[clang-format] Add IndentPPDirectives Leave option

clang/docs/ClangFormatStyleOptions.rst

@@ -4426,6 +4426,21 @@ the configuration (without a prefix: ``Auto``).
          #endif
        #endif
 
+  * ``PPDIS_Leave`` (in configuration: ``Leave``)
+    Leaves indentation of directives as-is.
+
+    .. note::
+
+     Ignores ``PPIndentWidth``.
+
+    .. code-block:: c++
+
+      #if FOO
+        #if BAR
+      #include <foo>
+        #endif
+      #endif
+
 
 
 .. _IndentRequiresClause:

clang/docs/ReleaseNotes.rst

@@ -472,6 +472,7 @@ clang-format
 - Add ``SpaceInEmptyBraces`` option and set it to ``Always`` for WebKit style.
 - Add ``NumericLiteralCase`` option for enforcing character case in numeric
   literals.
+- Add ``Leave`` suboption to ``IndentPPDirectives``.
 
 libclang
 --------

clang/include/clang/Format/Format.h

@@ -2976,7 +2976,19 @@ struct FormatStyle {
     ///      #endif
     ///    #endif
     /// \endcode
-    PPDIS_BeforeHash
+    PPDIS_BeforeHash,
+    /// Leaves indentation of directives as-is.
+    /// \note
+    ///  Ignores ``PPIndentWidth``.
+    /// \endnote
+    /// \code
+    ///   #if FOO
+    ///     #if BAR
+    ///   #include <foo>
+    ///     #endif
+    ///   #endif
+    /// \endcode
+    PPDIS_Leave
   };
 
   /// The preprocessor directive indenting style to use.

clang/lib/Format/ContinuationIndenter.cpp

@@ -780,19 +780,21 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
 
   // Indent preprocessor directives after the hash if required.
   int PPColumnCorrection = 0;
-  if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash &&
-      Previous.is(tok::hash) && State.FirstIndent > 0 &&
-      &Previous == State.Line->First &&
+  if (&Previous == State.Line->First && Previous.is(tok::hash) &&
       (State.Line->Type == LT_PreprocessorDirective ||
        State.Line->Type == LT_ImportStatement)) {
-    Spaces += State.FirstIndent;
-
-    // For preprocessor indent with tabs, State.Column will be 1 because of the
-    // hash. This causes second-level indents onward to have an extra space
-    // after the tabs. We avoid this misalignment by subtracting 1 from the
-    // column value passed to replaceWhitespace().
-    if (Style.UseTab != FormatStyle::UT_Never)
-      PPColumnCorrection = -1;
+    if (Style.IndentPPDirectives == FormatStyle::PPDIS_AfterHash) {
+      Spaces += State.FirstIndent;
+
+      // For preprocessor indent with tabs, State.Column will be 1 because of
+      // the hash. This causes second-level indents onward to have an extra
+      // space after the tabs. We avoid this misalignment by subtracting 1 from
+      // the column value passed to replaceWhitespace().
+      if (Style.UseTab != FormatStyle::UT_Never)
+        PPColumnCorrection = -1;
+    } else if (Style.IndentPPDirectives == FormatStyle::PPDIS_Leave) {
+      Spaces += Current.OriginalColumn - Previous.OriginalColumn - 1;
+    }
   }
 
   if (!DryRun) {

clang/lib/Format/Format.cpp

@@ -535,6 +535,7 @@ struct ScalarEnumerationTraits<FormatStyle::PPDirectiveIndentStyle> {
     IO.enumCase(Value, "None", FormatStyle::PPDIS_None);
     IO.enumCase(Value, "AfterHash", FormatStyle::PPDIS_AfterHash);
     IO.enumCase(Value, "BeforeHash", FormatStyle::PPDIS_BeforeHash);
+    IO.enumCase(Value, "Leave", FormatStyle::PPDIS_Leave);
   }
 };
 

clang/lib/Format/TokenAnnotator.cpp

@@ -3627,7 +3627,7 @@ void TokenAnnotator::setCommentLineLevels(
       // Align comments for preprocessor lines with the # in column 0 if
       // preprocessor lines are not indented. Otherwise, align with the next
       // line.
-      Line->Level = Style.IndentPPDirectives != FormatStyle::PPDIS_BeforeHash &&
+      Line->Level = Style.IndentPPDirectives < FormatStyle::PPDIS_BeforeHash &&
                             PPDirectiveOrImportStmt
                         ? 0
                         : NextNonCommentLine->Level;

clang/lib/Format/UnwrappedLineFormatter.cpp

@@ -62,10 +62,16 @@ class LevelIndentTracker {
     // having the right size in adjustToUnmodifiedline.
     if (Line.Level >= IndentForLevel.size())
       IndentForLevel.resize(Line.Level + 1, -1);
-    if (Style.IndentPPDirectives != FormatStyle::PPDIS_None &&
-        (Line.InPPDirective ||
-         (Style.IndentPPDirectives == FormatStyle::PPDIS_BeforeHash &&
-          Line.Type == LT_CommentAbovePPDirective))) {
+    if (Style.IndentPPDirectives == FormatStyle::PPDIS_Leave &&
+        (Line.InPPDirective || Line.Type == LT_CommentAbovePPDirective)) {
+      Indent = Line.InMacroBody
+                   ? (Line.Level - Line.PPLevel) * Style.IndentWidth +
+                         AdditionalIndent
+                   : Line.First->OriginalColumn;
+    } else if (Style.IndentPPDirectives != FormatStyle::PPDIS_None &&
+               (Line.InPPDirective ||
+                (Style.IndentPPDirectives == FormatStyle::PPDIS_BeforeHash &&
+                 Line.Type == LT_CommentAbovePPDirective))) {
       unsigned PPIndentWidth =
           (Style.PPIndentWidth >= 0) ? Style.PPIndentWidth : Style.IndentWidth;
       Indent = Line.InMacroBody
@@ -1656,7 +1662,7 @@ void UnwrappedLineFormatter::formatFirstToken(
   // Preprocessor directives get indented before the hash only if specified. In
   // Javascript import statements are indented like normal statements.
   if (!Style.isJavaScript() &&
-      Style.IndentPPDirectives != FormatStyle::PPDIS_BeforeHash &&
+      Style.IndentPPDirectives < FormatStyle::PPDIS_BeforeHash &&
       (Line.Type == LT_PreprocessorDirective ||
        Line.Type == LT_ImportStatement)) {
     Indent = 0;

