[clang-format++] Create a new variant of the clang-format tool to allow additional code mutating behaviour such as East/West Const Fixer

[MyDeveloperDay]

Summary

There has been much discussion about the relative merits of including East/West const fixer inclang-format over in D69764: [clang-format] Add Left/Right Const fixer capability on and off over the last 18 months

It seem we could not get to a concencus if this functionality should/shouldn't exist in clang-format mainly on the grounds that it broke the fundamental belief that clang-format should not modify the code (a precedent that had already been broken with SortIncludes)

As a compromise I'm suggesting a new tool which allows the introduction of such rules that can alter the code as well as format it. This allows those users who want to use this check to do so by switching to this binary.

[HazardyKnusperkeks]

This could be a way, but I will also state here that I prefer adding it to plain clang-format.

[MyDeveloperDay]

In D105943#2877886, @HazardyKnusperkeks wrote:

This could be a way, but I will also state here that I prefer adding it to plain clang-format.

I do too, and that is my preference, Perhaps this way we can establish this as a way of showing we can reliably mutate the code with confidence. For this and a few of the other ideas collectively our clang-format community has had.

If we are able to prove it has value then I would hope and fully expect in the future to be able to at least discuss revisiting that decision, but for now I feel we have to prove its worth.

clang/docs/ClangFormatStyleOptions.rst

**CompactNamespaces** (``bool``)
   wrapped:
 
   .. code-block:: c++
 
     namespace Foo { namespace Bar {
     namespace Extra {
     }}}
 
+**ConstPlacement** (``ConstPlacementStyle``)
+  Different ways to arrange const.
+
+  *This style is ONLY supported in clang-format++*
+
+  Possible values:
+
+  * ``CS_Leave`` (in configuration: ``Leave``)
+    Don't change const to either East/Right const or West/Left const.
+
+    .. code-block:: c++
+
+       int const a;
+       const int *a;
+
+  * ``CS_West`` (in configuration: ``West``)
+    Change type decorations to be West/Left const.
+
+    .. code-block:: c++
+
+       const int a;
+       const int *a;
+
+  * ``CS_East`` (in configuration: ``East``)
+    Change type decorations to be East/Right const.
+
+    .. code-block:: c++
+
+       int const a;
+       int const *a;
+
+
+
 **ConstructorInitializerAllOnOneLineOrOnePerLine** (``bool``)
   If the constructor initializers don't fit on a line, put each
   initializer on its own line.
 
   .. code-block:: c++
 
     true:
     SomeClass::Constructor()

clang/docs/ReleaseNotes.rst

 - Makes ``PointerAligment: Right`` working with ``AlignConsecutiveDeclarations``.
   (Fixes https://llvm.org/PR27353)
 
 - Option ``AlignArrayOfStructure`` has been added to allow for ordering array-like
   initializers.
 
 - Support for formatting JSON file (\*.json) has been added to clang-format.
 
+clang-format++
+--------------
+
+A new clang-format++ tool has been added, this is an experimental binary for clang-format functionality which enables capability which can mutate source code above and beyond the original goals of clang-format. The tool is there as a means of bringing these changes into clang-format without destabilizing the clang-format functionality.
+
+The goal of clang-format++ is to allow such changes which would normally not be considered 
+
+- Option ``ConstPlacement`` has been added in order to auto-arrange the positioning of `const`
+  in variable and parameter declarations to be either ``Right/East`` const or ``Left/West`` 
+  const .
+
 libclang
 --------
 
 - ...
 
 Static Analyzer
 ---------------
 

clang/include/clang/Format/Format.h

   /// which should not be split into lines or otherwise changed.
   /// \code
   ///    // CommentPragmas: '^ FOOBAR pragma:'
   ///    // Will leave the following line unaffected
   ///    #include <vector> // FOOBAR pragma: keep
   /// \endcode
   std::string CommentPragmas;
 
+  /// Different const alignment styles.
+  enum ConstPlacementStyle {
+    /// Don't change const to either East/Right const or West/Left const.
+    /// \code
+    ///    int const a;
+    ///    const int *a;
+    /// \endcode
+    CS_Leave,
+    /// Change type decorations to be West/Left const.
+    /// \code
+    ///    const int a;
+    ///    const int *a;
+    /// \endcode
+    CS_West,
+    /// Change type decorations to be East/Right const.
+    /// \code
+    ///    int const a;
+    ///    int const *a;
+    /// \endcode
+    CS_East
+  };
+
+  /// Different ways to arrange const.
+  ConstPlacementStyle ConstPlacement;
+
   /// Different ways to break inheritance list.
   enum BreakInheritanceListStyle : unsigned char {
     /// Break inheritance list before the colon and after the commas.
     /// \code
     ///    class Foo
     ///        : Base1,
     ///          Base2
     ///    {};
return AccessModifierOffset == R.AccessModifierOffset &&
            BreakBeforeBraces == R.BreakBeforeBraces &&
            BreakBeforeConceptDeclarations == R.BreakBeforeConceptDeclarations &&
            BreakBeforeTernaryOperators == R.BreakBeforeTernaryOperators &&
            BreakConstructorInitializers == R.BreakConstructorInitializers &&
            CompactNamespaces == R.CompactNamespaces &&
            BreakAfterJavaFieldAnnotations == R.BreakAfterJavaFieldAnnotations &&
            BreakStringLiterals == R.BreakStringLiterals &&
            ColumnLimit == R.ColumnLimit && CommentPragmas == R.CommentPragmas &&
+           ConstPlacement == R.ConstPlacement &&
            BreakInheritanceList == R.BreakInheritanceList &&
            ConstructorInitializerAllOnOneLineOrOnePerLine ==
                R.ConstructorInitializerAllOnOneLineOrOnePerLine &&
            ConstructorInitializerIndentWidth ==
                R.ConstructorInitializerIndentWidth &&
            ContinuationIndentWidth == R.ContinuationIndentWidth &&
            Cpp11BracedListStyle == R.Cpp11BracedListStyle &&
            DeriveLineEnding == R.DeriveLineEnding &&

 /// Returns the ``Replacements`` necessary to make all \p Ranges comply with
 /// \p Style.
 ///
 /// If ``Status`` is non-null, its value will be populated with the status of
 /// this formatting attempt. See \c FormattingAttemptStatus.
 tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
                                ArrayRef<tooling::Range> Ranges,
                                StringRef FileName = "<stdin>",
-                               FormattingAttemptStatus *Status = nullptr);
+                               FormattingAttemptStatus *Status = nullptr,
+                               bool MutatingPasses = false);
 
 /// Same as above, except if ``IncompleteFormat`` is non-null, its value
 /// will be set to true if any of the affected ranges were not formatted due to
 /// a non-recoverable syntax error.
 tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
                                ArrayRef<tooling::Range> Ranges,
                                StringRef FileName, bool *IncompleteFormat);
 

clang/lib/Format/CMakeLists.txt

add_clang_library(clangFormat
   MacroExpander.cpp
   NamespaceEndCommentsFixer.cpp
   SortJavaScriptImports.cpp
   TokenAnalyzer.cpp
   TokenAnnotator.cpp
   UnwrappedLineFormatter.cpp
   UnwrappedLineParser.cpp
   UsingDeclarationsSorter.cpp
+  EastWestConstFixer.cpp
   WhitespaceManager.cpp
 
   LINK_LIBS
   clangBasic
   clangLex
   clangToolingCore
   clangToolingInclusions
   )

clang/lib/Format/ContinuationIndenter.cpp

unsigned ContinuationIndenter::reformatRawStringLiteral(
   //   - if the raw string prefix does not start on a newline, it is the current
   //     indent.
   unsigned LastStartColumn =
       Current.NewlinesBefore ? FirstStartColumn - NewPrefixSize : CurrentIndent;
 
   std::pair<tooling::Replacements, unsigned> Fixes = internal::reformat(
       RawStringStyle, RawText, {tooling::Range(0, RawText.size())},
       FirstStartColumn, NextStartColumn, LastStartColumn, "<stdin>",
-      /*Status=*/nullptr);
+      /*Status=*/nullptr, /*MutatingPasses=*/false);
 
   auto NewCode = applyAllReplacements(RawText, Fixes.first);
   tooling::Replacements NoFixes;
   if (!NewCode) {
     return addMultilineToken(Current, State);
   }
   if (!DryRun) {
     if (NewDelimiter != OldDelimiter) {

clang/lib/Format/EastWestConstFixer.h

+//===--- EastWestConstFixer.h -----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file declares EastWestConstFixer, a TokenAnalyzer that
+/// enforces either east or west const depending on the style.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_FORMAT_EASTWESTCONSTFIXER_H
+#define LLVM_CLANG_LIB_FORMAT_EASTWESTCONSTFIXER_H
+
+#include "TokenAnalyzer.h"
+
+namespace clang {
+namespace format {
+
+class EastWestConstFixer : public TokenAnalyzer {
+public:
+  EastWestConstFixer(const Environment &Env, const FormatStyle &Style);
+
+  std::pair<tooling::Replacements, unsigned>
+  analyze(TokenAnnotator &Annotator,
+          SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
+          FormatTokenLexer &Tokens) override;
+};
+
+} // end namespace format
+} // end namespace clang
+
+#endif

