MyDeveloperDay updated this revision to Diff 230124.
MyDeveloperDay added a comment.

-update with missing files
-clang-format test


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69764/new/

https://reviews.llvm.org/D69764

Files:
  clang/docs/ClangFormatStyleOptions.rst
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Format/Format.h
  clang/lib/Format/CMakeLists.txt
  clang/lib/Format/EastWestConstFixer.cpp
  clang/lib/Format/EastWestConstFixer.h
  clang/lib/Format/Format.cpp
  clang/tools/clang-format/ClangFormat.cpp
  clang/unittests/Format/FormatTest.cpp

Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -27,6 +27,10 @@
 
 FormatStyle getGoogleStyle() { return getGoogleStyle(FormatStyle::LK_Cpp); }
 
+#define VERIFYFORMAT(expect, style) verifyFormat(expect, style, __LINE__)
+#define VERIFYFORMAT2(expect, actual, style)                                   \
+  verifyFormat(expect, actual, style, __LINE__)
+
 class FormatTest : public ::testing::Test {
 protected:
   enum StatusCheck { SC_ExpectComplete, SC_ExpectIncomplete, SC_DoNotCheck };
@@ -66,10 +70,12 @@
   }
 
   void verifyFormat(llvm::StringRef Expected, llvm::StringRef Code,
-                    const FormatStyle &Style = getLLVMStyle()) {
+                    const FormatStyle &Style = getLLVMStyle(),
+                    int line = __LINE__) {
     EXPECT_EQ(Expected.str(), format(Expected, Style))
-        << "Expected code is not stable";
-    EXPECT_EQ(Expected.str(), format(Code, Style));
+        << "Expected code is not stable at " << __FILE__ << ":" << line;
+    EXPECT_EQ(Expected.str(), format(Code, Style))
+        << " at " << __FILE__ << ":" << line;
     if (Style.Language == FormatStyle::LK_Cpp) {
       // Objective-C++ is a superset of C++, so everything checked for C++
       // needs to be checked for Objective-C++ as well.
@@ -80,8 +86,9 @@
   }
 
   void verifyFormat(llvm::StringRef Code,
-                    const FormatStyle &Style = getLLVMStyle()) {
-    verifyFormat(Code, test::messUp(Code), Style);
+                    const FormatStyle &Style = getLLVMStyle(),
+                    int line = __LINE__) {
+    verifyFormat(Code, test::messUp(Code), Style, line);
   }
 
   void verifyIncompleteFormat(llvm::StringRef Code,
@@ -12609,6 +12616,15 @@
   CHECK_PARSE("ContinuationIndentWidth: 11", ContinuationIndentWidth, 11u);
   CHECK_PARSE("CommentPragmas: '// abc$'", CommentPragmas, "// abc$");
 
