Issue #958: Travis CI should enforce clang-format standards (#1026)

* Issue #958: Travis CI should enfore clang-format standards

This patch adds clang format support to the travis bots.

* Update path

* Roll back to version 8 since 9 is in test

* Cleanup clang

* Revert "Delete JSONCPP_DEPRECATED, use [[deprecated]] instead. (#978)" (#1029)

This reverts commit b27c83f691a03f521a1b3b99eefa2973f8e2bfcd.
diff --git a/.clang-format b/.clang-format
index 2a372fc..2a80669 100644
--- a/.clang-format
+++ b/.clang-format
@@ -1,47 +1,4 @@
----
-# BasedOnStyle:  LLVM
-AccessModifierOffset: -2
-ConstructorInitializerIndentWidth: 4
-AlignEscapedNewlinesLeft: false
-AlignTrailingComments: true
-AllowAllParametersOfDeclarationOnNextLine: true
-AllowShortIfStatementsOnASingleLine: false
-AllowShortLoopsOnASingleLine: false
-AlwaysBreakTemplateDeclarations: false
-AlwaysBreakBeforeMultilineStrings: false
-BreakBeforeBinaryOperators: false
-BreakBeforeTernaryOperators: true
-BreakConstructorInitializersBeforeComma: false
-BinPackParameters: false
-ColumnLimit:     80
-ConstructorInitializerAllOnOneLineOrOnePerLine: false
-DerivePointerBinding: false
-ExperimentalAutoDetectBinPacking: false
-IndentCaseLabels: false
-MaxEmptyLinesToKeep: 1
-NamespaceIndentation: None
-ObjCSpaceBeforeProtocolList: true
-PenaltyBreakBeforeFirstCallParameter: 19
-PenaltyBreakComment: 60
-PenaltyBreakString: 1000
-PenaltyBreakFirstLessLess: 120
-PenaltyExcessCharacter: 1000000
-PenaltyReturnTypeOnItsOwnLine: 60
-PointerBindsToType: true
-SpacesBeforeTrailingComments: 1
-Cpp11BracedListStyle: true
-Standard:        Cpp11
-IndentWidth:     2
-TabWidth:        8
-UseTab:          Never
-BreakBeforeBraces: Attach
-IndentFunctionDeclarationAfterType: false
-SpacesInParentheses: false
-SpacesInAngles:  false
-SpaceInEmptyParentheses: false
-SpacesInCStyleCastParentheses: false
-SpaceAfterControlStatementKeyword: true
-SpaceBeforeAssignmentOperators: true
-ContinuationIndentWidth: 4
-...
+BasedOnStyle:  LLVM
+DerivePointerAlignment: false
+PointerAlignment: Left
 
diff --git a/.travis.yml b/.travis.yml
index b649b46..a63929e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,6 +9,7 @@
 addons:
   homebrew:
     packages:
+    - clang-format
     - meson
     - ninja
     update: false # do not update homebrew by default
@@ -17,6 +18,7 @@
     - ubuntu-toolchain-r-test
     - llvm-toolchain-xenial-8
     packages:
+    - clang-format-8
     - clang-8
     - valgrind
 matrix:
@@ -25,7 +27,7 @@
   include:
     - name: Mac clang meson static release testing
       os: osx
-      osx_image: xcode10.2
+      osx_image: xcode11
       compiler: clang
       env:
          CXX="clang++"
diff --git a/.travis_scripts/meson_builder.sh b/.travis_scripts/meson_builder.sh
index dbf03cb..0820c89 100755
--- a/.travis_scripts/meson_builder.sh
+++ b/.travis_scripts/meson_builder.sh
@@ -63,9 +63,11 @@
 ninja --version
 _COMPILER_NAME=`basename ${CXX}`
 _BUILD_DIR_NAME="build-${BUILD_TYPE}_${LIB_TYPE}_${_COMPILER_NAME}"
+
+./.travis_scripts/run-clang-format.sh
 meson --buildtype ${BUILD_TYPE} --default-library ${LIB_TYPE} . "${_BUILD_DIR_NAME}"
 ninja -v -j 2 -C "${_BUILD_DIR_NAME}"
-#ninja -v -j 2 -C "${_BUILD_DIR_NAME}" test
+
 cd "${_BUILD_DIR_NAME}"
   meson test --no-rebuild --print-errorlogs
 