clang/lib/Format/UnwrappedLineParser.cpp

@@ -162,15 +162,17 @@ UnwrappedLineParser::UnwrappedLineParser(
       LangOpts(getFormattingLangOpts(Style)), Keywords(Keywords),
       CommentPragmasRegex(Style.CommentPragmas), Tokens(nullptr),
       Callback(Callback), AllTokens(Tokens), PPBranchLevel(-1),
-      IncludeGuard(Style.IndentPPDirectives == FormatStyle::PPDIS_None
+      IncludeGuard(Style.IndentPPDirectives == FormatStyle::PPDIS_None ||
+                           Style.IndentPPDirectives == FormatStyle::PPDIS_Leave
                        ? IG_Rejected
                        : IG_Inited),
       IncludeGuardToken(nullptr), FirstStartColumn(FirstStartColumn),
       Macros(Style.Macros, SourceMgr, Style, Allocator, IdentTable) {}
 
 void UnwrappedLineParser::reset() {
   PPBranchLevel = -1;
-  IncludeGuard = Style.IndentPPDirectives == FormatStyle::PPDIS_None
+  IncludeGuard = Style.IndentPPDirectives == FormatStyle::PPDIS_None ||
+                         Style.IndentPPDirectives == FormatStyle::PPDIS_Leave
                      ? IG_Rejected
                      : IG_Inited;
   IncludeGuardToken = nullptr;
@@ -1140,7 +1142,8 @@ void UnwrappedLineParser::parsePPEndIf() {
   // If the #endif of a potential include guard is the last thing in the file,
   // then we found an include guard.
   if (IncludeGuard == IG_Defined && PPBranchLevel == -1 && Tokens->isEOF() &&
-      Style.IndentPPDirectives != FormatStyle::PPDIS_None) {
+      Style.IndentPPDirectives != FormatStyle::PPDIS_None &&
+      Style.IndentPPDirectives != FormatStyle::PPDIS_Leave) {
     IncludeGuard = IG_Found;
   }
 }

clang/unittests/Format/FormatTest.cpp

@@ -5564,6 +5564,63 @@ TEST_F(FormatTest, IndentsPPDirectiveWithPPIndentWidth) {
                " }",
                style);
 
+  style.IndentPPDirectives = FormatStyle::PPDIS_Leave;
+  style.IndentWidth = 4;
+  verifyNoChange("#ifndef foo\n"
+                 "#define foo\n"
+                 "if (emacs) {\n"
+                 "#ifdef is\n"
+                 "#define lit           \\\n"
+                 "    if (af) {         \\\n"
+                 "        return duh(); \\\n"
+                 "    }\n"
+                 "#endif\n"
+                 "}\n"
+                 "#endif",
+                 style);
+  verifyNoChange("#ifndef foo\n"
+                 "  #define foo\n"
+                 "if (emacs) {\n"
+                 "  #ifdef is\n"
+                 "#define lit           \\\n"
+                 "    if (af) {         \\\n"
+                 "        return duh(); \\\n"
+                 "    }\n"
+                 "  #endif\n"
+                 "}\n"
+                 "#endif",
+                 style);
+  verifyNoChange("  #ifndef foo\n"
+                 "#  define foo\n"
+                 "if (emacs) {\n"
+                 "#ifdef is\n"
+                 "  #  define lit       \\\n"
+                 "    if (af) {         \\\n"
+                 "        return duh(); \\\n"
+                 "    }\n"
+                 "#endif\n"
+                 "}\n"
+                 "  #endif",
+                 style);
+  verifyNoChange("#ifdef foo\n"
+                 "#else\n"
+                 "/* This is a comment */\n"
+                 "#ifdef BAR\n"
+                 "#endif\n"
+                 "#endif",
+                 style);
+
+  style.IndentWidth = 1;
+  style.PPIndentWidth = 4;
+  verifyNoChange("# if 1\n"
+                 "  #define X \\\n"
+                 " {          \\\n"
+                 "  x;        \\\n"
+                 "  x;        \\\n"
+                 " }\n"
+                 "# endif",
+                 style);
+
   style.IndentWidth = 4;
   style.PPIndentWidth = 1;
   style.IndentPPDirectives = FormatStyle::PPDIS_AfterHash;
@@ -25597,6 +25654,20 @@ TEST_F(FormatTest, SkipMacroDefinitionBody) {
                  "a",
                  Style);
 
+  Style.IndentPPDirectives = FormatStyle::PPDIS_Leave;
+  verifyNoChange("#if A\n"
+                 "#define A a\n"
+                 "#endif",
+                 Style);
+  verifyNoChange("#if A\n"
+                 "  #define A a\n"
+                 "#endif",
+                 Style);
+  verifyNoChange("#if A\n"
+                 "#  define A a\n"
+                 "#endif",
+                 Style);
+
   // Adjust indendations but don't change the definition.
   Style.IndentPPDirectives = FormatStyle::PPDIS_None;
   verifyNoChange("#if A\n"