clang/lib/Format/EastWestConstFixer.cpp

+//===--- EastWestConstFixer.cpp ---------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements EastWestConstFixer, a TokenAnalyzer that
+/// enforces either east or west const depending on the style.
+///
+//===----------------------------------------------------------------------===//
+
+#include "EastWestConstFixer.h"
+#include "FormatToken.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Regex.h"
+
+#include <algorithm>
+
+namespace clang {
+namespace format {
+
+static void replaceToken(const SourceManager &SourceMgr,
+                         tooling::Replacements &Fixes,
+                         const CharSourceRange &Range, std::string NewText) {
+  auto Replacement = tooling::Replacement(SourceMgr, Range, NewText);
+  auto Err = Fixes.add(Replacement);
+
+  if (Err) {
+    llvm::errs() << "Error while rearranging const : "
+                 << llvm::toString(std::move(Err)) << "\n";
+  }
+}
+
+static void removeToken(const SourceManager &SourceMgr,
+                        tooling::Replacements &Fixes,
+                        const FormatToken *First) {
+  auto Range = CharSourceRange::getCharRange(First->getStartOfNonWhitespace(),
+                                             First->Tok.getEndLoc());
+  replaceToken(SourceMgr, Fixes, Range, "");
+}
+
+static void insertConstAfter(const SourceManager &SourceMgr,
+                             tooling::Replacements &Fixes,
+                             const FormatToken *First) {
+  FormatToken *Next = First->Next;
+  if (!Next) {
+    return;
+  }
+  auto Range = CharSourceRange::getCharRange(
+      Next->getStartOfNonWhitespace(), Next->Next->getStartOfNonWhitespace());
+
+  std::string NewText = " const ";
+  NewText += Next->TokenText;
+
+  replaceToken(SourceMgr, Fixes, Range, NewText);
+}
+
+static void insertConstBefore(const SourceManager &SourceMgr,
+                              tooling::Replacements &Fixes,
+                              const FormatToken *First) {
+  auto Range = CharSourceRange::getCharRange(
+      First->getStartOfNonWhitespace(), First->Next->getStartOfNonWhitespace());
+
+  std::string NewText = " const ";
+  NewText += First->TokenText;
+
+  replaceToken(SourceMgr, Fixes, Range, NewText);
+}
+
+static void rotateTokens(const SourceManager &SourceMgr,
+                         tooling::Replacements &Fixes, const FormatToken *First,
+                         const FormatToken *Last, bool Left) {
+  auto *End = Last;
+  auto *Begin = First;
+  if (!Left) {
+    End = Last->Next;
+    Begin = First->Next;
+  }
+
+  std::string NewText;
+  // If we are rotating to the left we move the Last token to the front.
+  if (Left) {
+    NewText += Last->TokenText;
+    NewText += " ";
+  }
+
+  // Then move through the other tokens.
+  auto *Tok = Begin;
+  while (Tok != End) {
+    if (!NewText.empty())
+      NewText += " ";
+
+    NewText += Tok->TokenText;
+    Tok = Tok->Next;
+  }
+
+  // If we are rotating to the right we move the first token to the back.
+  if (!Left) {
+    NewText += " ";
+    NewText += First->TokenText;
+  }
+
+  auto Range = CharSourceRange::getCharRange(First->getStartOfNonWhitespace(),
+                                             Last->Tok.getEndLoc());
+
+  replaceToken(SourceMgr, Fixes, Range, NewText);
+}
+
+static bool isCVQualifierOrType(const FormatToken *Tok) {
+  return Tok && (Tok->isSimpleTypeSpecifier() ||
+                 Tok->isOneOf(tok::kw_volatile, tok::kw_auto));
+}
+
+// If a token is an identifier and it's upper case, it could
+// be a macro and hence we need to be able to ignore it.
+static bool isPossibleMacro(const FormatToken *Tok) {
+  if (!Tok)
+    return false;
+
+  if (!Tok->is(tok::identifier))
+    return false;
+
+  if (Tok->TokenText.upper() == Tok->TokenText.str())
+    return true;
+
+  return false;
+}
+
+static FormatToken *analyzeEast(const SourceManager &SourceMgr,
+                                const AdditionalKeywords &Keywords,
+                                tooling::Replacements &Fixes,
+                                FormatToken *Tok) {
+  // We only need to think about streams that begin with const.
+  if (!Tok->is(tok::kw_const)) {
+    return Tok;
+  }
+  // Don't concern yourself if nothing follows const.
+  if (!Tok->Next) {
+    return Tok;
+  }
+  if (isPossibleMacro(Tok->Next)) {
+    return Tok;
+  }
+  FormatToken *Const = Tok;
+
+  FormatToken *Qualifier = Tok->Next;
+  FormatToken *LastQualifier = Qualifier;
+  while (Qualifier && isCVQualifierOrType(Qualifier)) {
+    LastQualifier = Qualifier;
+    Qualifier = Qualifier->Next;
+  }
+  if (LastQualifier && Qualifier != LastQualifier) {
+    rotateTokens(SourceMgr, Fixes, Const, LastQualifier, /*Left=*/false);
+    Tok = LastQualifier;
+  } else if (Tok->startsSequence(tok::kw_const, tok::identifier,
+                                 TT_TemplateOpener)) {
+    // Read from the TemplateOpener to
+    // TemplateCloser as in const ArrayRef<int> a; const ArrayRef<int> &a;
+    FormatToken *EndTemplate = Tok->Next->Next->MatchingParen;
+    if (EndTemplate) {
+      // Move to the end of any template class members e.g.
+      // `Foo<int>::iterator`.
+      if (EndTemplate->startsSequence(TT_TemplateCloser, tok::coloncolon,
+                                      tok::identifier)) {
+        EndTemplate = EndTemplate->Next->Next;
+      }
+    }
+    if (EndTemplate && EndTemplate->Next &&
+        !EndTemplate->Next->isOneOf(tok::equal, tok::l_paren)) {
+      // Remove the const.
+      insertConstAfter(SourceMgr, Fixes, EndTemplate);
+      removeToken(SourceMgr, Fixes, Tok);
+      return Tok;
+    }
+  } else if (Tok->startsSequence(tok::kw_const, tok::identifier)) {
+    FormatToken *Next = Tok->Next;
+    // The case  `const Foo` -> `Foo const`
+    // The case  `const Foo *` -> `Foo const *`
+    // The case  `const Foo &` -> `Foo const &`
+    // The case  `const Foo &&` -> `Foo const &&`
+    // The case  `const std::Foo &&` -> `std::Foo const &&`
+    // The case  `const std::Foo<T> &&` -> `std::Foo<T> const &&`
+    while (Next && Next->isOneOf(tok::identifier, tok::coloncolon)) {
+      Next = Next->Next;
+    }
+    if (Next && Next->is(TT_TemplateOpener)) {
+      Next = Next->MatchingParen;
+      // Move to the end of any template class members e.g.
+      // `Foo<int>::iterator`.
+      if (Next && Next->startsSequence(TT_TemplateCloser, tok::coloncolon,
+                                       tok::identifier)) {
+        Next = Next->Next->Next;
+        return Tok;
+      }
+      Next = Next->Next;
+    }
+    if (Next && Next->isOneOf(tok::star, tok::amp, tok::ampamp) &&
+        !Tok->Next->isOneOf(Keywords.kw_override, Keywords.kw_final)) {
+      if (Next->Previous && !Next->Previous->is(tok::kw_const)) {
+        insertConstAfter(SourceMgr, Fixes, Next->Previous);
+        removeToken(SourceMgr, Fixes, Const);
+      }
+      return Next;
+    }
+  }
+
+  return Tok;
+}
+
+static FormatToken *analyzeWest(const SourceManager &SourceMgr,
+                                const AdditionalKeywords &Keywords,
+                                tooling::Replacements &Fixes,
+                                FormatToken *Tok) {
+  // if Tok is an identifier and possibly a macro then don't convert
+  if (isPossibleMacro(Tok)) {
+    return Tok;
+  }
+
+  FormatToken *Qualifier = Tok;
+  FormatToken *LastQualifier = Qualifier;
+  while (Qualifier && isCVQualifierOrType(Qualifier)) {
+    LastQualifier = Qualifier;
+    Qualifier = Qualifier->Next;
+    if (Qualifier && Qualifier->is(tok::kw_const)) {
+      break;
+    }
+  }
+  if (LastQualifier && Qualifier != LastQualifier &&
+      Qualifier->is(tok::kw_const)) {
+    rotateTokens(SourceMgr, Fixes, Tok, Qualifier, /*Left=*/true);
+    Tok = Qualifier->Next;
+  } else if (Tok->startsSequence(tok::identifier, tok::kw_const)) {
+    if (Tok->Next->Next && Tok->Next->Next->isOneOf(tok::identifier, tok::star,
+                                                    tok::amp, tok::ampamp)) {
+      // Don't swap `::iterator const` to `::const iterator`.
+      if (!Tok->Previous ||
+          (Tok->Previous && !Tok->Previous->is(tok::coloncolon))) {
+        rotateTokens(SourceMgr, Fixes, Tok, Tok->Next, /*Left=*/true);
+      }
+    }
+  }
+  if (Tok->is(TT_TemplateOpener) && Tok->Next &&
+      (Tok->Next->is(tok::identifier) || Tok->Next->isSimpleTypeSpecifier()) &&
+      Tok->Next->Next && Tok->Next->Next->is(tok::kw_const)) {
+    rotateTokens(SourceMgr, Fixes, Tok->Next, Tok->Next->Next, /*Left=*/true);
+  }
+  if (Tok->startsSequence(tok::identifier) && Tok->Next) {
+    if (Tok->Previous &&
+        Tok->Previous->isOneOf(tok::star, tok::ampamp, tok::amp)) {
+      return Tok;
+    }
+    FormatToken *Next = Tok->Next;
+    // The case  `std::Foo<T> const` -> `const std::Foo<T> &&`
+    while (Next && Next->isOneOf(tok::identifier, tok::coloncolon)) {
+      Next = Next->Next;
+    }
+    if (Next && Next->Previous &&
+        Next->Previous->startsSequence(tok::identifier, TT_TemplateOpener)) {
+      // Read from to the end of the TemplateOpener to
+      // TemplateCloser const ArrayRef<int> a; const ArrayRef<int> &a;
+      Next = Next->MatchingParen->Next;
+
+      // Move to the end of any template class members e.g.
+      // `Foo<int>::iterator`.
+      if (Next && Next->startsSequence(tok::coloncolon, tok::identifier)) {
+        Next = Next->Next->Next;
+      }
+      if (Next && Next->is(tok::kw_const)) {
+        // Remove the const.
+        removeToken(SourceMgr, Fixes, Next);
+        insertConstBefore(SourceMgr, Fixes, Tok);
+        return Next;
+      }
+    }
+    if (Next && Next->Next &&
+        Next->Next->isOneOf(tok::amp, tok::ampamp, tok::star)) {
+      if (Next->is(tok::kw_const)) {
+        // Remove the const.
+        removeToken(SourceMgr, Fixes, Next);
+        insertConstBefore(SourceMgr, Fixes, Tok);
+        return Next;
+      }
+    }
+  }
+  return Tok;
+}
+
+EastWestConstFixer::EastWestConstFixer(const Environment &Env,
+                                       const FormatStyle &Style)
+    : TokenAnalyzer(Env, Style) {}
+
+std::pair<tooling::Replacements, unsigned>
+EastWestConstFixer::analyze(TokenAnnotator &Annotator,
+                            SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,
+                            FormatTokenLexer &Tokens) {
+  tooling::Replacements Fixes;
+  const AdditionalKeywords &Keywords = Tokens.getKeywords();
+  const SourceManager &SourceMgr = Env.getSourceManager();
+  AffectedRangeMgr.computeAffectedLines(AnnotatedLines);
+
+  for (size_t I = 0, E = AnnotatedLines.size(); I != E; ++I) {
+    FormatToken *First = AnnotatedLines[I]->First;
+    const auto *Last = AnnotatedLines[I]->Last;
+
+    for (auto *Tok = First; Tok && Tok != Last && Tok->Next; Tok = Tok->Next) {
+      if (Tok->is(tok::comment)) {
+        continue;
+      }
+      if (Style.ConstPlacement == FormatStyle::CS_East) {
+        Tok = analyzeEast(SourceMgr, Keywords, Fixes, Tok);
+      } else if (Style.ConstPlacement == FormatStyle::CS_West) {
+        Tok = analyzeWest(SourceMgr, Keywords, Fixes, Tok);
+      }
+    }
+  }
+  return {Fixes, 0};
+}
+} // namespace format
+} // namespace clang