diff --git a/.travis_scripts/run-clang-format.py b/.travis_scripts/run-clang-format.py
new file mode 100755
index 0000000..68179aa
--- /dev/null
+++ b/.travis_scripts/run-clang-format.py
@@ -0,0 +1,356 @@
+#!/usr/bin/env python
+"""A wrapper script around clang-format, suitable for linting multiple files
+and to use for continuous integration.
+This is an alternative API for the clang-format command line.
+It runs over multiple files and directories in parallel.
+A diff output is produced and a sensible exit code is returned.
+
+NOTE: pulled from https://github.com/Sarcasm/run-clang-format, which is
+licensed under the MIT license.
+"""
+
+from __future__ import print_function, unicode_literals
+
+import argparse
+import codecs
+import difflib
+import fnmatch
+import io
+import multiprocessing
+import os
+import signal
+import subprocess
+import sys
+import traceback
+
+from functools import partial
+
+try:
+    from subprocess import DEVNULL  # py3k
+except ImportError:
+    DEVNULL = open(os.devnull, "wb")
+
+
+DEFAULT_EXTENSIONS = 'c,h,C,H,cpp,hpp,cc,hh,c++,h++,cxx,hxx'
+
+
+class ExitStatus:
+    SUCCESS = 0
+    DIFF = 1
+    TROUBLE = 2
+
+
+def list_files(files, recursive=False, extensions=None, exclude=None):
+    if extensions is None:
+        extensions = []
+    if exclude is None:
+        exclude = []
+
+    out = []
+    for file in files:
+        if recursive and os.path.isdir(file):
+            for dirpath, dnames, fnames in os.walk(file):
+                fpaths = [os.path.join(dirpath, fname) for fname in fnames]
+                for pattern in exclude:
+                    # os.walk() supports trimming down the dnames list
+                    # by modifying it in-place,
+                    # to avoid unnecessary directory listings.
+                    dnames[:] = [
+                        x for x in dnames
+                        if
+                        not fnmatch.fnmatch(os.path.join(dirpath, x), pattern)
+                    ]
+                    fpaths = [
+                        x for x in fpaths if not fnmatch.fnmatch(x, pattern)
+                    ]
+                for f in fpaths:
+                    ext = os.path.splitext(f)[1][1:]
+                    if ext in extensions:
+                        out.append(f)
+        else:
+            out.append(file)
+    return out
+
+
+def make_diff(file, original, reformatted):
+    return list(
+        difflib.unified_diff(
+            original,
+            reformatted,
+            fromfile='{}\t(original)'.format(file),
+            tofile='{}\t(reformatted)'.format(file),
+            n=3))
+
+
+class DiffError(Exception):
+    def __init__(self, message, errs=None):
+        super(DiffError, self).__init__(message)
+        self.errs = errs or []
+
+
+class UnexpectedError(Exception):
+    def __init__(self, message, exc=None):
+        super(UnexpectedError, self).__init__(message)
+        self.formatted_traceback = traceback.format_exc()
+        self.exc = exc
+
+
+def run_clang_format_diff_wrapper(args, file):
+    try:
+        ret = run_clang_format_diff(args, file)
+        return ret
+    except DiffError:
+        raise
+    except Exception as e:
+        raise UnexpectedError('{}: {}: {}'.format(file, e.__class__.__name__,
+                                                  e), e)
+
+
+def run_clang_format_diff(args, file):
+    try:
+        with io.open(file, 'r', encoding='utf-8') as f:
+            original = f.readlines()
+    except IOError as exc:
+        raise DiffError(str(exc))
+    invocation = [args.clang_format_executable, file]
+
+    # Use of utf-8 to decode the process output.
+    #
+    # Hopefully, this is the correct thing to do.
+    #
+    # It's done due to the following assumptions (which may be incorrect):
+    # - clang-format will returns the bytes read from the files as-is,
+    #   without conversion, and it is already assumed that the files use utf-8.
+    # - if the diagnostics were internationalized, they would use utf-8:
+    #   > Adding Translations to Clang
+    #   >
+    #   > Not possible yet!
+    #   > Diagnostic strings should be written in UTF-8,
+    #   > the client can translate to the relevant code page if needed.
+    #   > Each translation completely replaces the format string
+    #   > for the diagnostic.
+    #   > -- http://clang.llvm.org/docs/InternalsManual.html#internals-diag-translation
+    #
+    # It's not pretty, due to Python 2 & 3 compatibility.
+    encoding_py3 = {}
+    if sys.version_info[0] >= 3:
+        encoding_py3['encoding'] = 'utf-8'
+
+    try:
+        proc = subprocess.Popen(
+            invocation,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            universal_newlines=True,
+            **encoding_py3)
+    except OSError as exc:
+        raise DiffError(
+            "Command '{}' failed to start: {}".format(
+                subprocess.list2cmdline(invocation), exc
+            )
+        )
+    proc_stdout = proc.stdout
+    proc_stderr = proc.stderr
+    if sys.version_info[0] < 3:
+        # make the pipes compatible with Python 3,
+        # reading lines should output unicode
+        encoding = 'utf-8'
+        proc_stdout = codecs.getreader(encoding)(proc_stdout)
+        proc_stderr = codecs.getreader(encoding)(proc_stderr)
+    # hopefully the stderr pipe won't get full and block the process
+    outs = list(proc_stdout.readlines())
+    errs = list(proc_stderr.readlines())
+    proc.wait()
+    if proc.returncode:
+        raise DiffError(
+            "Command '{}' returned non-zero exit status {}".format(
+                subprocess.list2cmdline(invocation), proc.returncode
+            ),
+            errs,
+        )
+    return make_diff(file, original, outs), errs
+
+
+def bold_red(s):
+    return '\x1b[1m\x1b[31m' + s + '\x1b[0m'
+
+
+def colorize(diff_lines):
+    def bold(s):
+        return '\x1b[1m' + s + '\x1b[0m'
+
+    def cyan(s):
+        return '\x1b[36m' + s + '\x1b[0m'
+
+    def green(s):
+        return '\x1b[32m' + s + '\x1b[0m'
+
+    def red(s):
+        return '\x1b[31m' + s + '\x1b[0m'
+
+    for line in diff_lines:
+        if line[:4] in ['--- ', '+++ ']:
+            yield bold(line)
