            "    j++;\n"
+            "#endif\n"
+            "  }\n"
+            "}",
+            format("int f(int i) {\n"
+                   "  if (true) {\n"
+                   "    i++;\n"
+                   "  } else {\n"
+                   " /* comment in else */\n"
+                   " #ifdef A\n"
+                   "    j++;\n"
+                   "#endif\n"
+                   "  }\n"
+                   "}"));
 }
 
 TEST_F(FormatTestComments, SplitsLongLinesInComments) {