+  Style.ConstStyle = FormatStyle::CS_Left;
+  CHECK_PARSE("ConstStyle: Leave", ConstStyle, FormatStyle::CS_Leave);
+  CHECK_PARSE("ConstStyle: East", ConstStyle, FormatStyle::CS_Right);
+  CHECK_PARSE("ConstStyle: West", ConstStyle, FormatStyle::CS_Left);
+  CHECK_PARSE("ConstStyle: Right", ConstStyle, FormatStyle::CS_Right);
+  CHECK_PARSE("ConstStyle: Left", ConstStyle, FormatStyle::CS_Left);
+  CHECK_PARSE("ConstStyle: After", ConstStyle, FormatStyle::CS_Right);
+  CHECK_PARSE("ConstStyle: Before", ConstStyle, FormatStyle::CS_Left);
+
   Style.PointerAlignment = FormatStyle::PAS_Middle;
   CHECK_PARSE("PointerAlignment: Left", PointerAlignment,
               FormatStyle::PAS_Left);
@@ -14994,6 +15010,194 @@
   verifyFormat("operator&&(int(&&)(), class Foo);", 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);
+
+  Style.ConstStyle = FormatStyle::CS_Right;
+
+  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);
+  VERIFYFORMAT2(
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      "template <typename Func> explicit Action(const Action<Func>& action);",
+      Style);
+  VERIFYFORMAT2(
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      "template <typename Func>\nexplicit Action(const Action<Func>& action);",
+      Style);
+
+  VERIFYFORMAT2("int const a;", "const int a;", Style);
+  VERIFYFORMAT2("int const *a;", "const int *a;", Style);
+  VERIFYFORMAT2("int const &a;", "const int &a;", Style);
+  VERIFYFORMAT2("foo(int const &a)", "foo(const int &a)", Style);
+  VERIFYFORMAT2("unsigned char *a;", "unsigned char *a;", Style);
+  VERIFYFORMAT2("unsigned char const *a;", "const unsigned char *a;", Style);
+  VERIFYFORMAT2("vector<int, int const, int &, int const &> args1",
+                "vector<int, const int, int &, const int &> args1", Style);
+  VERIFYFORMAT2("unsigned int const &get_nu() const",
+                "const unsigned int &get_nu() const", Style);
+  VERIFYFORMAT2("Foo<int> const &a", "const Foo<int> &a", Style);
+  VERIFYFORMAT2("Foo<int>::iterator const &a", "const Foo<int>::iterator &a",
+                Style);
+
+  VERIFYFORMAT2("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);
+
+  VERIFYFORMAT2("volatile int const;", "volatile const int;", Style);
+  VERIFYFORMAT2("volatile int const;", "const volatile int;", Style);
+  VERIFYFORMAT2("int volatile const;", "const int volatile;", Style);
+  VERIFYFORMAT2("volatile int const *restrict;",
+                "volatile const int *restrict;", Style);
+  VERIFYFORMAT2("volatile int const *restrict;",
+                "const volatile int *restrict;", Style);
+  VERIFYFORMAT2("int volatile const *restrict;",
+                "const int volatile *restrict;", Style);
+
+  Style.ConstStyle = FormatStyle::CS_Left;
+
+  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);
+  VERIFYFORMAT2("const unsigned char *a;", "unsigned char const *a;", Style);
+  VERIFYFORMAT2("const Foo<int> &a", "Foo<int> const &a", Style);
+  VERIFYFORMAT2("const Foo<int>::iterator &a", "Foo<int>::iterator const &a",
+                Style);
+
+  VERIFYFORMAT2("const int a;", "int const a;", Style);
+  VERIFYFORMAT2("const int *a;", "int const *a;", Style);
+  VERIFYFORMAT2("const int &a;", "int const &a;", Style);
+  VERIFYFORMAT2("foo(const int &a)", "foo(int const &a)", Style);
+  VERIFYFORMAT2("unsigned char *a;", "unsigned char *a;", Style);
+  VERIFYFORMAT2("const unsigned int &get_nu() const",
+                "unsigned int const &get_nu() const", Style);
+
+  VERIFYFORMAT2("volatile const int;", "volatile const int;", Style);
+  VERIFYFORMAT2("const volatile int;", "const volatile int;", Style);
+  VERIFYFORMAT2("const int volatile;", "const int volatile;", Style);
+
+  VERIFYFORMAT2("volatile const int *restrict;",
+                "volatile const int *restrict;", Style);
+  VERIFYFORMAT2("const volatile int *restrict;",
+                "const volatile int *restrict;", Style);
+  VERIFYFORMAT2("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);
+  VERIFYFORMAT2(
+      "template <typename Func> explicit Action(const Action<Func> &action);",
+      "template <typename Func> explicit Action(Action<Func> const &action);",
+      Style);
+}
+
 } // namespace
 } // namespace format
 } // namespace clang
Index: clang/tools/clang-format/ClangFormat.cpp
===================================================================
--- clang/tools/clang-format/ClangFormat.cpp
+++ clang/tools/clang-format/ClangFormat.cpp
@@ -19,6 +19,7 @@
 #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"
@@ -104,6 +105,12 @@
              "SortIncludes style flag"),
     cl::cat(ClangFormatCategory));
 
+static cl::opt<std::string> ConstStyle(
+    "const-style",
+    cl::desc("If set, overrides the const style behavior determined by the "
+             "ConstStyle style flag"),
+    cl::init(""), cl::cat(ClangFormatCategory));
+
 static cl::opt<bool>
     Verbose("verbose", cl::desc("If set, shows the list of processed files"),
             cl::cat(ClangFormatCategory));
@@ -384,6 +391,14 @@
     return true;
   }
 