+        elif line.startswith('@@ '):
+            yield cyan(line)
+        elif line.startswith('+'):
+            yield green(line)
+        elif line.startswith('-'):
+            yield red(line)
+        else:
+            yield line
+
+
+def print_diff(diff_lines, use_color):
+    if use_color:
+        diff_lines = colorize(diff_lines)
+    if sys.version_info[0] < 3:
+        sys.stdout.writelines((l.encode('utf-8') for l in diff_lines))
+    else:
+        sys.stdout.writelines(diff_lines)
+
+
+def print_trouble(prog, message, use_colors):
+    error_text = 'error:'
+    if use_colors:
+        error_text = bold_red(error_text)
+    print("{}: {} {}".format(prog, error_text, message), file=sys.stderr)
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        '--clang-format-executable',
+        metavar='EXECUTABLE',
+        help='path to the clang-format executable',
+        default='clang-format')
+    parser.add_argument(
+        '--extensions',
+        help='comma separated list of file extensions (default: {})'.format(
+            DEFAULT_EXTENSIONS),
+        default=DEFAULT_EXTENSIONS)
+    parser.add_argument(
+        '-r',
+        '--recursive',
+        action='store_true',
+        help='run recursively over directories')
+    parser.add_argument('files', metavar='file', nargs='+')
+    parser.add_argument(
+        '-q',
+        '--quiet',
+        action='store_true')
+    parser.add_argument(
+        '-j',
+        metavar='N',
+        type=int,
+        default=0,
+        help='run N clang-format jobs in parallel'
+        ' (default number of cpus + 1)')
+    parser.add_argument(
+        '--color',
+        default='auto',
+        choices=['auto', 'always', 'never'],
+        help='show colored diff (default: auto)')
+    parser.add_argument(
+        '-e',
+        '--exclude',
+        metavar='PATTERN',
+        action='append',
+        default=[],
+        help='exclude paths matching the given glob-like pattern(s)'
+        ' from recursive search')
+
+    args = parser.parse_args()
+
+    # use default signal handling, like diff return SIGINT value on ^C
+    # https://bugs.python.org/issue14229#msg156446
+    signal.signal(signal.SIGINT, signal.SIG_DFL)
+    try:
+        signal.SIGPIPE
+    except AttributeError:
+        # compatibility, SIGPIPE does not exist on Windows
+        pass
+    else:
+        signal.signal(signal.SIGPIPE, signal.SIG_DFL)
+
+    colored_stdout = False
+    colored_stderr = False
+    if args.color == 'always':
+        colored_stdout = True
+        colored_stderr = True
+    elif args.color == 'auto':
+        colored_stdout = sys.stdout.isatty()
+        colored_stderr = sys.stderr.isatty()
+
+    version_invocation = [args.clang_format_executable, str("--version")]
+    try:
+        subprocess.check_call(version_invocation, stdout=DEVNULL)
+    except subprocess.CalledProcessError as e:
+        print_trouble(parser.prog, str(e), use_colors=colored_stderr)
+        return ExitStatus.TROUBLE
+    except OSError as e:
+        print_trouble(
+            parser.prog,
+            "Command '{}' failed to start: {}".format(
+                subprocess.list2cmdline(version_invocation), e
+            ),
+            use_colors=colored_stderr,
+        )
+        return ExitStatus.TROUBLE
+
+    retcode = ExitStatus.SUCCESS
+    files = list_files(
+        args.files,
+        recursive=args.recursive,
+        exclude=args.exclude,
+        extensions=args.extensions.split(','))
+
+    if not files:
+        return
+
+    njobs = args.j
+    if njobs == 0:
+        njobs = multiprocessing.cpu_count() + 1
+    njobs = min(len(files), njobs)
+
+    if njobs == 1:
+        # execute directly instead of in a pool,
+        # less overhead, simpler stacktraces
+        it = (run_clang_format_diff_wrapper(args, file) for file in files)
+        pool = None
+    else:
+        pool = multiprocessing.Pool(njobs)
+        it = pool.imap_unordered(
+            partial(run_clang_format_diff_wrapper, args), files)
+    while True:
+        try:
+            outs, errs = next(it)
+        except StopIteration:
+            break
+        except DiffError as e:
+            print_trouble(parser.prog, str(e), use_colors=colored_stderr)
+            retcode = ExitStatus.TROUBLE
+            sys.stderr.writelines(e.errs)
+        except UnexpectedError as e:
+            print_trouble(parser.prog, str(e), use_colors=colored_stderr)
+            sys.stderr.write(e.formatted_traceback)
+            retcode = ExitStatus.TROUBLE
+            # stop at the first unexpected error,
+            # something could be very wrong,
+            # don't process all files unnecessarily
+            if pool:
+                pool.terminate()
+            break
+        else:
+            sys.stderr.writelines(errs)
+            if outs == []:
+                continue
+            if not args.quiet:
+                print_diff(outs, use_color=colored_stdout)
+            if retcode == ExitStatus.SUCCESS:
+                retcode = ExitStatus.DIFF
+    return retcode
+
+
+if __name__ == '__main__':
+    sys.exit(main())
\ No newline at end of file
diff --git a/.travis_scripts/run-clang-format.sh b/.travis_scripts/run-clang-format.sh
new file mode 100755
index 0000000..9197284
--- /dev/null
+++ b/.travis_scripts/run-clang-format.sh
@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+python $DIR/run-clang-format.py -r $DIR/../src/**/ $DIR/../include/**/
\ No newline at end of file
diff --git a/include/json/config.h b/include/json/config.h
index 0ff5968..cbb5950 100644
--- a/include/json/config.h
+++ b/include/json/config.h
@@ -74,8 +74,8 @@
 #if defined(_MSC_VER) && _MSC_VER < 1900
 // As recommended at
 // https://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010
-extern JSON_API int
-msvc_pre1900_c99_snprintf(char* outBuf, size_t size, const char* format, ...);
+extern JSON_API int msvc_pre1900_c99_snprintf(char* outBuf, size_t size,
+                                              const char* format, ...);
 #define jsoncpp_snprintf msvc_pre1900_c99_snprintf
 #else
 #define jsoncpp_snprintf std::snprintf
@@ -104,9 +104,26 @@
 #define JSONCPP_OP_EXPLICIT
 #endif
 