clang/lib/Format/Format.cpp

 /// split into separate files as we go.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "clang/Format/Format.h"
 #include "AffectedRangeManager.h"
 #include "BreakableToken.h"
 #include "ContinuationIndenter.h"
+#include "EastWestConstFixer.h"
 #include "FormatInternal.h"
 #include "FormatTokenLexer.h"
 #include "NamespaceEndCommentsFixer.h"
 #include "SortJavaScriptImports.h"
 #include "TokenAnalyzer.h"
 #include "TokenAnnotator.h"
 #include "UnwrappedLineFormatter.h"
 #include "UnwrappedLineParser.h"
static void enumeration(IO &IO, FormatStyle::ShortBlockStyle &Value) {
     IO.enumCase(Value, "Never", FormatStyle::SBS_Never);
     IO.enumCase(Value, "false", FormatStyle::SBS_Never);
     IO.enumCase(Value, "Always", FormatStyle::SBS_Always);
     IO.enumCase(Value, "true", FormatStyle::SBS_Always);
     IO.enumCase(Value, "Empty", FormatStyle::SBS_Empty);
   }
 };
 
+template <> struct ScalarEnumerationTraits<FormatStyle::ConstPlacementStyle> {
+  static void enumeration(IO &IO, FormatStyle::ConstPlacementStyle &Value) {
+    IO.enumCase(Value, "Leave", FormatStyle::CS_Leave);
+    IO.enumCase(Value, "West", FormatStyle::CS_West);
+    IO.enumCase(Value, "East", FormatStyle::CS_East);
+
+    IO.enumCase(Value, "Left", FormatStyle::CS_West);
+    IO.enumCase(Value, "Right", FormatStyle::CS_East);
+  }
+};
+
 template <> struct ScalarEnumerationTraits<FormatStyle::ShortFunctionStyle> {
   static void enumeration(IO &IO, FormatStyle::ShortFunctionStyle &Value) {
     IO.enumCase(Value, "None", FormatStyle::SFS_None);
     IO.enumCase(Value, "false", FormatStyle::SFS_None);
     IO.enumCase(Value, "All", FormatStyle::SFS_All);
     IO.enumCase(Value, "true", FormatStyle::SFS_All);
     IO.enumCase(Value, "Inline", FormatStyle::SFS_Inline);
     IO.enumCase(Value, "InlineOnly", FormatStyle::SFS_InlineOnly);
if (BreakConstructorInitializersBeforeComma &&
         Style.BreakConstructorInitializers == FormatStyle::BCIS_BeforeColon)
       Style.BreakConstructorInitializers = FormatStyle::BCIS_BeforeComma;
 
     IO.mapOptional("BreakAfterJavaFieldAnnotations",
                    Style.BreakAfterJavaFieldAnnotations);
     IO.mapOptional("BreakStringLiterals", Style.BreakStringLiterals);
     IO.mapOptional("ColumnLimit", Style.ColumnLimit);
     IO.mapOptional("CommentPragmas", Style.CommentPragmas);
+    IO.mapOptional("ConstPlacement", Style.ConstPlacement);
     IO.mapOptional("CompactNamespaces", Style.CompactNamespaces);
     IO.mapOptional("ConstructorInitializerAllOnOneLineOrOnePerLine",
                    Style.ConstructorInitializerAllOnOneLineOrOnePerLine);
     IO.mapOptional("ConstructorInitializerIndentWidth",
                    Style.ConstructorInitializerIndentWidth);
     IO.mapOptional("ContinuationIndentWidth", Style.ContinuationIndentWidth);
     IO.mapOptional("Cpp11BracedListStyle", Style.Cpp11BracedListStyle);
     IO.mapOptional("DeriveLineEnding", Style.DeriveLineEnding);
LLVMStyle.BraceWrapping = {/*AfterCaseLabel=*/false,
                              /*SplitEmptyNamespace=*/true};
   LLVMStyle.IndentExternBlock = FormatStyle::IEBS_AfterExternBlock;
   LLVMStyle.BreakAfterJavaFieldAnnotations = false;
   LLVMStyle.BreakConstructorInitializers = FormatStyle::BCIS_BeforeColon;
   LLVMStyle.BreakInheritanceList = FormatStyle::BILS_BeforeColon;
   LLVMStyle.BreakStringLiterals = true;
   LLVMStyle.ColumnLimit = 80;
   LLVMStyle.CommentPragmas = "^ IWYU pragma:";
+  LLVMStyle.ConstPlacement = FormatStyle::CS_Leave;
   LLVMStyle.CompactNamespaces = false;
   LLVMStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = false;
   LLVMStyle.ConstructorInitializerIndentWidth = 4;
   LLVMStyle.ContinuationIndentWidth = 4;
   LLVMStyle.Cpp11BracedListStyle = true;
   LLVMStyle.DeriveLineEnding = true;
   LLVMStyle.DerivePointerAlignment = false;
   LLVMStyle.EmptyLineAfterAccessModifier = FormatStyle::ELAAMS_Never;
if (Language == FormatStyle::LK_Java) {
     GoogleStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Empty;
     // TODO: still under discussion whether to switch to SLS_All.
     GoogleStyle.AllowShortLambdasOnASingleLine = FormatStyle::SLS_Empty;
     GoogleStyle.AlwaysBreakBeforeMultilineStrings = false;
     GoogleStyle.BreakBeforeTernaryOperators = false;
     // taze:, triple slash directives (`/// <...`), tslint:, and @see, which is
     // commonly followed by overlong URLs.
     GoogleStyle.CommentPragmas = "(taze:|^/[ \t]*<|tslint:|@see)";
+    GoogleStyle.ConstPlacement = FormatStyle::CS_Leave;
     // TODO: enable once decided, in particular re disabling bin packing.
     // https://google.github.io/styleguide/jsguide.html#features-arrays-trailing-comma
     // GoogleStyle.InsertTrailingCommas = FormatStyle::TCS_Wrapped;
     GoogleStyle.MaxEmptyLinesToKeep = 3;
     GoogleStyle.NamespaceIndentation = FormatStyle::NI_All;
     GoogleStyle.SpacesInContainerLiterals = false;
     GoogleStyle.JavaScriptQuotes = FormatStyle::JSQS_Single;
     GoogleStyle.JavaScriptWrapImports = false;
FormatStyle getChromiumStyle(FormatStyle::LanguageKind Language) {
   //   on that.
   // - Finally, "If include reordering is harmful, put things in different
   //   blocks to prevent it" has been a recommendation for a long time that
   //   people are used to. We'll need a dev education push to change this to
   //   "If include reordering is harmful, put things in a different block and
   //   _prepend that with a comment_ to prevent it" before changing behavior.
   ChromiumStyle.IncludeStyle.IncludeBlocks =
       tooling::IncludeStyle::IBS_Preserve;
+  ChromiumStyle.ConstPlacement = FormatStyle::CS_Leave;
 
   if (Language == FormatStyle::LK_Java) {
     ChromiumStyle.AllowShortIfStatementsOnASingleLine =
         FormatStyle::SIS_WithoutElse;
     ChromiumStyle.BreakAfterJavaFieldAnnotations = true;
     ChromiumStyle.ContinuationIndentWidth = 8;
     ChromiumStyle.IndentWidth = 4;
     // See styleguide for import groups:
FormatStyle getMozillaStyle() {
   MozillaStyle.Cpp11BracedListStyle = false;
   MozillaStyle.FixNamespaceComments = false;
   MozillaStyle.IndentCaseLabels = true;
   MozillaStyle.ObjCSpaceAfterProperty = true;
   MozillaStyle.ObjCSpaceBeforeProtocolList = false;
   MozillaStyle.PenaltyReturnTypeOnItsOwnLine = 200;
   MozillaStyle.PointerAlignment = FormatStyle::PAS_Left;
   MozillaStyle.SpaceAfterTemplateKeyword = false;
+  MozillaStyle.ConstPlacement = FormatStyle::CS_Leave;
   return MozillaStyle;
 }
 