+  StringRef ConstAlignment = ConstStyle;
+
+  FormatStyle->ConstStyle =
+      StringSwitch<FormatStyle::ConstAlignmentStyle>(ConstAlignment.lower())
+          .Cases("right", "east", "after", FormatStyle::CS_Right)
+          .Cases("left", "west", "before", FormatStyle::CS_Left)
+          .Default(FormatStyle->ConstStyle);
+
   if (SortIncludes.getNumOccurrences() != 0)
     FormatStyle->SortIncludes = SortIncludes;
   unsigned CursorPosition = Cursor;
Index: clang/lib/Format/Format.cpp
===================================================================
--- clang/lib/Format/Format.cpp
+++ clang/lib/Format/Format.cpp
@@ -15,6 +15,7 @@
 #include "clang/Format/Format.h"
 #include "AffectedRangeManager.h"
 #include "ContinuationIndenter.h"
+#include "EastWestConstFixer.h"
 #include "FormatInternal.h"
 #include "FormatTokenLexer.h"
 #include "NamespaceEndCommentsFixer.h"
@@ -114,6 +115,20 @@
   }
 };
 
+template <> struct ScalarEnumerationTraits<FormatStyle::ConstAlignmentStyle> {
+  static void enumeration(IO &IO, FormatStyle::ConstAlignmentStyle &Value) {
+    IO.enumCase(Value, "Leave", FormatStyle::CS_Leave);
+    IO.enumCase(Value, "Left", FormatStyle::CS_Left);
+    IO.enumCase(Value, "Right", FormatStyle::CS_Right);
+
+    // Other allowed names following community conventions.
+    IO.enumCase(Value, "Before", FormatStyle::CS_Left);
+    IO.enumCase(Value, "After", FormatStyle::CS_Right);
+    IO.enumCase(Value, "East", FormatStyle::CS_Right);
+    IO.enumCase(Value, "West", FormatStyle::CS_Left);
+  }
+};
+
 template <> struct ScalarEnumerationTraits<FormatStyle::ShortFunctionStyle> {
   static void enumeration(IO &IO, FormatStyle::ShortFunctionStyle &Value) {
     IO.enumCase(Value, "None", FormatStyle::SFS_None);
@@ -460,6 +475,7 @@
     IO.mapOptional("BreakStringLiterals", Style.BreakStringLiterals);
     IO.mapOptional("ColumnLimit", Style.ColumnLimit);
     IO.mapOptional("CommentPragmas", Style.CommentPragmas);
+    IO.mapOptional("ConstStyle", Style.ConstStyle);
     IO.mapOptional("CompactNamespaces", Style.CompactNamespaces);
     IO.mapOptional("ConstructorInitializerAllOnOneLineOrOnePerLine",
                    Style.ConstructorInitializerAllOnOneLineOrOnePerLine);
@@ -761,6 +777,7 @@
   LLVMStyle.BreakStringLiterals = true;
   LLVMStyle.ColumnLimit = 80;
   LLVMStyle.CommentPragmas = "^ IWYU pragma:";
+  LLVMStyle.ConstStyle = FormatStyle::CS_Leave;
   LLVMStyle.CompactNamespaces = false;
   LLVMStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = false;
   LLVMStyle.ConstructorInitializerIndentWidth = 4;
@@ -939,6 +956,7 @@
     // taze:, triple slash directives (`/// <...`), @see, which is commonly
     // followed by overlong URLs.
     GoogleStyle.CommentPragmas = "(taze:|^/[ \t]*<|@see)";
+    GoogleStyle.ConstStyle = FormatStyle::CS_Leave;
     GoogleStyle.MaxEmptyLinesToKeep = 3;
     GoogleStyle.NamespaceIndentation = FormatStyle::NI_All;
     GoogleStyle.SpacesInContainerLiterals = false;
@@ -990,6 +1008,7 @@
   //   _prepend that with a comment_ to prevent it" before changing behavior.
   ChromiumStyle.IncludeStyle.IncludeBlocks =
       tooling::IncludeStyle::IBS_Preserve;
+  ChromiumStyle.ConstStyle = FormatStyle::CS_Leave;
 
   if (Language == FormatStyle::LK_Java) {
     ChromiumStyle.AllowShortIfStatementsOnASingleLine =
@@ -1051,6 +1070,7 @@
   MozillaStyle.PenaltyReturnTypeOnItsOwnLine = 200;
   MozillaStyle.PointerAlignment = FormatStyle::PAS_Left;
   MozillaStyle.SpaceAfterTemplateKeyword = false;
+  MozillaStyle.ConstStyle = FormatStyle::CS_Leave;
   return MozillaStyle;
 }
 
@@ -1074,6 +1094,7 @@
   Style.PointerAlignment = FormatStyle::PAS_Left;
   Style.SpaceBeforeCpp11BracedList = true;
   Style.SpaceInEmptyBlock = true;
+  Style.ConstStyle = FormatStyle::CS_Leave;
   return Style;
 }
 
