[clang-format] Re-land: Fixup #include guard indents after parseFile()

Summary:
When a preprocessor indent closes after the last line of normal code we do not
correctly fixup include guard indents. For example:

  #ifndef HEADER_H
  #define HEADER_H
  #if 1
  int i;
  #  define A 0
  #endif
  #endif

incorrectly reformats to:

  #ifndef HEADER_H
  #define HEADER_H
  #if 1
  int i;
  #    define A 0
  #  endif
  #endif

To resolve this issue we must fixup levels after parseFile(). Delaying
the fixup introduces a new state, so consolidate include guard search
state into an enum.

Reviewers: krasimir, klimek

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D42035

llvm-svn: 324246

clang/lib/Format/UnwrappedLineParser.cpp

@@ -234,14 +234,17 @@ UnwrappedLineParser::UnwrappedLineParser(const FormatStyle &Style,
       CurrentLines(&Lines), Style(Style), Keywords(Keywords),
       CommentPragmasRegex(Style.CommentPragmas), Tokens(nullptr),
       Callback(Callback), AllTokens(Tokens), PPBranchLevel(-1),
-      IfNdefCondition(nullptr), FoundIncludeGuardStart(false),
-      IncludeGuardRejected(false), FirstStartColumn(FirstStartColumn) {}
+      IncludeGuard(Style.IndentPPDirectives == FormatStyle::PPDIS_None
+                       ? IG_Rejected
+                       : IG_Inited),
+      IncludeGuardToken(nullptr), FirstStartColumn(FirstStartColumn) {}
 
 void UnwrappedLineParser::reset() {
   PPBranchLevel = -1;
-  IfNdefCondition = nullptr;
-  FoundIncludeGuardStart = false;
-  IncludeGuardRejected = false;
+  IncludeGuard = Style.IndentPPDirectives == FormatStyle::PPDIS_None
+                     ? IG_Rejected
+                     : IG_Inited;
+  IncludeGuardToken = nullptr;
   Line.reset(new UnwrappedLine);
   CommentsBeforeNextToken.clear();
   FormatTok = nullptr;
@@ -264,6 +267,14 @@ void UnwrappedLineParser::parse() {
 
     readToken();
     parseFile();
+
+    // If we found an include guard then all preprocessor directives (other than
+    // the guard) are over-indented by one.
+    if (IncludeGuard == IG_Found)
+      for (auto &Line : Lines)
+        if (Line.InPPDirective && Line.Level > 0)
+          --Line.Level;
+
     // Create line with eof token.
     pushToken(FormatTok);
     addUnwrappedLine();
@@ -724,26 +735,27 @@ void UnwrappedLineParser::parsePPIf(bool IfDef) {
   // If there's a #ifndef on the first line, and the only lines before it are
   // comments, it could be an include guard.
   bool MaybeIncludeGuard = IfNDef;
-  if (!IncludeGuardRejected && !FoundIncludeGuardStart && MaybeIncludeGuard) {
+  if (IncludeGuard == IG_Inited && MaybeIncludeGuard)
     for (auto &Line : Lines) {
       if (!Line.Tokens.front().Tok->is(tok::comment)) {
         MaybeIncludeGuard = false;
-        IncludeGuardRejected = true;
+        IncludeGuard = IG_Rejected;
         break;
       }
     }
-  }
   --PPBranchLevel;
   parsePPUnknown();
   ++PPBranchLevel;
-  if (!IncludeGuardRejected && !FoundIncludeGuardStart && MaybeIncludeGuard)
-    IfNdefCondition = IfCondition;
+  if (IncludeGuard == IG_Inited && MaybeIncludeGuard) {
+    IncludeGuard = IG_IfNdefed;
+    IncludeGuardToken = IfCondition;
+  }
 }
 