 FormatStyle getWebKitStyle() {
   FormatStyle Style = getLLVMStyle();
   Style.AccessModifierOffset = -4;
   Style.AlignAfterOpenBracket = FormatStyle::BAS_DontAlign;
   Style.AlignOperands = FormatStyle::OAS_DontAlign;
   Style.AlignTrailingComments = false;
   Style.AllowShortBlocksOnASingleLine = FormatStyle::SBS_Empty;
   Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
   Style.BreakBeforeBraces = FormatStyle::BS_WebKit;
   Style.BreakConstructorInitializers = FormatStyle::BCIS_BeforeComma;
   Style.Cpp11BracedListStyle = false;
   Style.ColumnLimit = 0;
   Style.FixNamespaceComments = false;
   Style.IndentWidth = 4;
   Style.NamespaceIndentation = FormatStyle::NI_Inner;
   Style.ObjCBlockIndentWidth = 4;
   Style.ObjCSpaceAfterProperty = true;
   Style.PointerAlignment = FormatStyle::PAS_Left;
   Style.SpaceBeforeCpp11BracedList = true;
   Style.SpaceInEmptyBlock = true;
+  Style.ConstPlacement = FormatStyle::CS_Leave;
   return Style;
 }
 
 FormatStyle getGNUStyle() {
   FormatStyle Style = getLLVMStyle();
   Style.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_All;
   Style.AlwaysBreakAfterReturnType = FormatStyle::RTBS_AllDefinitions;
   Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
   Style.BreakBeforeBraces = FormatStyle::BS_GNU;
   Style.BreakBeforeTernaryOperators = true;
   Style.Cpp11BracedListStyle = false;
   Style.ColumnLimit = 79;
   Style.FixNamespaceComments = false;
   Style.SpaceBeforeParens = FormatStyle::SBPO_Always;
   Style.Standard = FormatStyle::LS_Cpp03;
+  Style.ConstPlacement = FormatStyle::CS_Leave;
   return Style;
 }
 
 FormatStyle getMicrosoftStyle(FormatStyle::LanguageKind Language) {
   FormatStyle Style = getLLVMStyle(Language);
   Style.ColumnLimit = 120;
   Style.TabWidth = 4;
   Style.IndentWidth = 4;
FormatStyle getMicrosoftStyle(FormatStyle::LanguageKind Language) {
   Style.PenaltyReturnTypeOnItsOwnLine = 1000;
   Style.AllowShortEnumsOnASingleLine = false;
   Style.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_None;
   Style.AllowShortCaseLabelsOnASingleLine = false;
   Style.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
   Style.AllowShortLoopsOnASingleLine = false;
   Style.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
   Style.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
+  Style.ConstPlacement = FormatStyle::CS_Leave;
   return Style;
 }
 
 FormatStyle getNoStyle() {
   FormatStyle NoStyle = getLLVMStyle();
   NoStyle.DisableFormat = true;
   NoStyle.SortIncludes = FormatStyle::SI_Never;
   NoStyle.SortUsingDeclarations = false;
+  NoStyle.ConstPlacement = FormatStyle::CS_Leave;
   return NoStyle;
 }
 
 bool getPredefinedStyle(StringRef Name, FormatStyle::LanguageKind Language,
                         FormatStyle *Style) {
   if (Name.equals_insensitive("llvm")) {
     *Style = getLLVMStyle(Language);
   } else if (Name.equals_insensitive("chromium")) {
cleanupAroundReplacements(StringRef Code, const tooling::Replacements &Replaces,
   return processReplacements(Cleanup, Code, NewReplaces, Style);
 }
 
 namespace internal {
 std::pair<tooling::Replacements, unsigned>
 reformat(const FormatStyle &Style, StringRef Code,
          ArrayRef<tooling::Range> Ranges, unsigned FirstStartColumn,
          unsigned NextStartColumn, unsigned LastStartColumn, StringRef FileName,
-         FormattingAttemptStatus *Status) {
+         FormattingAttemptStatus *Status, bool mutatingPasses) {
   FormatStyle Expanded = expandPresets(Style);
   if (Expanded.DisableFormat)
     return {tooling::Replacements(), 0};
   if (isLikelyXml(Code))
     return {tooling::Replacements(), 0};
   if (Expanded.Language == FormatStyle::LK_JavaScript && isMpegTS(Code))
     return {tooling::Replacements(), 0};
 
if (Style.FixNamespaceComments)
       });
 
     if (Style.SortUsingDeclarations)
       Passes.emplace_back([&](const Environment &Env) {
         return UsingDeclarationsSorter(Env, Expanded).process();
       });
   }
 
+  if (mutatingPasses) {
+    if (Style.isCpp() && Style.ConstPlacement != FormatStyle::CS_Leave)
+      Passes.emplace_back([&](const Environment &Env) {
+        return EastWestConstFixer(Env, Expanded).process();
+      });
+  }
+
   if (Style.Language == FormatStyle::LK_JavaScript &&
       Style.JavaScriptQuotes != FormatStyle::JSQS_Leave)
     Passes.emplace_back([&](const Environment &Env) {
       return JavaScriptRequoter(Env, Expanded).process();
     });
 
   Passes.emplace_back([&](const Environment &Env) {
     return Formatter(Env, Expanded, Status).process();
reformat(const FormatStyle &Style, StringRef Code,
 
   return {Fixes, Penalty};
 }
 } // namespace internal
 
 tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
                                ArrayRef<tooling::Range> Ranges,
                                StringRef FileName,
-                               FormattingAttemptStatus *Status) {
+                               FormattingAttemptStatus *Status,
+                               bool MutatingPasses) {
   return internal::reformat(Style, Code, Ranges,
                             /*FirstStartColumn=*/0,
                             /*NextStartColumn=*/0,
-                            /*LastStartColumn=*/0, FileName, Status)
+                            /*LastStartColumn=*/0, FileName, Status,
+                            MutatingPasses)
       .first;
 }
 
 tooling::Replacements cleanup(const FormatStyle &Style, StringRef Code,
                               ArrayRef<tooling::Range> Ranges,
                               StringRef FileName) {
   // cleanups only apply to C++ (they mostly concern ctor commas etc.)
   if (Style.Language != FormatStyle::LK_Cpp)

clang/lib/Format/FormatInternal.h

 ///     returns 0.
 ///
 /// If ``Status`` is non-null, its value will be populated with the status of
 /// this formatting attempt. See \c FormattingAttemptStatus.
 std::pair<tooling::Replacements, unsigned>
 reformat(const FormatStyle &Style, StringRef Code,
          ArrayRef<tooling::Range> Ranges, unsigned FirstStartColumn,
          unsigned NextStartColumn, unsigned LastStartColumn, StringRef FileName,
-         FormattingAttemptStatus *Status);
+         FormattingAttemptStatus *Status, bool MutatingPasses);
 
 } // namespace internal
 } // namespace format
 } // namespace clang
 
 #endif

clang/tools/CMakeLists.txt

 create_subdirectory_options(CLANG TOOL)
 
 add_clang_subdirectory(diagtool)
 add_clang_subdirectory(driver)
 add_clang_subdirectory(apinotes-test)
 add_clang_subdirectory(clang-diff)
 add_clang_subdirectory(clang-format)
+add_clang_subdirectory(clang-format++)
 add_clang_subdirectory(clang-format-vs)
 add_clang_subdirectory(clang-fuzzer)
 add_clang_subdirectory(clang-import-test)
 add_clang_subdirectory(clang-offload-bundler)
 add_clang_subdirectory(clang-offload-wrapper)
 add_clang_subdirectory(clang-scan-deps)
 add_clang_subdirectory(clang-repl)
 

clang/tools/clang-format++/CMakeLists.txt

+set(LLVM_LINK_COMPONENTS support)
+
+add_clang_tool(clang-format++
+    ClangFormatPlusPlus.cpp
+  )
+
+set(CLANG_FORMAT_PLUSPLUS_LIB_DEPS
+  clangBasic
+  clangFormat
+  clangRewrite
+  clangToolingCore
+  )
+
+clang_target_link_libraries(clang-format++
+  PRIVATE
+  ${CLANG_FORMAT_PLUSPLUS_LIB_DEPS}
+  )