-#if defined(__clang__)
-#define JSON_USE_INT64_DOUBLE_CONVERSION 1
-#elif defined(__GNUC__) && (__GNUC__ >= 6)
+#ifdef __clang__
+#if __has_extension(attribute_deprecated_with_message)
+#define JSONCPP_DEPRECATED(message) __attribute__((deprecated(message)))
+#endif
+#elif defined(__GNUC__) // not clang (gcc comes later since clang emulates gcc)
+#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))
+#define JSONCPP_DEPRECATED(message) __attribute__((deprecated(message)))
+#elif (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+#define JSONCPP_DEPRECATED(message) __attribute__((__deprecated__))
+#endif                  // GNUC version
+#elif defined(_MSC_VER) // MSVC (after clang because clang on Windows emulates
+                        // MSVC)
+#define JSONCPP_DEPRECATED(message) __declspec(deprecated(message))
+#endif // __clang__ || __GNUC__ || _MSC_VER
+
+#if !defined(JSONCPP_DEPRECATED)
+#define JSONCPP_DEPRECATED(message)
+#endif // if !defined(JSONCPP_DEPRECATED)
+
+#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ >= 6))
 #define JSON_USE_INT64_DOUBLE_CONVERSION 1
 #endif
 
@@ -139,16 +156,16 @@
 #endif // if defined(JSON_NO_INT64)
 
 template <typename T>
-using Allocator = typename std::conditional<JSONCPP_USING_SECURE_MEMORY,
-                                            SecureAllocator<T>,
-                                            std::allocator<T>>::type;
+using Allocator =
+    typename std::conditional<JSONCPP_USING_SECURE_MEMORY, SecureAllocator<T>,
+                              std::allocator<T>>::type;
 using String = std::basic_string<char, std::char_traits<char>, Allocator<char>>;
-using IStringStream = std::basic_istringstream<String::value_type,
-                                               String::traits_type,
-                                               String::allocator_type>;
-using OStringStream = std::basic_ostringstream<String::value_type,
-                                               String::traits_type,
-                                               String::allocator_type>;
+using IStringStream =
+    std::basic_istringstream<String::value_type, String::traits_type,
+                             String::allocator_type>;
+using OStringStream =
+    std::basic_ostringstream<String::value_type, String::traits_type,
+                             String::allocator_type>;
 using IStream = std::istream;
 using OStream = std::ostream;
 } // namespace Json
diff --git a/include/json/reader.h b/include/json/reader.h
index fb2365a..359c1eb 100644
--- a/include/json/reader.h
+++ b/include/json/reader.h
@@ -25,10 +25,6 @@
 
 #pragma pack(push, 8)
 
-#if defined(_MSC_VER)
-#pragma warning(disable : 4996)
-#endif
-
 namespace Json {
 
 /** \brief Unserialize a <a HREF="http://www.json.org">JSON</a> document into a
@@ -36,8 +32,9 @@
  *
  * \deprecated Use CharReader and CharReaderBuilder.
  */
-class [[deprecated(
-    "deprecated Use CharReader and CharReaderBuilder.")]] JSON_API Reader {
+
+class JSONCPP_DEPRECATED(
+    "Use CharReader and CharReaderBuilder instead.") JSON_API Reader {
 public:
   typedef char Char;
   typedef const Char* Location;
@@ -55,10 +52,12 @@
 
   /** \brief Constructs a Reader allowing all features for parsing.
    */
+  JSONCPP_DEPRECATED("Use CharReader and CharReaderBuilder instead")
   Reader();
 
   /** \brief Constructs a Reader allowing the specified feature set for parsing.
    */
+  JSONCPP_DEPRECATED("Use CharReader and CharReaderBuilder instead")
   Reader(const Features& features);
 
   /** \brief Read a Value from a <a HREF="http://www.json.org">JSON</a>
@@ -99,7 +98,7 @@
 
   /// \brief Parse from input stream.
   /// \see Json::operator>>(std::istream&, Json::Value&).
-  bool parse(IStream & is, Value & root, bool collectComments = true);
+  bool parse(IStream& is, Value& root, bool collectComments = true);
 
   /** \brief Returns a user friendly string that list errors in the parsed
    * document.
@@ -109,8 +108,8 @@
    * occurred during parsing.
    * \deprecated Use getFormattedErrorMessages() instead (typo fix).
    */
-  [[deprecated("Use getFormattedErrorMessages() instead.")]] String
-  getFormatedErrorMessages() const;
+  JSONCPP_DEPRECATED("Use getFormattedErrorMessages() instead.")
+  String getFormatedErrorMessages() const;
 
   /** \brief Returns a user friendly string that list errors in the parsed
    * document.
@@ -190,7 +189,7 @@
 
   typedef std::deque<ErrorInfo> Errors;
 
-  bool readToken(Token & token);
+  bool readToken(Token& token);
   void skipSpaces();
   bool match(const Char* pattern, int patternLength);
   bool readComment();
@@ -199,17 +198,17 @@
   bool readString();
   void readNumber();
   bool readValue();
-  bool readObject(Token & token);
-  bool readArray(Token & token);
-  bool decodeNumber(Token & token);
-  bool decodeNumber(Token & token, Value & decoded);
-  bool decodeString(Token & token);
-  bool decodeString(Token & token, String & decoded);
-  bool decodeDouble(Token & token);
-  bool decodeDouble(Token & token, Value & decoded);
-  bool decodeUnicodeCodePoint(Token & token, Location & current, Location end,
+  bool readObject(Token& token);
+  bool readArray(Token& token);
+  bool decodeNumber(Token& token);
+  bool decodeNumber(Token& token, Value& decoded);
+  bool decodeString(Token& token);
+  bool decodeString(Token& token, String& decoded);
+  bool decodeDouble(Token& token);
+  bool decodeDouble(Token& token, Value& decoded);
+  bool decodeUnicodeCodePoint(Token& token, Location& current, Location end,
                               unsigned int& unicode);
-  bool decodeUnicodeEscapeSequence(Token & token, Location & current,
+  bool decodeUnicodeEscapeSequence(Token& token, Location& current,
                                    Location end, unsigned int& unicode);
   bool addError(const String& message, Token& token, Location extra = nullptr);
   bool recoverFromError(TokenType skipUntilToken);
@@ -218,11 +217,11 @@
   void skipUntilSpace();
   Value& currentValue();
   Char getNextChar();
-  void getLocationLineAndColumn(Location location, int& line, int& column)
-      const;
+  void getLocationLineAndColumn(Location location, int& line,
+                                int& column) const;
   String getLocationLineAndColumn(Location location) const;
   void addComment(Location begin, Location end, CommentPlacement placement);
-  void skipCommentTokens(Token & token);
+  void skipCommentTokens(Token& token);
 
   static bool containsNewLine(Location begin, Location end);
   static String normalizeEOL(Location begin, Location end);
@@ -262,9 +261,7 @@
    * \return \c true if the document was successfully parsed, \c false if an
    * error occurred.
    */
-  virtual bool parse(char const* beginDoc,
-                     char const* endDoc,
-                     Value* root,
+  virtual bool parse(char const* beginDoc, char const* endDoc, Value* root,
                      String* errs) = 0;
 
   class JSON_API Factory {
@@ -364,9 +361,7 @@
  * Someday we might have a real StreamReader, but for now this
  * is convenient.
  */
-bool JSON_API parseFromStream(CharReader::Factory const&,
-                              IStream&,
-                              Value* root,
+bool JSON_API parseFromStream(CharReader::Factory const&, IStream&, Value* root,
                               String* errs);
 