@@ -1089,6 +1110,7 @@
   Style.FixNamespaceComments = false;
   Style.SpaceBeforeParens = FormatStyle::SBPO_Always;
   Style.Standard = FormatStyle::LS_Cpp03;
+  Style.ConstStyle = FormatStyle::CS_Leave;
   return Style;
 }
 
@@ -1116,6 +1138,7 @@
   Style.AllowShortLoopsOnASingleLine = false;
   Style.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
   Style.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
+  Style.ConstStyle = FormatStyle::CS_Leave;
   return Style;
 }
 
@@ -1124,6 +1147,7 @@
   NoStyle.DisableFormat = true;
   NoStyle.SortIncludes = false;
   NoStyle.SortUsingDeclarations = false;
+  NoStyle.ConstStyle = FormatStyle::CS_Leave;
   return NoStyle;
 }
 
@@ -2418,6 +2442,13 @@
       });
   }
 
+  if (Style.isCpp() || Style.Language == FormatStyle::LK_ObjC) {
+    if (Style.ConstStyle != 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) {
Index: clang/lib/Format/EastWestConstFixer.h
===================================================================
--- /dev/null
+++ clang/lib/Format/EastWestConstFixer.h
@@ -0,0 +1,36 @@
+//===--- EastWwestConstFixer.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
Index: clang/lib/Format/EastWestConstFixer.cpp
===================================================================
--- /dev/null
+++ clang/lib/Format/EastWestConstFixer.cpp
@@ -0,0 +1,249 @@
+//===--- 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>
+
+#define DEBUG_TYPE "using-declarations-sorter"
+
+namespace clang {
+namespace format {
+
+static void removeToken(const SourceManager &SourceMgr,
+                        tooling::Replacements &Fixes,
+                        const FormatToken *First) {
+  // Change `const int` to be `int const`.
+  auto Range = CharSourceRange::getCharRange(First->getStartOfNonWhitespace(),
+                                             First->Tok.getEndLoc());
+
+  auto Err = Fixes.add(tooling::Replacement(SourceMgr, Range, ""));
+
+  if (Err) {
+    llvm::errs() << "Error while rearranging const : "
+                 << llvm::toString(std::move(Err)) << "\n";
+  }
+}
+
+static void insertConstAfter(const SourceManager &SourceMgr,
+                             tooling::Replacements &Fixes,
+                             const FormatToken *First) {
+  FormatToken *Next = First->Next;
+  if (!Next) {
+    return;
+  }
+  // Change `const int` to be `int const`.
+  auto Range = CharSourceRange::getCharRange(First->Tok.getEndLoc(),
+                                             Next->getStartOfNonWhitespace());
+
+  auto Err = Fixes.add(tooling::Replacement(SourceMgr, Range, " const "));
+
+  if (Err) {
+    llvm::errs() << "Error while rearranging const : "
+                 << llvm::toString(std::move(Err)) << "\n";
+  }
+}
+
+static void insertConstBefore(const SourceManager &SourceMgr,
+                              tooling::Replacements &Fixes,
+                              const FormatToken *First) {
+  // Change `const int` to be `int const`.
+  auto Range = CharSourceRange::getCharRange(
+      First->getStartOfNonWhitespace(), First->Next->getStartOfNonWhitespace());
+
+  std::string NewText = " const ";
+  NewText += First->TokenText;
+
+  auto Err = Fixes.add(tooling::Replacement(SourceMgr, Range, NewText));
+
+  if (Err) {
+    llvm::errs() << "Error while rearranging const : "
+                 << llvm::toString(std::move(Err)) << "\n";
+  }
+}
+
+static void swapFirstTwoTokens(const SourceManager &SourceMgr,
+                               tooling::Replacements &Fixes,
+                               const FormatToken *First,
+                               const FormatToken *Second) {
+  // Change `const int` to be `int const`.
+  std::string NewType = Second->TokenText;
+  NewType += " ";
+  NewType += First->TokenText;
+  auto Range = CharSourceRange::getCharRange(First->getStartOfNonWhitespace(),
+                                             Second->Tok.getEndLoc());
+
+  auto Err = Fixes.add(tooling::Replacement(SourceMgr, Range, NewType));
+
+  if (Err) {
+    llvm::errs() << "Error while rearranging const : "
+                 << llvm::toString(std::move(Err)) << "\n";
+  }
+}
+
+static void swapFirstThreeTokens(const SourceManager &SourceMgr,
+                                 tooling::Replacements &Fixes,
+                                 const FormatToken *First,
+                                 const FormatToken *Second,
+                                 const FormatToken *Third, bool West) {
+  // Change `const unsigned char` to be `unsigned char const`.
+  std::string NewType;
+  if (West) {
+    NewType = Third->TokenText;
+    NewType += " ";
+    NewType += First->TokenText;
+    NewType += " ";
+    NewType += Second->TokenText;
+  } else {
+    NewType = Second->TokenText;
+    NewType += " ";