clang/tools/clang-format++/ClangFormatPlusPlus.cpp

+//===-- clang-format/ClangFormatPlusPlus.cpp - Clang FormatPlusPlus tool
+//------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements a variant of the clang-format tool but one
+/// that can actually modify the code
+///
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/DiagnosticOptions.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/Version.h"
+#include "clang/Format/Format.h"
+#include "clang/Rewrite/Core/Rewriter.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/Process.h"
+
+using namespace llvm;
+using clang::tooling::Replacements;
+
+static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden);
+
+// Mark all our options with this category, everything else (except for -version
+// and -help) will be hidden.
+static cl::OptionCategory ClangFormatPlusPlusCategory("Clang-modify options");
+
+static cl::list<unsigned>
+    Offsets("offset",
+            cl::desc("Format a range starting at this byte offset.\n"
+                     "Multiple ranges can be formatted by specifying\n"
+                     "several -offset and -length pairs.\n"
+                     "Can only be used with one input file."),
+            cl::cat(ClangFormatPlusPlusCategory));
+static cl::list<unsigned>
+    Lengths("length",
+            cl::desc("Format a range of this length (in bytes).\n"
+                     "Multiple ranges can be formatted by specifying\n"
+                     "several -offset and -length pairs.\n"
+                     "When only a single -offset is specified without\n"
+                     "-length, clang-format will format up to the end\n"
+                     "of the file.\n"
+                     "Can only be used with one input file."),
+            cl::cat(ClangFormatPlusPlusCategory));
+static cl::list<std::string>
+    LineRanges("lines",
+               cl::desc("<start line>:<end line> - format a range of\n"
+                        "lines (both 1-based).\n"
+                        "Multiple ranges can be formatted by specifying\n"
+                        "several -lines arguments.\n"
+                        "Can't be used with -offset and -length.\n"
+                        "Can only be used with one input file."),
+               cl::cat(ClangFormatPlusPlusCategory));
+static cl::opt<std::string>
+    Style("style", cl::desc(clang::format::StyleOptionHelpDescription),
+          cl::init(clang::format::DefaultFormatStyle),
+          cl::cat(ClangFormatPlusPlusCategory));
+static cl::opt<std::string>
+    FallbackStyle("fallback-style",
+                  cl::desc("The name of the predefined style used as a\n"
+                           "fallback in case clang-format is invoked with\n"
+                           "-style=file, but can not find the .clang-format\n"
+                           "file to use.\n"
+                           "Use -fallback-style=none to skip formatting."),
+                  cl::init(clang::format::DefaultFallbackStyle),
+                  cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<std::string> AssumeFileName(
+    "assume-filename",
+    cl::desc("Override filename used to determine the language.\n"
+             "When reading from stdin, clang-format assumes this\n"
+             "filename to determine the language."),
+    cl::init("<stdin>"), cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<bool> Inplace("i",
+                             cl::desc("Inplace edit <file>s, if specified."),
+                             cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<bool> OutputXML("output-replacements-xml",
+                               cl::desc("Output replacements as XML."),
+                               cl::cat(ClangFormatPlusPlusCategory));
+static cl::opt<bool>
+    DumpConfig("dump-config",
+               cl::desc("Dump configuration options to stdout and exit.\n"
+                        "Can be used with -style option."),
+               cl::cat(ClangFormatPlusPlusCategory));
+static cl::opt<unsigned>
+    Cursor("cursor",
+           cl::desc("The position of the cursor when invoking\n"
+                    "clang-format from an editor integration"),
+           cl::init(0), cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<bool> SortIncludes(
+    "sort-includes",
+    cl::desc("If set, overrides the include sorting behavior determined by the "
+             "SortIncludes style flag"),
+    cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<std::string> ConstPlacement(
+    "const-placement",
+    cl::desc("If set, overrides the const style behavior determined by the "
+             "ConstPlacement style flag"),
+    cl::init(""), cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<bool>
+    Verbose("verbose", cl::desc("If set, shows the list of processed files"),
+            cl::cat(ClangFormatPlusPlusCategory));
+
+// Use --dry-run to match other LLVM tools when you mean do it but don't
+// actually do it
+static cl::opt<bool>
+    DryRun("dry-run",
+           cl::desc("If set, do not actually make the formatting changes"),
+           cl::cat(ClangFormatPlusPlusCategory));
+
+// Use -n as a common command as an alias for --dry-run. (git and make use -n)
+static cl::alias DryRunShort("n", cl::desc("Alias for --dry-run"),
+                             cl::cat(ClangFormatPlusPlusCategory),
+                             cl::aliasopt(DryRun), cl::NotHidden);
+
+// Emulate being able to turn on/off the warning.
+static cl::opt<bool>
+    WarnFormat("Wclang-format-violations",
+               cl::desc("Warnings about individual formatting changes needed. "
+                        "Used only with --dry-run or -n"),
+               cl::init(true), cl::cat(ClangFormatPlusPlusCategory),
+               cl::Hidden);
+
+static cl::opt<bool>
+    NoWarnFormat("Wno-clang-format-violations",
+                 cl::desc("Do not warn about individual formatting changes "
+                          "needed. Used only with --dry-run or -n"),
+                 cl::init(false), cl::cat(ClangFormatPlusPlusCategory),
+                 cl::Hidden);
+
+static cl::opt<unsigned> ErrorLimit(
+    "ferror-limit",
+    cl::desc("Set the maximum number of clang-format errors to emit before "
+             "stopping (0 = no limit). Used only with --dry-run or -n"),
+    cl::init(0), cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<bool>
+    WarningsAsErrors("Werror",
+                     cl::desc("If set, changes formatting warnings to errors"),
+                     cl::cat(ClangFormatPlusPlusCategory));
+
+namespace {
+enum class WNoError { Unknown };
+}
+
+static cl::bits<WNoError> WNoErrorList(
+    "Wno-error",
+    cl::desc("If set don't error out on the specified warning type."),
+    cl::values(
+        clEnumValN(WNoError::Unknown, "unknown",
+                   "If set, unknown format options are only warned about.\n"
+                   "This can be used to enable formatting, even if the\n"
+                   "configuration contains unknown (newer) options.\n"
+                   "Use with caution, as this might lead to dramatically\n"
+                   "differing format depending on an option being\n"
+                   "supported or not.")),
+    cl::cat(ClangFormatPlusPlusCategory));
+
+static cl::opt<bool>
+    ShowColors("fcolor-diagnostics",
+               cl::desc("If set, and on a color-capable terminal controls "
+                        "whether or not to print diagnostics in color"),
+               cl::init(true), cl::cat(ClangFormatPlusPlusCategory),
+               cl::Hidden);
+
+static cl::opt<bool>
+    NoShowColors("fno-color-diagnostics",
+                 cl::desc("If set, and on a color-capable terminal controls "
+                          "whether or not to print diagnostics in color"),
+                 cl::init(false), cl::cat(ClangFormatPlusPlusCategory),
+                 cl::Hidden);
+
+static cl::list<std::string> FileNames(cl::Positional, cl::desc("[<file> ...]"),
+                                       cl::cat(ClangFormatPlusPlusCategory));
+
+namespace clang {
+namespace format {
+
+static FileID createInMemoryFile(StringRef FileName, MemoryBufferRef Source,
+                                 SourceManager &Sources, FileManager &Files,
+                                 llvm::vfs::InMemoryFileSystem *MemFS) {
+  MemFS->addFileNoOwn(FileName, 0, Source);
+  auto File = Files.getOptionalFileRef(FileName);
+  assert(File && "File not added to MemFS?");
+  return Sources.createFileID(*File, SourceLocation(), SrcMgr::C_User);
+}
+
+// Parses <start line>:<end line> input to a pair of line numbers.
+// Returns true on error.
+static bool parseLineRange(StringRef Input, unsigned &FromLine,
+                           unsigned &ToLine) {
+  std::pair<StringRef, StringRef> LineRange = Input.split(':');
+  return LineRange.first.getAsInteger(0, FromLine) ||
+         LineRange.second.getAsInteger(0, ToLine);
+}
+
+static bool fillRanges(MemoryBuffer *Code,
+                       std::vector<tooling::Range> &Ranges) {
+  IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> InMemoryFileSystem(
+      new llvm::vfs::InMemoryFileSystem);
+  FileManager Files(FileSystemOptions(), InMemoryFileSystem);
+  DiagnosticsEngine Diagnostics(
+      IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs),
+      new DiagnosticOptions);
+  SourceManager Sources(Diagnostics, Files);
+  FileID ID = createInMemoryFile("<irrelevant>", *Code, Sources, Files,
+                                 InMemoryFileSystem.get());
+  if (!LineRanges.empty()) {
+    if (!Offsets.empty() || !Lengths.empty()) {
+      errs() << "error: cannot use -lines with -offset/-length\n";
+      return true;
+    }
+
+    for (unsigned i = 0, e = LineRanges.size(); i < e; ++i) {
+      unsigned FromLine, ToLine;
+      if (parseLineRange(LineRanges[i], FromLine, ToLine)) {
+        errs() << "error: invalid <start line>:<end line> pair\n";
+        return true;
+      }
+      if (FromLine > ToLine) {
+        errs() << "error: start line should be less than end line\n";
+        return true;
+      }
+      SourceLocation Start = Sources.translateLineCol(ID, FromLine, 1);
+      SourceLocation End = Sources.translateLineCol(ID, ToLine, UINT_MAX);
+      if (Start.isInvalid() || End.isInvalid())
+        return true;
+      unsigned Offset = Sources.getFileOffset(Start);
+      unsigned Length = Sources.getFileOffset(End) - Offset;
+      Ranges.push_back(tooling::Range(Offset, Length));
+    }
+    return false;
+  }
+
+  if (Offsets.empty())
+    Offsets.push_back(0);
+  if (Offsets.size() != Lengths.size() &&
+      !(Offsets.size() == 1 && Lengths.empty())) {
+    errs() << "error: number of -offset and -length arguments must match.\n";
+    return true;
+  }
+  for (unsigned i = 0, e = Offsets.size(); i != e; ++i) {
+    if (Offsets[i] >= Code->getBufferSize()) {
+      errs() << "error: offset " << Offsets[i] << " is outside the file\n";
+      return true;