 /** \brief Read from 'sin' into 'root'.
diff --git a/include/json/value.h b/include/json/value.h
index aa7bc54..a0a5a11 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -493,8 +493,8 @@
   /// Return the member named key if it exist, defaultValue otherwise.
   /// \note deep copy
   /// \note key may contain embedded nulls.
-  Value
-  get(const char* begin, const char* end, const Value& defaultValue) const;
+  Value get(const char* begin, const char* end,
+            const Value& defaultValue) const;
   /// Return the member named key if it exist, defaultValue otherwise.
   /// \note deep copy
   /// \param key may contain embedded nulls.
@@ -567,8 +567,8 @@
   //# endif
 
   /// \deprecated Always pass len.
-  [[deprecated("Use setComment(String const&) instead.")]] void
-  setComment(const char* comment, CommentPlacement placement) {
+  JSONCPP_DEPRECATED("Use setComment(String const&) instead.")
+  void setComment(const char* comment, CommentPlacement placement) {
     setComment(String(comment, strlen(comment)), placement);
   }
   /// Comments must be //... or /* ... */
@@ -691,8 +691,7 @@
  */
 class JSON_API Path {
 public:
-  Path(const String& path,
-       const PathArgument& a1 = PathArgument(),
+  Path(const String& path, const PathArgument& a1 = PathArgument(),
        const PathArgument& a2 = PathArgument(),
        const PathArgument& a3 = PathArgument(),
        const PathArgument& a4 = PathArgument(),
@@ -709,10 +708,8 @@
   typedef std::vector<PathArgument> Args;
 
   void makePath(const String& path, const InArgs& in);
-  void addPathInArg(const String& path,
-                    const InArgs& in,
-                    InArgs::const_iterator& itInArg,
-                    PathArgument::Kind kind);
+  void addPathInArg(const String& path, const InArgs& in,
+                    InArgs::const_iterator& itInArg, PathArgument::Kind kind);
   static void invalidPath(const String& path, int location);
 
   Args args_;
@@ -753,7 +750,8 @@
   /// objectValue.
   /// \deprecated This cannot be used for UTF-8 strings, since there can be
   /// embedded nulls.
-  [[deprecated("Use `key = name();` instead.")]] char const* memberName() const;
+  JSONCPP_DEPRECATED("Use `key = name();` instead.")
+  char const* memberName() const;
   /// Return the member name of the referenced Value, or NULL if it is not an
   /// objectValue.
   /// \note Better version than memberName(). Allows embedded nulls.
diff --git a/include/json/writer.h b/include/json/writer.h
index 9799a3b..a72c06a 100644
--- a/include/json/writer.h
+++ b/include/json/writer.h
@@ -145,7 +145,7 @@
 /** \brief Abstract class for writers.
  * \deprecated Use StreamWriter. (And really, this is an implementation detail.)
  */
-class [[deprecated("Use StreamWriter instead")]] JSON_API Writer {
+class JSONCPP_DEPRECATED("Use StreamWriter instead") JSON_API Writer {
 public:
   virtual ~Writer();
 
@@ -165,7 +165,7 @@
 #pragma warning(push)
 #pragma warning(disable : 4996) // Deriving from deprecated class
 #endif
-class [[deprecated("Use StreamWriterBuilder instead")]] JSON_API FastWriter
+class JSONCPP_DEPRECATED("Use StreamWriterBuilder instead") JSON_API FastWriter
     : public Writer {
 public:
   FastWriter();
@@ -225,8 +225,8 @@
 #pragma warning(push)
 #pragma warning(disable : 4996) // Deriving from deprecated class
 #endif
-class [[deprecated("Use StreamWriterBuilder instead")]] JSON_API StyledWriter
-    : public Writer {
+class JSONCPP_DEPRECATED("Use StreamWriterBuilder instead") JSON_API
+    StyledWriter : public Writer {
 public:
   StyledWriter();
   ~StyledWriter() override = default;
@@ -294,8 +294,8 @@
 #pragma warning(push)
 #pragma warning(disable : 4996) // Deriving from deprecated class
 #endif
-class [[deprecated(
-    "Use StreamWriterBuilder instead")]] JSON_API StyledStreamWriter {
+class JSONCPP_DEPRECATED("Use StreamWriterBuilder instead") JSON_API
+    StyledStreamWriter {
 public:
   /**
    * \param indentation Each level will be indented by this amount extra.
@@ -310,7 +310,7 @@
    * \note There is no point in deriving from Writer, since write() should not
    * return a value.
    */
-  void write(OStream & out, const Value& root);
+  void write(OStream& out, const Value& root);
 
 private:
   void writeValue(const Value& value);
@@ -346,10 +346,9 @@
 #endif // if defined(JSON_HAS_INT64)
 String JSON_API valueToString(LargestInt value);
 String JSON_API valueToString(LargestUInt value);
-String JSON_API
-valueToString(double value,
-              unsigned int precision = Value::defaultRealPrecision,
-              PrecisionType precisionType = PrecisionType::significantDigits);
+String JSON_API valueToString(
+    double value, unsigned int precision = Value::defaultRealPrecision,
+    PrecisionType precisionType = PrecisionType::significantDigits);
 String JSON_API valueToString(bool value);
 String JSON_API valueToQuotedString(const char* value);
 
diff --git a/src/jsontestrunner/main.cpp b/src/jsontestrunner/main.cpp
index d2d41aa..cb9db66 100644
--- a/src/jsontestrunner/main.cpp
+++ b/src/jsontestrunner/main.cpp
@@ -68,8 +68,8 @@
   return text;
 }
 
-static void
-printValueTree(FILE* fout, Json::Value& value, const Json::String& path = ".") {
+static void printValueTree(FILE* fout, Json::Value& value,
+                           const Json::String& path = ".") {
   if (value.hasComment(Json::commentBefore)) {
     fprintf(fout, "%s\n", value.getComment(Json::commentBefore).c_str());
   }
@@ -125,8 +125,7 @@
 static int parseAndSaveValueTree(const Json::String& input,
                                  const Json::String& actual,
                                  const Json::String& kind,
-                                 const Json::Features& features,
-                                 bool parseOnly,
+                                 const Json::Features& features, bool parseOnly,
                                  Json::Value* root) {
   Json::Reader reader(features);
   bool parsingSuccessful =
diff --git a/src/lib_json/json_reader.cpp b/src/lib_json/json_reader.cpp
index 5d6207c..ac673ff 100644
--- a/src/lib_json/json_reader.cpp
+++ b/src/lib_json/json_reader.cpp
@@ -89,8 +89,7 @@
 