+    NewType += Third->TokenText;
+    NewType += " ";
+    NewType += First->TokenText;
+  }
+
+  auto Range = CharSourceRange::getCharRange(First->getStartOfNonWhitespace(),
+                                             Third->Tok.getEndLoc());
+
+  auto Err = Fixes.add(tooling::Replacement(SourceMgr, Range, NewType));
+
+  if (Err) {
+    llvm::errs() << "Error while rearranging const : "
+                 << llvm::toString(std::move(Err)) << "\n";
+  }
+}
+
+static bool IsCVQualifierOrType(const FormatToken *Tok) {
+  if (!Tok)
+    return false;
+  return (Tok->isSimpleTypeSpecifier() || Tok->is(tok::kw_volatile));
+}
+
+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) {
+  const AdditionalKeywords &Keywords = Tokens.getKeywords();
+  const SourceManager &SourceMgr = Env.getSourceManager();
+  AffectedRangeMgr.computeAffectedLines(AnnotatedLines);
+  tooling::Replacements Fixes;
+  for (size_t I = 0, E = AnnotatedLines.size(); I != E; ++I) {
+    const auto *Tok = AnnotatedLines[I]->First;
+    const auto *Last = AnnotatedLines[I]->Last;
+
+    while (Tok && Tok != Last) {
+      if (!Tok->Next) {
+        break;
+      }
+      if (Tok->is(tok::comment)) {
+        Tok = Tok->Next;
+        continue;
+      }
+      if (Style.ConstStyle == FormatStyle::CS_Right) {
+        if (Tok->is(tok::kw_const) && IsCVQualifierOrType(Tok->Next) &&
+            Tok->Next->Next && IsCVQualifierOrType(Tok->Next->Next)) {
+          // The unsigned/signed case  `const unsigned int` -> `unsigned int
+          // const`
+          swapFirstThreeTokens(SourceMgr, Fixes, Tok, Tok->Next,
+                               Tok->Next->Next, /*West=*/false);
+          Tok = Tok->Next->Next;
+          continue;
+        } else if (Tok->is(tok::kw_const) &&
+                   Tok->Next->isSimpleTypeSpecifier()) {
+          // The basic case  `const int` -> `int const`
+          swapFirstTwoTokens(SourceMgr, Fixes, Tok, Tok->Next);
+
+        } else if (Tok->startsSequence(tok::kw_const, tok::identifier)) {
+          // The case  `const Foo` -> `Foo const`
+          // The case  `const Foo *` -> `Foo const *`
+          if (Tok->Next->Next &&
+              Tok->Next->Next->isOneOf(tok::identifier, tok::star, tok::amp,
+                                       tok::ampamp) &&
+              !Tok->Next->isOneOf(Keywords.kw_override, Keywords.kw_final)) {
+            swapFirstTwoTokens(SourceMgr, Fixes, Tok, Tok->Next);
+          } else if (Tok->startsSequence(tok::kw_const, tok::identifier,
+                                         TT_TemplateOpener)) {
+            // Read from to the end of the TemplateOpener to
+            // TemplateCloser 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;
+              }
+              // remove the const
+              removeToken(SourceMgr, Fixes, Tok);
+              insertConstAfter(SourceMgr, Fixes, EndTemplate);
+            }
+          }
+        }
+      } else if (Style.ConstStyle == FormatStyle::CS_Left) {
+        if (IsCVQualifierOrType(Tok) && IsCVQualifierOrType(Tok->Next) &&
+            Tok->Next->Next && Tok->Next->Next->is(tok::kw_const)) {
+          // The unsigned/signed case  `unsigned int const` -> `const unsigned
+          // int`
+          swapFirstThreeTokens(SourceMgr, Fixes, Tok, Tok->Next,
+                               Tok->Next->Next, /*West=*/true);
+          Tok = Tok->Next->Next;
+          continue;
+        } else if (Tok->isSimpleTypeSpecifier() &&
+                   Tok->Next->is(tok::kw_const)) {
+          // The basic case  `int const` -> `const int`
+          swapFirstTwoTokens(SourceMgr, Fixes, Tok, Tok->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))) {
+              swapFirstTwoTokens(SourceMgr, Fixes, Tok, Tok->Next);
+            }
+          }
+        } else if (Tok->startsSequence(tok::identifier, TT_TemplateOpener)) {
+          // Read from to the end of the TemplateOpener to
+          // TemplateCloser const ArrayRef<int> a; const ArrayRef<int> &a;
+          FormatToken *EndTemplate = Tok->Next->MatchingParen;
+
+          // 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->is(tok::kw_const)) {
+            // remove the const
+            removeToken(SourceMgr, Fixes, EndTemplate->Next);
+            insertConstBefore(SourceMgr, Fixes, Tok);
+          }
+        }
+      }
+      Tok = Tok->Next;
+    }
+  }
+  return {Fixes, 0};
+}
+} // namespace format
+} // namespace clang
Index: clang/lib/Format/CMakeLists.txt
===================================================================
--- clang/lib/Format/CMakeLists.txt
+++ clang/lib/Format/CMakeLists.txt
@@ -14,6 +14,7 @@
   UnwrappedLineFormatter.cpp
   UnwrappedLineParser.cpp
   UsingDeclarationsSorter.cpp
+  EastWestConstFixer.cpp
   WhitespaceManager.cpp
 