+    }
+    SourceLocation Start =
+        Sources.getLocForStartOfFile(ID).getLocWithOffset(Offsets[i]);
+    SourceLocation End;
+    if (i < Lengths.size()) {
+      if (Offsets[i] + Lengths[i] > Code->getBufferSize()) {
+        errs() << "error: invalid length " << Lengths[i]
+               << ", offset + length (" << Offsets[i] + Lengths[i]
+               << ") is outside the file.\n";
+        return true;
+      }
+      End = Start.getLocWithOffset(Lengths[i]);
+    } else {
+      End = Sources.getLocForEndOfFile(ID);
+    }
+    unsigned Offset = Sources.getFileOffset(Start);
+    unsigned Length = Sources.getFileOffset(End) - Offset;
+    Ranges.push_back(tooling::Range(Offset, Length));
+  }
+  return false;
+}
+
+static void outputReplacementXML(StringRef Text) {
+  // FIXME: When we sort includes, we need to make sure the stream is correct
+  // utf-8.
+  size_t From = 0;
+  size_t Index;
+  while ((Index = Text.find_first_of("\n\r<&", From)) != StringRef::npos) {
+    outs() << Text.substr(From, Index - From);
+    switch (Text[Index]) {
+    case '\n':
+      outs() << "&#10;";
+      break;
+    case '\r':
+      outs() << "&#13;";
+      break;
+    case '<':
+      outs() << "&lt;";
+      break;
+    case '&':
+      outs() << "&amp;";
+      break;
+    default:
+      llvm_unreachable("Unexpected character encountered!");
+    }
+    From = Index + 1;
+  }
+  outs() << Text.substr(From);
+}
+
+static void outputReplacementsXML(const Replacements &Replaces) {
+  for (const auto &R : Replaces) {
+    outs() << "<replacement "
+           << "offset='" << R.getOffset() << "' "
+           << "length='" << R.getLength() << "'>";
+    outputReplacementXML(R.getReplacementText());
+    outs() << "</replacement>\n";
+  }
+}
+
+static bool
+emitReplacementWarnings(const Replacements &Replaces, StringRef AssumedFileName,
+                        const std::unique_ptr<llvm::MemoryBuffer> &Code) {
+  if (Replaces.empty())
+    return false;
+
+  unsigned Errors = 0;
+  if (WarnFormat && !NoWarnFormat) {
+    llvm::SourceMgr Mgr;
+    const char *StartBuf = Code->getBufferStart();
+
+    Mgr.AddNewSourceBuffer(
+        MemoryBuffer::getMemBuffer(StartBuf, AssumedFileName), SMLoc());
+    for (const auto &R : Replaces) {
+      SMDiagnostic Diag = Mgr.GetMessage(
+          SMLoc::getFromPointer(StartBuf + R.getOffset()),
+          WarningsAsErrors ? SourceMgr::DiagKind::DK_Error
+                           : SourceMgr::DiagKind::DK_Warning,
+          "code should be clang-formatted [-Wclang-format-violations]");
+
+      Diag.print(nullptr, llvm::errs(), (ShowColors && !NoShowColors));
+      if (ErrorLimit && ++Errors >= ErrorLimit)
+        break;
+    }
+  }
+  return WarningsAsErrors;
+}
+
+static void outputXML(const Replacements &Replaces,
+                      const Replacements &FormatChanges,
+                      const FormattingAttemptStatus &Status,
+                      const cl::opt<unsigned> &Cursor,
+                      unsigned CursorPosition) {
+  outs() << "<?xml version='1.0'?>\n<replacements "
+            "xml:space='preserve' incomplete_format='"
+         << (Status.FormatComplete ? "false" : "true") << "'";
+  if (!Status.FormatComplete)
+    outs() << " line='" << Status.Line << "'";
+  outs() << ">\n";
+  if (Cursor.getNumOccurrences() != 0)
+    outs() << "<cursor>" << FormatChanges.getShiftedCodePosition(CursorPosition)
+           << "</cursor>\n";
+
+  outputReplacementsXML(Replaces);
+  outs() << "</replacements>\n";
+}
+
+// Returns true on error.
+static bool format(StringRef FileName) {
+  if (!OutputXML && Inplace && FileName == "-") {
+    errs() << "error: cannot use -i when reading from stdin.\n";
+    return false;
+  }
+  // On Windows, overwriting a file with an open file mapping doesn't work,
+  // so read the whole file into memory when formatting in-place.
+  ErrorOr<std::unique_ptr<MemoryBuffer>> CodeOrErr =
+      !OutputXML && Inplace ? MemoryBuffer::getFileAsStream(FileName)
+                            : MemoryBuffer::getFileOrSTDIN(FileName);
+  if (std::error_code EC = CodeOrErr.getError()) {
+    errs() << EC.message() << "\n";
+    return true;
+  }
+  std::unique_ptr<llvm::MemoryBuffer> Code = std::move(CodeOrErr.get());
+  if (Code->getBufferSize() == 0)
+    return false; // Empty files are formatted correctly.
+
+  StringRef BufStr = Code->getBuffer();
+
+  const char *InvalidBOM = SrcMgr::ContentCache::getInvalidBOM(BufStr);
+
+  if (InvalidBOM) {
+    errs() << "error: encoding with unsupported byte order mark \""
+           << InvalidBOM << "\" detected";
+    if (FileName != "-")
+      errs() << " in file '" << FileName << "'";
+    errs() << ".\n";
+    return true;
+  }
+
+  std::vector<tooling::Range> Ranges;
+  if (fillRanges(Code.get(), Ranges))
+    return true;
+  StringRef AssumedFileName = (FileName == "-") ? AssumeFileName : FileName;
+  if (AssumedFileName.empty()) {
+    llvm::errs() << "error: empty filenames are not allowed\n";
+    return true;
+  }
+
+  llvm::Expected<FormatStyle> FormatStyle =
+      getStyle(Style, AssumedFileName, FallbackStyle, Code->getBuffer(),
+               nullptr, WNoErrorList.isSet(WNoError::Unknown));
+  if (!FormatStyle) {
+    llvm::errs() << llvm::toString(FormatStyle.takeError()) << "\n";
+    return true;
+  }
+
+  StringRef ConstAlignment = ConstPlacement;
+
+  FormatStyle->ConstPlacement =
+      StringSwitch<FormatStyle::ConstPlacementStyle>(ConstAlignment.lower())
+          .Cases("right", "east", FormatStyle::CS_East)
+          .Cases("left", "west", FormatStyle::CS_West)
+          .Default(FormatStyle->ConstPlacement);
+
+  if (SortIncludes.getNumOccurrences() != 0) {
+    if (SortIncludes)
+      FormatStyle->SortIncludes = FormatStyle::SI_CaseSensitive;
+    else
+      FormatStyle->SortIncludes = FormatStyle::SI_Never;
+  }
+  unsigned CursorPosition = Cursor;
+  Replacements Replaces = sortIncludes(*FormatStyle, Code->getBuffer(), Ranges,
+                                       AssumedFileName, &CursorPosition);
+
+  // To format JSON insert a variable to trick the code into thinking its
+  // JavaScript.
+  if (FormatStyle->isJson()) {
+    auto Err = Replaces.add(tooling::Replacement(
+        tooling::Replacement(AssumedFileName, 0, 0, "x = ")));
+    if (Err) {
+      llvm::errs() << "Bad Json variable insertion\n";
+    }
+  }
+
+  auto ChangedCode = tooling::applyAllReplacements(Code->getBuffer(), Replaces);
+  if (!ChangedCode) {
+    llvm::errs() << llvm::toString(ChangedCode.takeError()) << "\n";
+    return true;
+  }
+  // Get new affected ranges after sorting `#includes`.
+  Ranges = tooling::calculateRangesAfterReplacements(Replaces, Ranges);
+  FormattingAttemptStatus Status;
+  Replacements FormatChanges =
+      reformat(*FormatStyle, *ChangedCode, Ranges, AssumedFileName, &Status);
+  Replaces = Replaces.merge(FormatChanges);
+  if (OutputXML || DryRun) {
+    if (DryRun) {
+      return emitReplacementWarnings(Replaces, AssumedFileName, Code);
+    } else {
+      outputXML(Replaces, FormatChanges, Status, Cursor, CursorPosition);
+    }
+  } else {
+    IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> InMemoryFileSystem(
+        new llvm::vfs::InMemoryFileSystem);
+    FileManager Files(FileSystemOptions(), InMemoryFileSystem);
+    DiagnosticsEngine Diagnostics(
+        IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs),
+        new DiagnosticOptions);
+    SourceManager Sources(Diagnostics, Files);
+    FileID ID = createInMemoryFile(AssumedFileName, *Code, Sources, Files,
+                                   InMemoryFileSystem.get());
+    Rewriter Rewrite(Sources, LangOptions());
+    tooling::applyAllReplacements(Replaces, Rewrite);
+    if (Inplace) {
+      if (Rewrite.overwriteChangedFiles())
+        return true;
+    } else {
+      if (Cursor.getNumOccurrences() != 0) {
+        outs() << "{ \"Cursor\": "
+               << FormatChanges.getShiftedCodePosition(CursorPosition)
+               << ", \"IncompleteFormat\": "
+               << (Status.FormatComplete ? "false" : "true");
+        if (!Status.FormatComplete)
+          outs() << ", \"Line\": " << Status.Line;
+        outs() << " }\n";
+      }
+      Rewrite.getEditBuffer(ID).write(outs());
+    }
+  }
+  return false;
+}
+
+} // namespace format
+} // namespace clang
+
+static void PrintVersion(raw_ostream &OS) {
+  OS << clang::getClangToolFullVersion("clang-format") << '\n';
+}
+
+// Dump the configuration.
+static int dumpConfig() {
+  StringRef FileName;
+  std::unique_ptr<llvm::MemoryBuffer> Code;
+  if (FileNames.empty()) {
+    // We can't read the code to detect the language if there's no
+    // file name, so leave Code empty here.
+    FileName = AssumeFileName;
+  } else {
+    // Read in the code in case the filename alone isn't enough to
+    // detect the language.
+    ErrorOr<std::unique_ptr<MemoryBuffer>> CodeOrErr =
+        MemoryBuffer::getFileOrSTDIN(FileNames[0]);
+    if (std::error_code EC = CodeOrErr.getError()) {
+      llvm::errs() << EC.message() << "\n";
+      return 1;
+    }
+    FileName = (FileNames[0] == "-") ? AssumeFileName : FileNames[0];
+    Code = std::move(CodeOrErr.get());
+  }
+  llvm::Expected<clang::format::FormatStyle> FormatStyle =
+      clang::format::getStyle(Style, FileName, FallbackStyle,
+                              Code ? Code->getBuffer() : "");
+  if (!FormatStyle) {
+    llvm::errs() << llvm::toString(FormatStyle.takeError()) << "\n";
+    return 1;
+  }
+  std::string Config = clang::format::configurationAsText(*FormatStyle);
+  outs() << Config << "\n";
+  return 0;
+}
+
+int main(int argc, const char **argv) {
+  llvm::InitLLVM X(argc, argv);
+
+  cl::HideUnrelatedOptions(ClangFormatPlusPlusCategory);
+
+  cl::SetVersionPrinter(PrintVersion);
+  cl::ParseCommandLineOptions(
+      argc, argv,
+      "A tool to format C/C++/Java/JavaScript/JSON/Objective-C/Protobuf/C# "
+      "code.\n\n"
+      "If no arguments are specified, it formats the code from standard input\n"
+      "and writes the result to the standard output.\n"
+      "If <file>s are given, it reformats the files. If -i is specified\n"
+      "together with <file>s, the files are edited in-place. Otherwise, the\n"
+      "result is written to the standard output.\n");
+
+  if (Help) {
+    cl::PrintHelpMessage();
+    return 0;
+  }
+
+  if (DumpConfig) {
+    return dumpConfig();
+  }
+
+  bool Error = false;
+  if (FileNames.empty()) {
+    Error = clang::format::format("-");
+    return Error ? 1 : 0;
+  }
+  if (FileNames.size() != 1 &&
+      (!Offsets.empty() || !Lengths.empty() || !LineRanges.empty())) {
+    errs() << "error: -offset, -length and -lines can only be used for "
+              "single file.\n";
+    return 1;
+  }
+  for (const auto &FileName : FileNames) {
+    if (Verbose)
+      errs() << "Formatting " << FileName << "\n";
+    Error |= clang::format::format(FileName);
+  }
+  return Error ? 1 : 0;
+}