 Reader::Reader(const Features& features) : features_(features) {}
 
-bool Reader::parse(const std::string& document,
-                   Value& root,
+bool Reader::parse(const std::string& document, Value& root,
                    bool collectComments) {
   document_.assign(document.begin(), document.end());
   const char* begin = document_.c_str();
@@ -111,9 +110,7 @@
   return parse(doc.data(), doc.data() + doc.size(), root, collectComments);
 }
 
-bool Reader::parse(const char* beginDoc,
-                   const char* endDoc,
-                   Value& root,
+bool Reader::parse(const char* beginDoc, const char* endDoc, Value& root,
                    bool collectComments) {
   if (!features_.allowComments_) {
     collectComments = false;
@@ -373,8 +370,7 @@
   return normalized;
 }
 
-void Reader::addComment(Location begin,
-                        Location end,
+void Reader::addComment(Location begin, Location end,
                         CommentPlacement placement) {
   assert(collectComments_);
   const String& normalized = normalizeEOL(begin, end);
@@ -677,10 +673,8 @@
   return true;
 }
 
-bool Reader::decodeUnicodeCodePoint(Token& token,
-                                    Location& current,
-                                    Location end,
-                                    unsigned int& unicode) {
+bool Reader::decodeUnicodeCodePoint(Token& token, Location& current,
+                                    Location end, unsigned int& unicode) {
 
   if (!decodeUnicodeEscapeSequence(token, current, end, unicode))
     return false;
@@ -704,8 +698,7 @@
   return true;
 }
 
-bool Reader::decodeUnicodeEscapeSequence(Token& token,
-                                         Location& current,
+bool Reader::decodeUnicodeEscapeSequence(Token& token, Location& current,
                                          Location end,
                                          unsigned int& ret_unicode) {
   if (end - current < 4)
@@ -753,8 +746,7 @@
   return false;
 }
 
-bool Reader::addErrorAndRecover(const String& message,
-                                Token& token,
+bool Reader::addErrorAndRecover(const String& message, Token& token,
                                 TokenType skipUntilToken) {
   addError(message, token);
   return recoverFromError(skipUntilToken);
@@ -768,8 +760,7 @@
   return *current_++;
 }
 
-void Reader::getLocationLineAndColumn(Location location,
-                                      int& line,
+void Reader::getLocationLineAndColumn(Location location, int& line,
                                       int& column) const {
   Location current = begin_;
   Location lastLineStart = current;
@@ -845,8 +836,7 @@
   return true;
 }
 
-bool Reader::pushError(const Value& value,
-                       const String& message,
+bool Reader::pushError(const Value& value, const String& message,
                        const Value& extra) {
   ptrdiff_t const length = end_ - begin_;
   if (value.getOffsetStart() > length || value.getOffsetLimit() > length ||
@@ -900,9 +890,7 @@
   };
 
   OurReader(OurFeatures const& features);
-  bool parse(const char* beginDoc,
-             const char* endDoc,
-             Value& root,
+  bool parse(const char* beginDoc, const char* endDoc, Value& root,
              bool collectComments = true);
   String getFormattedErrorMessages() const;
   std::vector<StructuredError> getStructuredErrors() const;
@@ -968,24 +956,19 @@
   bool decodeString(Token& token, String& decoded);
   bool decodeDouble(Token& token);
   bool decodeDouble(Token& token, Value& decoded);
-  bool decodeUnicodeCodePoint(Token& token,
-                              Location& current,
-                              Location end,
+  bool decodeUnicodeCodePoint(Token& token, Location& current, Location end,
                               unsigned int& unicode);
-  bool decodeUnicodeEscapeSequence(Token& token,
-                                   Location& current,
-                                   Location end,
-                                   unsigned int& unicode);
+  bool decodeUnicodeEscapeSequence(Token& token, Location& current,
+                                   Location end, unsigned int& unicode);
   bool addError(const String& message, Token& token, Location extra = nullptr);
   bool recoverFromError(TokenType skipUntilToken);
-  bool addErrorAndRecover(const String& message,
-                          Token& token,
+  bool addErrorAndRecover(const String& message, Token& token,
                           TokenType skipUntilToken);
   void skipUntilSpace();
   Value& currentValue();
   Char getNextChar();
-  void
-  getLocationLineAndColumn(Location location, int& line, int& column) const;
+  void getLocationLineAndColumn(Location location, int& line,
+                                int& column) const;
   String getLocationLineAndColumn(Location location) const;
   void addComment(Location begin, Location end, CommentPlacement placement);
   void skipCommentTokens(Token& token);
@@ -1022,9 +1005,7 @@
     : begin_(), end_(), current_(), lastValueEnd_(), lastValue_(),
       features_(features), collectComments_() {}
 
-bool OurReader::parse(const char* beginDoc,
-                      const char* endDoc,
-                      Value& root,
+bool OurReader::parse(const char* beginDoc, const char* endDoc, Value& root,
                       bool collectComments) {
   if (!features_.allowComments_) {
     collectComments = false;
@@ -1341,8 +1322,7 @@
   return normalized;
 }
 
-void OurReader::addComment(Location begin,
-                           Location end,
+void OurReader::addComment(Location begin, Location end,
                            CommentPlacement placement) {
   assert(collectComments_);
   const String& normalized = normalizeEOL(begin, end);
@@ -1700,10 +1680,8 @@
   return true;
 }
 
-bool OurReader::decodeUnicodeCodePoint(Token& token,
-                                       Location& current,
-                                       Location end,
-                                       unsigned int& unicode) {
+bool OurReader::decodeUnicodeCodePoint(Token& token, Location& current,
+                                       Location end, unsigned int& unicode) {
 
   if (!decodeUnicodeEscapeSequence(token, current, end, unicode))
     return false;
@@ -1727,8 +1705,7 @@
   return true;
 }
 