 void UnwrappedLineParser::parsePPElse() {
   // If a potential include guard has an #else, it's not an include guard.
-  if (FoundIncludeGuardStart && PPBranchLevel == 0)
-    FoundIncludeGuardStart = false;
+  if (IncludeGuard == IG_Defined && PPBranchLevel == 0)
+    IncludeGuard = IG_Rejected;
   conditionalCompilationAlternative();
   if (PPBranchLevel > -1)
     --PPBranchLevel;
@@ -757,34 +769,37 @@ void UnwrappedLineParser::parsePPEndIf() {
   conditionalCompilationEnd();
   parsePPUnknown();
   // If the #endif of a potential include guard is the last thing in the file,
-  // then we count it as a real include guard and subtract one from every
-  // preprocessor indent.
+  // then we found an include guard.
   unsigned TokenPosition = Tokens->getPosition();
   FormatToken *PeekNext = AllTokens[TokenPosition];
-  if (FoundIncludeGuardStart && PPBranchLevel == -1 && PeekNext->is(tok::eof) &&
+  if (IncludeGuard == IG_Defined && PPBranchLevel == -1 &&
+      PeekNext->is(tok::eof) &&
       Style.IndentPPDirectives != FormatStyle::PPDIS_None)
-    for (auto &Line : Lines)
-      if (Line.InPPDirective && Line.Level > 0)
-        --Line.Level;
+    IncludeGuard = IG_Found;
 }
 
 void UnwrappedLineParser::parsePPDefine() {
   nextToken();
 
   if (FormatTok->Tok.getKind() != tok::identifier) {
+    IncludeGuard = IG_Rejected;
+    IncludeGuardToken = nullptr;
     parsePPUnknown();
     return;
   }
-  if (IfNdefCondition && IfNdefCondition->TokenText == FormatTok->TokenText) {
-    FoundIncludeGuardStart = true;
+
+  if (IncludeGuard == IG_IfNdefed &&
+      IncludeGuardToken->TokenText == FormatTok->TokenText) {
+    IncludeGuard = IG_Defined;
+    IncludeGuardToken = nullptr;
     for (auto &Line : Lines) {
       if (!Line.Tokens.front().Tok->isOneOf(tok::comment, tok::hash)) {
-        FoundIncludeGuardStart = false;
+        IncludeGuard = IG_Rejected;
         break;
       }
     }
   }
-  IfNdefCondition = nullptr;
+
   nextToken();
   if (FormatTok->Tok.getKind() == tok::l_paren &&
       FormatTok->WhitespaceRange.getBegin() ==
@@ -811,7 +826,6 @@ void UnwrappedLineParser::parsePPUnknown() {
   if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash)
     Line->Level += PPBranchLevel + 1;
   addUnwrappedLine();
-  IfNdefCondition = nullptr;
 }
 
 // Here we blacklist certain tokens that are not usually the first token in an

clang/lib/Format/UnwrappedLineParser.h

@@ -248,10 +248,23 @@ private:
   // sequence.
   std::stack<int> PPChainBranchIndex;
 
-  // Contains the #ifndef condition for a potential include guard.
-  FormatToken *IfNdefCondition;
-  bool FoundIncludeGuardStart;
-  bool IncludeGuardRejected;
+  // Include guard search state. Used to fixup preprocessor indent levels
+  // so that include guards do not participate in indentation.
+  enum IncludeGuardState {
+    IG_Inited,   // Search started, looking for #ifndef.
+    IG_IfNdefed, // #ifndef found, IncludeGuardToken points to condition.
+    IG_Defined,  // Matching #define found, checking other requirements.
+    IG_Found,    // All requirements met, need to fix indents.
+    IG_Rejected, // Search failed or never started.
+  };
+
+  // Current state of include guard search.
+  IncludeGuardState IncludeGuard;
+
+  // Points to the #ifndef condition for a potential include guard. Null unless
+  // IncludeGuardState == IG_IfNdefed.
+  FormatToken *IncludeGuardToken;
+
   // Contains the first start column where the source begins. This is zero for
   // normal source code and may be nonzero when formatting a code fragment that
   // does not start at the beginning of the file.

clang/unittests/Format/FormatTest.cpp

@@ -2547,6 +2547,20 @@ TEST_F(FormatTest, IndentPreprocessorDirectives) {
                "#elif FOO\n"
                "#endif",
                Style);
+  // Non-identifier #define after potential include guard.
+  verifyFormat("#ifndef FOO\n"
+               "#  define 1\n"
+               "#endif\n",
+               Style);
+  // #if closes past last non-preprocessor line.
+  verifyFormat("#ifndef FOO\n"
+               "#define FOO\n"
+               "#if 1\n"
+               "int i;\n"
+               "#  define A 0\n"
+               "#endif\n"
+               "#endif\n",
+               Style);
   // FIXME: This doesn't handle the case where there's code between the
   // #ifndef and #define but all other conditions hold. This is because when
   // the #define line is parsed, UnwrappedLineParser::Lines doesn't hold the