clang/unittests/Format/FormatTest.cpp

protected:
   std::string format(llvm::StringRef Code,
                      const FormatStyle &Style = getLLVMStyle(),
                      StatusCheck CheckComplete = SC_ExpectComplete) {
     LLVM_DEBUG(llvm::errs() << "---\n");
     LLVM_DEBUG(llvm::errs() << Code << "\n\n");
     std::vector<tooling::Range> Ranges(1, tooling::Range(0, Code.size()));
     FormattingAttemptStatus Status;
     tooling::Replacements Replaces =
-        reformat(Style, Code, Ranges, "<stdin>", &Status);
+        reformat(Style, Code, Ranges, "<stdin>", &Status, true);
     if (CheckComplete != SC_DoNotCheck) {
       bool ExpectedCompleteFormat = CheckComplete == SC_ExpectComplete;
       EXPECT_EQ(ExpectedCompleteFormat, Status.FormatComplete)
           << Code << "\n\n";
     }
     ReplacementCount = Replaces.size();
     auto Result = applyAllReplacements(Code, Replaces);
     EXPECT_TRUE(static_cast<bool>(Result));
TEST_F(FormatTest, ParsesConfiguration) {
   CHECK_PARSE("PenaltyReturnTypeOnItsOwnLine: 1234",
               PenaltyReturnTypeOnItsOwnLine, 1234u);
   CHECK_PARSE("SpacesBeforeTrailingComments: 1234",
               SpacesBeforeTrailingComments, 1234u);
   CHECK_PARSE("IndentWidth: 32", IndentWidth, 32u);
   CHECK_PARSE("ContinuationIndentWidth: 11", ContinuationIndentWidth, 11u);
   CHECK_PARSE("CommentPragmas: '// abc$'", CommentPragmas, "// abc$");
 