   LINK_LIBS
Index: clang/include/clang/Format/Format.h
===================================================================
--- clang/include/clang/Format/Format.h
+++ clang/include/clang/Format/Format.h
@@ -1106,6 +1106,31 @@
   /// \endcode
   std::string CommentPragmas;
 
+  /// Different const alignment styles.
+  enum ConstAlignmentStyle {
+    /// Don't change const to either East const or West const.
+    /// \code
+    ///    int const a;
+    ///    const int *a;
+    /// \endcode
+    CS_Leave,
+    /// Change type decorations to be Left/Before/West const.
+    /// \code
+    ///    const int a;
+    ///    const int *a;
+    /// \endcode
+    CS_Left,
+    /// Change type decorations to be Right/After/East const.
+    /// \code
+    ///    int const a;
+    ///    int const *a;
+    /// \endcode
+    CS_Right
+  };
+
+  /// Different ways to arrange const.
+  ConstAlignmentStyle ConstStyle;
+
   /// Different ways to break inheritance list.
   enum BreakInheritanceListStyle {
     /// Break inheritance list before the colon and after the commas.
@@ -2089,6 +2114,7 @@
            BreakAfterJavaFieldAnnotations == R.BreakAfterJavaFieldAnnotations &&
            BreakStringLiterals == R.BreakStringLiterals &&
            ColumnLimit == R.ColumnLimit && CommentPragmas == R.CommentPragmas &&
+           ConstStyle == R.ConstStyle &&
            BreakInheritanceList == R.BreakInheritanceList &&
            ConstructorInitializerAllOnOneLineOrOnePerLine ==
                R.ConstructorInitializerAllOnOneLineOrOnePerLine &&
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -340,6 +340,10 @@
     const x = foo ?? default;
     const z = foo?.bar?.baz;
 
+- Option ``ConstStyle`` has been added auto-arrange the positioning of const
+  in variable and parameter declarations to be ``East`` const or ``West`` 
+  const .
+
 libclang
 --------
 
Index: clang/docs/ClangFormatStyleOptions.rst
===================================================================
--- clang/docs/ClangFormatStyleOptions.rst
+++ clang/docs/ClangFormatStyleOptions.rst
@@ -1375,6 +1375,37 @@
     namespace Extra {
     }}}
 
+**ConstStyle** (``ConstAlignmentStyle``)
+  Different ways to arrange const.
+
+  Possible values:
+
+  * ``CS_Leave`` (in configuration: ``Leave``)
+    Don't change const to either East const or West const.
+
+    .. code-block:: c++
+
+       int const a;
+       const int *a;
+
+  * ``CS_Left`` (in configuration: ``Left``)
+    Change type decorations to be Left/Before/West const.
+
+    .. code-block:: c++
+
+       const int a;
+       const int *a;
+
+  * ``CS_Right`` (in configuration: ``Right``)
+    Change type decorations to be Right/After/East 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.
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