-bool OurReader::decodeUnicodeEscapeSequence(Token& token,
-                                            Location& current,
+bool OurReader::decodeUnicodeEscapeSequence(Token& token, Location& current,
                                             Location end,
                                             unsigned int& ret_unicode) {
   if (end - current < 4)
@@ -1776,8 +1753,7 @@
   return false;
 }
 
-bool OurReader::addErrorAndRecover(const String& message,
-                                   Token& token,
+bool OurReader::addErrorAndRecover(const String& message, Token& token,
                                    TokenType skipUntilToken) {
   addError(message, token);
   return recoverFromError(skipUntilToken);
@@ -1791,8 +1767,7 @@
   return *current_++;
 }
 
-void OurReader::getLocationLineAndColumn(Location location,
-                                         int& line,
+void OurReader::getLocationLineAndColumn(Location location, int& line,
                                          int& column) const {
   Location current = begin_;
   Location lastLineStart = current;
@@ -1863,8 +1838,7 @@
   return true;
 }
 
-bool OurReader::pushError(const Value& value,
-                          const String& message,
+bool OurReader::pushError(const Value& value, const String& message,
                           const Value& extra) {
   ptrdiff_t length = end_ - begin_;
   if (value.getOffsetStart() > length || value.getOffsetLimit() > length ||
@@ -1891,9 +1865,7 @@
 public:
   OurCharReader(bool collectComments, OurFeatures const& features)
       : collectComments_(collectComments), reader_(features) {}
-  bool parse(char const* beginDoc,
-             char const* endDoc,
-             Value* root,
+  bool parse(char const* beginDoc, char const* endDoc, Value* root,
              String* errs) override {
     bool ok = reader_.parse(beginDoc, endDoc, *root, collectComments_);
     if (errs) {
@@ -1989,9 +1961,7 @@
 //////////////////////////////////
 // global functions
 
-bool parseFromStream(CharReader::Factory const& fact,
-                     IStream& sin,
-                     Value* root,
+bool parseFromStream(CharReader::Factory const& fact, IStream& sin, Value* root,
                      String* errs) {
   OStringStream ssin;
   ssin << sin.rdbuf();
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 6ee999c..cf93ec7 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -22,10 +22,8 @@
 // Provide implementation equivalent of std::snprintf for older _MSC compilers
 #if defined(_MSC_VER) && _MSC_VER < 1900
 #include <stdarg.h>
-static int msvc_pre1900_c99_vsnprintf(char* outBuf,
-                                      size_t size,
-                                      const char* format,
-                                      va_list ap) {
+static int msvc_pre1900_c99_vsnprintf(char* outBuf, size_t size,
+                                      const char* format, va_list ap) {
   int count = -1;
   if (size != 0)
     count = _vsnprintf_s(outBuf, size, _TRUNCATE, format, ap);
@@ -34,10 +32,8 @@
   return count;
 }
 
-int JSON_API msvc_pre1900_c99_snprintf(char* outBuf,
-                                       size_t size,
-                                       const char* format,
-                                       ...) {
+int JSON_API msvc_pre1900_c99_snprintf(char* outBuf, size_t size,
+                                       const char* format, ...) {
   va_list ap;
   va_start(ap, format);
   const int count = msvc_pre1900_c99_vsnprintf(outBuf, size, format, ap);
@@ -156,10 +152,8 @@
       0; // to avoid buffer over-run accidents by users later
   return newString;
 }
-inline static void decodePrefixedString(bool isPrefixed,
-                                        char const* prefixed,
-                                        unsigned* length,
-                                        char const** value) {
+inline static void decodePrefixedString(bool isPrefixed, char const* prefixed,
+                                        unsigned* length, char const** value) {
   if (!isPrefixed) {
     *length = static_cast<unsigned>(strlen(prefixed));
     *value = prefixed;
@@ -235,8 +229,7 @@
 
 Value::CZString::CZString(ArrayIndex index) : cstr_(nullptr), index_(index) {}
 
-Value::CZString::CZString(char const* str,
-                          unsigned length,
+Value::CZString::CZString(char const* str, unsigned length,
                           DuplicationPolicy allocate)
     : cstr_(str) {
   // allocate != duplicate
@@ -1165,8 +1158,7 @@
   return this->value_.map_->emplace(size(), std::move(value)).first->second;
 }
 
-Value Value::get(char const* begin,
-                 char const* end,
+Value Value::get(char const* begin, char const* end,
                  Value const& defaultValue) const {
   Value const* found = find(begin, end);
   return !found ? defaultValue : *found;
@@ -1564,11 +1556,8 @@
 // class Path
 // //////////////////////////////////////////////////////////////////
 
-Path::Path(const String& path,
-           const PathArgument& a1,
-           const PathArgument& a2,
-           const PathArgument& a3,
-           const PathArgument& a4,
+Path::Path(const String& path, const PathArgument& a1, const PathArgument& a2,
+           const PathArgument& a3, const PathArgument& a4,
            const PathArgument& a5) {
   InArgs in;
   in.reserve(5);
@@ -1611,8 +1600,7 @@
   }
 }
 
-void Path::addPathInArg(const String& /*path*/,
-                        const InArgs& in,
+void Path::addPathInArg(const String& /*path*/, const InArgs& in,
                         InArgs::const_iterator& itInArg,
                         PathArgument::Kind kind) {
   if (itInArg == in.end()) {
diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index 4b91035..e16d84f 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -122,10 +122,8 @@
 #endif // # if defined(JSON_HAS_INT64)
 
 namespace {
-String valueToString(double value,
-                     bool useSpecialFloats,
-                     unsigned int precision,
-                     PrecisionType precisionType) {
+String valueToString(double value, bool useSpecialFloats,
+                     unsigned int precision, PrecisionType precisionType) {
   // Print into the buffer. We need not request the alternative representation
   // that always has a decimal point because JSON doesn't distinguish the
   // concepts of reals and integers.
@@ -168,8 +166,7 @@
 }
 } // namespace
 