+  Style.ConstPlacement = FormatStyle::CS_West;
+  CHECK_PARSE("ConstPlacement: Leave", ConstPlacement, FormatStyle::CS_Leave);
+  CHECK_PARSE("ConstPlacement: East", ConstPlacement, FormatStyle::CS_East);
+  CHECK_PARSE("ConstPlacement: West", ConstPlacement, FormatStyle::CS_West);
+  CHECK_PARSE("ConstPlacement: Right", ConstPlacement, FormatStyle::CS_East);
+  CHECK_PARSE("ConstPlacement: Left", ConstPlacement, FormatStyle::CS_West);
+
   Style.AlignConsecutiveAssignments = FormatStyle::ACS_Consecutive;
   CHECK_PARSE("AlignConsecutiveAssignments: None", AlignConsecutiveAssignments,
               FormatStyle::ACS_None);
   CHECK_PARSE("AlignConsecutiveAssignments: Consecutive",
               AlignConsecutiveAssignments, FormatStyle::ACS_Consecutive);
   CHECK_PARSE("AlignConsecutiveAssignments: AcrossEmptyLines",
               AlignConsecutiveAssignments, FormatStyle::ACS_AcrossEmptyLines);
   CHECK_PARSE("AlignConsecutiveAssignments: AcrossEmptyLinesAndComments",
constexpr StringRef Code =
       "  // We already did this with multi line comments and strings. Just to "
       "check if everything is working.\n"
       "  const std::string SmallString = \"Hello World\";\n"
       "  // Small line comment\n"
       "  return String.size() > SmallString.size();\n"
       "}";
   EXPECT_EQ(Code, format(Code, Style));
 }
+
+TEST_F(FormatTest, EastWestConst) {
+  FormatStyle Style = getLLVMStyle();
+
+  // keep the const style unaltered
+  verifyFormat("const int a;", Style);
+  verifyFormat("const int *a;", Style);
+  verifyFormat("const int &a;", Style);
+  verifyFormat("const int &&a;", Style);
+  verifyFormat("int const b;", Style);
+  verifyFormat("int const *b;", Style);
+  verifyFormat("int const &b;", Style);
+  verifyFormat("int const &&b;", Style);
+  verifyFormat("int const *b const;", Style);
+  verifyFormat("int *const c;", Style);
+
+  verifyFormat("const Foo a;", Style);
+  verifyFormat("const Foo *a;", Style);
+  verifyFormat("const Foo &a;", Style);
+  verifyFormat("const Foo &&a;", Style);
+  verifyFormat("Foo const b;", Style);
+  verifyFormat("Foo const *b;", Style);
+  verifyFormat("Foo const &b;", Style);
+  verifyFormat("Foo const &&b;", Style);
+  verifyFormat("Foo const *b const;", Style);
+
+  verifyFormat("LLVM_NODISCARD const int &Foo();", Style);
+  verifyFormat("LLVM_NODISCARD int const &Foo();", Style);
+
+  verifyFormat("volatile const int *restrict;", Style);
+  verifyFormat("const volatile int *restrict;", Style);
+  verifyFormat("const int volatile *restrict;", Style);
+}
+
+TEST_F(FormatTest, EastConst) {
+  FormatStyle Style = getLLVMStyle();
+  Style.ConstPlacement = FormatStyle::CS_East;
+
+  verifyFormat("int const a;", Style);
+  verifyFormat("int const *a;", Style);
+  verifyFormat("int const &a;", Style);
+  verifyFormat("int const &&a;", Style);
+  verifyFormat("int const b;", Style);
+  verifyFormat("int const *b;", Style);
+  verifyFormat("int const &b;", Style);
+  verifyFormat("int const &&b;", Style);
+  verifyFormat("int const *b const;", Style);
+  verifyFormat("int *const c;", Style);
+
+  verifyFormat("Foo const a;", Style);
+  verifyFormat("Foo const *a;", Style);
+  verifyFormat("Foo const &a;", Style);
+  verifyFormat("Foo const &&a;", Style);
+  verifyFormat("Foo const b;", Style);
+  verifyFormat("Foo const *b;", Style);
+  verifyFormat("Foo const &b;", Style);
+  verifyFormat("Foo const &&b;", Style);
+  verifyFormat("Foo const *b const;", Style);
+  verifyFormat("Foo *const b;", Style);
+  verifyFormat("Foo const *const b;", Style);
+  verifyFormat("auto const v = get_value();", Style);
+  verifyFormat("long long const &a;", Style);
+  verifyFormat("unsigned char const *a;", Style);
+  verifyFormat("int main(int const argc, char const *const *const argv)",
+               Style);
+
+  verifyFormat("LLVM_NODISCARD int const &Foo();", Style);
+  verifyFormat("SourceRange getSourceRange() const override LLVM_READONLY",
+               Style);
+  verifyFormat("void foo() const override;", Style);
+  verifyFormat("void foo() const override LLVM_READONLY;", Style);
+  verifyFormat("void foo() const final;", Style);
+  verifyFormat("void foo() const final LLVM_READONLY;", Style);
+  verifyFormat("void foo() const LLVM_READONLY;", Style);
+
+  verifyFormat(
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      Style);
+  verifyFormat(
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      "template <typename Func> explicit Action(const Action<Func>& action);",
+      Style);
+  verifyFormat(
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      "template <typename Func>\nexplicit Action(const Action<Func>& action);",
+      Style);
+
+  verifyFormat("int const a;", "const int a;", Style);
+  verifyFormat("int const *a;", "const int *a;", Style);
+  verifyFormat("int const &a;", "const int &a;", Style);
+  verifyFormat("foo(int const &a)", "foo(const int &a)", Style);
+  verifyFormat("unsigned char *a;", "unsigned char *a;", Style);
+  verifyFormat("unsigned char const *a;", "const unsigned char *a;", Style);
+  verifyFormat("vector<int, int const, int &, int const &> args1",
+               "vector<int, const int, int &, const int &> args1", Style);
+  verifyFormat("unsigned int const &get_nu() const",
+               "const unsigned int &get_nu() const", Style);
+  verifyFormat("Foo<int> const &a", "const Foo<int> &a", Style);
+  verifyFormat("Foo<int>::iterator const &a", "const Foo<int>::iterator &a",
+               Style);
+
+  verifyFormat("Foo(int a, "
+               "unsigned b, // c-style args\n"
+               "    Bar const &c);",
+               "Foo(int a, "
+               "unsigned b, // c-style args\n"
+               "    const Bar &c);",
+               Style);
+
+  verifyFormat("volatile int const;", "volatile const int;", Style);
+  verifyFormat("volatile int const;", "const volatile int;", Style);
+  verifyFormat("int volatile const;", "const int volatile;", Style);
+  verifyFormat("volatile int const *restrict;", "volatile const int *restrict;",
+               Style);
+  verifyFormat("volatile int const *restrict;", "const volatile int *restrict;",
+               Style);
+  verifyFormat("int volatile const *restrict;", "const int volatile *restrict;",
+               Style);
+
+  verifyFormat("static int const bat;", "static const int bat;", Style);
+  verifyFormat("static int const bat;", "static int const bat;", Style);
+
+  verifyFormat("int const Foo<int>::bat = 0;", "const int Foo<int>::bat = 0;",
+               Style);
+  verifyFormat("int const Foo<int>::bat = 0;", "int const Foo<int>::bat = 0;",
+               Style);
+  verifyFormat("void fn(Foo<T> const &i);", "void fn(const Foo<T> &i);", Style);
+  verifyFormat("int const Foo<int>::fn() {", "int const Foo<int>::fn() {",
+               Style);
+  verifyFormat("Foo<Foo<int>> const *p;", "const Foo<Foo<int>> *p;", Style);
+  verifyFormat(
+      "Foo<Foo<int>> const *p = const_cast<Foo<Foo<int>> const *>(&ffi);",
+      "const Foo<Foo<int>> *p = const_cast<const Foo<Foo<int>> *>(&ffi);",
+      Style);
+
+  verifyFormat("void fn(Foo<T> const &i);", "void fn(const Foo<T> &i);", Style);
+  verifyFormat("void fns(ns::S const &s);", "void fns(const ns::S &s);", Style);
+  verifyFormat("void fn(ns::Foo<T> const &i);", "void fn(const ns::Foo<T> &i);",
+               Style);
+  verifyFormat("void fns(ns::ns2::S const &s);",
+               "void fns(const ns::ns2::S &s);", Style);
+  verifyFormat("void fn(ns::Foo<Bar<T>> const &i);",
+               "void fn(const ns::Foo<Bar<T>> &i);", Style);
+  verifyFormat("void fn(ns::ns2::Foo<Bar<T>> const &i);",
+               "void fn(const ns::ns2::Foo<Bar<T>> &i);", Style);
+  verifyFormat("void fn(ns::ns2::Foo<Bar<T, U>> const &i);",
+               "void fn(const ns::ns2::Foo<Bar<T, U>> &i);", Style);
+
+  verifyFormat("LocalScope const *Scope = nullptr;",
+               "const LocalScope* Scope = nullptr;", Style);
+  verifyFormat("struct DOTGraphTraits<Stmt const *>",
+               "struct DOTGraphTraits<const Stmt *>", Style);
+
+  verifyFormat(
+      "bool tools::addXRayRuntime(ToolChain const &TC, ArgList const &Args) {",
+      "bool tools::addXRayRuntime(const ToolChain&TC, const ArgList &Args) {",
+      Style);
+  verifyFormat("Foo<Foo<int> const> P;", "Foo<const Foo<int>> P;", Style);
+  verifyFormat("Foo<Foo<int> const> P;\n", "Foo<const Foo<int>> P;\n", Style);
+  verifyFormat("Foo<Foo<int> const> P;\n#if 0\n#else\n#endif",
+               "Foo<const Foo<int>> P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("auto const i = 0;", "const auto i = 0;", Style);
+  verifyFormat("auto const &ir = i;", "const auto &ir = i;", Style);
+  verifyFormat("auto const *ip = &i;", "const auto *ip = &i;", Style);
+
+  verifyFormat("Foo<Foo<int> const> P;\n#if 0\n#else\n#endif",
+               "Foo<const Foo<int>> P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("Bar<Bar<int const> const> P;\n#if 0\n#else\n#endif",
+               "Bar<Bar<const int> const> P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("Baz<Baz<int const> const> P;\n#if 0\n#else\n#endif",
+               "Baz<const Baz<const int>> P;\n#if 0\n#else\n#endif", Style);
+
+  // verifyFormat("#if 0\nBoo<Boo<int const> const> P;\n#else\n#endif",
+  //             "#if 0\nBoo<const Boo<const int>> P;\n#else\n#endif", Style);
+
+  verifyFormat("int const P;\n#if 0\n#else\n#endif",
+               "const int P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("unsigned long const a;", "const unsigned long a;", Style);
+  verifyFormat("unsigned long long const a;", "const unsigned long long a;",
+               Style);
+
+  // don't adjust macros
+  verifyFormat("const INTPTR a;", "const INTPTR a;", Style);
+}
+
+TEST_F(FormatTest, WestConst) {
+  FormatStyle Style = getLLVMStyle();
+  Style.ConstPlacement = FormatStyle::CS_West;
+
+  verifyFormat("const int a;", Style);
+  verifyFormat("const int *a;", Style);
+  verifyFormat("const int &a;", Style);
+  verifyFormat("const int &&a;", Style);
+  verifyFormat("const int b;", Style);
+  verifyFormat("const int *b;", Style);
+  verifyFormat("const int &b;", Style);
+  verifyFormat("const int &&b;", Style);
+  verifyFormat("const int *b const;", Style);
+  verifyFormat("int *const c;", Style);
+
+  verifyFormat("const Foo a;", Style);
+  verifyFormat("const Foo *a;", Style);
+  verifyFormat("const Foo &a;", Style);
+  verifyFormat("const Foo &&a;", Style);
+  verifyFormat("const Foo b;", Style);
+  verifyFormat("const Foo *b;", Style);
+  verifyFormat("const Foo &b;", Style);
+  verifyFormat("const Foo &&b;", Style);
+  verifyFormat("const Foo *b const;", Style);
+  verifyFormat("Foo *const b;", Style);
+  verifyFormat("const Foo *const b;", Style);
+
+  verifyFormat("LLVM_NODISCARD const int &Foo();", Style);
+
+  verifyFormat("const char a[];", Style);
+  verifyFormat("const auto v = get_value();", Style);
+  verifyFormat("const long long &a;", Style);
+  verifyFormat("const unsigned char *a;", Style);
+  verifyFormat("const unsigned char *a;", "unsigned char const *a;", Style);
+  verifyFormat("const Foo<int> &a", "Foo<int> const &a", Style);
+  verifyFormat("const Foo<int>::iterator &a", "Foo<int>::iterator const &a",
+               Style);
+
+  verifyFormat("const int a;", "int const a;", Style);
+  verifyFormat("const int *a;", "int const *a;", Style);
+  verifyFormat("const int &a;", "int const &a;", Style);
+  verifyFormat("foo(const int &a)", "foo(int const &a)", Style);
+  verifyFormat("unsigned char *a;", "unsigned char *a;", Style);
+  verifyFormat("const unsigned int &get_nu() const",
+               "unsigned int const &get_nu() const", Style);
+
+  verifyFormat("const volatile int;", "volatile const int;", Style);
+  verifyFormat("const volatile int;", "const volatile int;", Style);
+  verifyFormat("const int volatile;", "const int volatile;", Style);
+
+  verifyFormat("const volatile int *restrict;", "volatile const int *restrict;",
+               Style);
+  verifyFormat("const volatile int *restrict;", "const volatile int *restrict;",
+               Style);
+  verifyFormat("const int volatile *restrict;", "const int volatile *restrict;",
+               Style);
+
+  verifyFormat("SourceRange getSourceRange() const override LLVM_READONLY;",
+               Style);
+
+  verifyFormat("void foo() const override;", Style);
+  verifyFormat("void foo() const override LLVM_READONLY;", Style);
+  verifyFormat("void foo() const final;", Style);
+  verifyFormat("void foo() const final LLVM_READONLY;", Style);
+  verifyFormat("void foo() const LLVM_READONLY;", Style);
+
+  verifyFormat(
+      "template <typename Func> explicit Action(const Action<Func> &action);",
+      Style);
+  verifyFormat(
+      "template <typename Func> explicit Action(const Action<Func> &action);",
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      Style);
+
+  verifyFormat("static const int bat;", "static const int bat;", Style);
+  verifyFormat("static const int bat;", "static int const bat;", Style);
+
+  verifyFormat("static const int Foo<int>::bat = 0;",
+               "static const int Foo<int>::bat = 0;", Style);
+  verifyFormat("static const int Foo<int>::bat = 0;",
+               "static int const Foo<int>::bat = 0;", Style);
+
+  verifyFormat("void fn(const Foo<T> &i);");
+
+  verifyFormat("const int Foo<int>::bat = 0;", "const int Foo<int>::bat = 0;",
+               Style);
+  verifyFormat("const int Foo<int>::bat = 0;", "int const Foo<int>::bat = 0;",
+               Style);
+  verifyFormat("void fn(const Foo<T> &i);", "void fn( Foo<T> const &i);",
+               Style);
+  verifyFormat("const int Foo<int>::fn() {", "int const Foo<int>::fn() {",
+               Style);
+  verifyFormat("const Foo<Foo<int>> *p;", "Foo<Foo<int>> const *p;", Style);
+  verifyFormat(
+      "const Foo<Foo<int>> *p = const_cast<const Foo<Foo<int>> *>(&ffi);",
+      "const Foo<Foo<int>> *p = const_cast<Foo<Foo<int>> const *>(&ffi);",
+      Style);
+
+  verifyFormat("void fn(const Foo<T> &i);", "void fn(Foo<T> const &i);", Style);
+  verifyFormat("void fns(const ns::S &s);", "void fns(ns::S const &s);", Style);
+  verifyFormat("void fn(const ns::Foo<T> &i);", "void fn(ns::Foo<T> const &i);",
+               Style);
+  verifyFormat("void fns(const ns::ns2::S &s);",
+               "void fns(ns::ns2::S const &s);", Style);
+  verifyFormat("void fn(const ns::Foo<Bar<T>> &i);",
+               "void fn(ns::Foo<Bar<T>> const &i);", Style);
+  verifyFormat("void fn(const ns::ns2::Foo<Bar<T>> &i);",
+               "void fn(ns::ns2::Foo<Bar<T>> const &i);", Style);
+  verifyFormat("void fn(const ns::ns2::Foo<Bar<T, U>> &i);",
+               "void fn(ns::ns2::Foo<Bar<T, U>> const &i);", Style);
+
+  verifyFormat("const auto i = 0;", "auto const i = 0;", Style);
+  verifyFormat("const auto &ir = i;", "auto const &ir = i;", Style);
+  verifyFormat("const auto *ip = &i;", "auto const *ip = &i;", Style);
+
+  verifyFormat("Foo<const Foo<int>> P;\n#if 0\n#else\n#endif",
+               "Foo<Foo<int> const> P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("Foo<Foo<const int>> P;\n#if 0\n#else\n#endif",
+               "Foo<Foo<int const>> P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("const int P;\n#if 0\n#else\n#endif",
+               "int const P;\n#if 0\n#else\n#endif", Style);
+
+  verifyFormat("const unsigned long a;", "unsigned long const a;", Style);
+  verifyFormat("const unsigned long long a;", "unsigned long long const a;",
+               Style);
+
+  verifyFormat("const long long unsigned a;", "long const long unsigned a;",
+               Style);
+
+  // don't adjust macros
+  verifyFormat("INTPTR const a;", "INTPTR const a;", Style);
+}
+
 } // namespace
 } // namespace format
 } // namespace clang