-String valueToString(double value,
-                     unsigned int precision,
+String valueToString(double value, unsigned int precision,
                      PrecisionType precisionType) {
   return valueToString(value, false, precision, precisionType);
 }
@@ -864,14 +861,10 @@
 };
 
 struct BuiltStyledStreamWriter : public StreamWriter {
-  BuiltStyledStreamWriter(String indentation,
-                          CommentStyle::Enum cs,
-                          String colonSymbol,
-                          String nullSymbol,
-                          String endingLineFeedSymbol,
-                          bool useSpecialFloats,
-                          unsigned int precision,
-                          PrecisionType precisionType);
+  BuiltStyledStreamWriter(String indentation, CommentStyle::Enum cs,
+                          String colonSymbol, String nullSymbol,
+                          String endingLineFeedSymbol, bool useSpecialFloats,
+                          unsigned int precision, PrecisionType precisionType);
   int write(Value const& root, OStream* sout) override;
 
 private:
@@ -903,14 +896,10 @@
   unsigned int precision_;
   PrecisionType precisionType_;
 };
-BuiltStyledStreamWriter::BuiltStyledStreamWriter(String indentation,
-                                                 CommentStyle::Enum cs,
-                                                 String colonSymbol,
-                                                 String nullSymbol,
-                                                 String endingLineFeedSymbol,
-                                                 bool useSpecialFloats,
-                                                 unsigned int precision,
-                                                 PrecisionType precisionType)
+BuiltStyledStreamWriter::BuiltStyledStreamWriter(
+    String indentation, CommentStyle::Enum cs, String colonSymbol,
+    String nullSymbol, String endingLineFeedSymbol, bool useSpecialFloats,
+    unsigned int precision, PrecisionType precisionType)
     : rightMargin_(74), indentation_(std::move(indentation)), cs_(cs),
       colonSymbol_(std::move(colonSymbol)), nullSymbol_(std::move(nullSymbol)),
       endingLineFeedSymbol_(std::move(endingLineFeedSymbol)),
diff --git a/src/test_lib_json/jsontest.cpp b/src/test_lib_json/jsontest.cpp
index c0b5296..0cc500a 100644
--- a/src/test_lib_json/jsontest.cpp
+++ b/src/test_lib_json/jsontest.cpp
@@ -82,8 +82,8 @@
 
 void TestResult::setTestName(const Json::String& name) { name_ = name; }
 
-TestResult&
-TestResult::addFailure(const char* file, unsigned int line, const char* expr) {
+TestResult& TestResult::addFailure(const char* file, unsigned int line,
+                                   const char* expr) {
   /// Walks the PredicateContext stack adding them to failures_ if not already
   /// added.
   unsigned int nestingLevel = 0;
@@ -107,10 +107,8 @@
   return *this;
 }
 
-void TestResult::addFailureInfo(const char* file,
-                                unsigned int line,
-                                const char* expr,
-                                unsigned int nestingLevel) {
+void TestResult::addFailureInfo(const char* file, unsigned int line,
+                                const char* expr, unsigned int nestingLevel) {
   Failure failure;
   failure.file_ = file;
   failure.line_ = line;
@@ -342,8 +340,8 @@
 
 #if defined(_MSC_VER) && defined(_DEBUG)
 // Hook MSVCRT assertions to prevent dialog from appearing
-static int
-msvcrtSilentReportHook(int reportType, char* message, int* /*returnValue*/) {
+static int msvcrtSilentReportHook(int reportType, char* message,
+                                  int* /*returnValue*/) {
   // The default CRT handling of error and assertion is to display
   // an error dialog to the user.
   // Instead, when an error or an assertion occurs, we force the
@@ -418,12 +416,9 @@
 }
 #endif
 
-TestResult& checkStringEqual(TestResult& result,
-                             const Json::String& expected,
-                             const Json::String& actual,
-                             const char* file,
-                             unsigned int line,
-                             const char* expr) {
+TestResult& checkStringEqual(TestResult& result, const Json::String& expected,
+                             const Json::String& actual, const char* file,
+                             unsigned int line, const char* expr) {
   if (expected != actual) {
     result.addFailure(file, line, expr);
     result << "Expected: '" << expected << "'\n";
diff --git a/src/test_lib_json/jsontest.h b/src/test_lib_json/jsontest.h
index e9c11a4..5d213dc 100644
--- a/src/test_lib_json/jsontest.h
+++ b/src/test_lib_json/jsontest.h
@@ -68,8 +68,8 @@
   void setTestName(const Json::String& name);
 
   /// Adds an assertion failure.
-  TestResult&
-  addFailure(const char* file, unsigned int line, const char* expr = nullptr);
+  TestResult& addFailure(const char* file, unsigned int line,
+                         const char* expr = nullptr);
 
   /// Removes the last PredicateContext added to the predicate stack
   /// chained list.
@@ -98,9 +98,7 @@
 private:
   TestResult& addToLastFailure(const Json::String& message);
   /// Adds a failure or a predicate context
-  void addFailureInfo(const char* file,
-                      unsigned int line,
-                      const char* expr,
+  void addFailureInfo(const char* file, unsigned int line, const char* expr,
                       unsigned int nestingLevel);
   static Json::String indentText(const Json::String& text,
                                  const Json::String& indent);
@@ -176,12 +174,8 @@
 };
 
 template <typename T, typename U>
-TestResult& checkEqual(TestResult& result,
-                       T expected,
-                       U actual,
-                       const char* file,
-                       unsigned int line,
-                       const char* expr) {
+TestResult& checkEqual(TestResult& result, T expected, U actual,
+                       const char* file, unsigned int line, const char* expr) {
   if (static_cast<U>(expected) != actual) {
     result.addFailure(file, line, expr);
     result << "Expected: " << static_cast<U>(expected) << "\n";
@@ -196,12 +190,9 @@
 Json::String ToJsonString(std::string in);
 #endif
 
-TestResult& checkStringEqual(TestResult& result,
-                             const Json::String& expected,
-                             const Json::String& actual,
-                             const char* file,
-                             unsigned int line,
-                             const char* expr);
+TestResult& checkStringEqual(TestResult& result, const Json::String& expected,
+                             const Json::String& actual, const char* file,
+                             unsigned int line, const char* expr);
 
 } // namespace JsonTest