diff --git a/contributors.txt b/contributors.txt
index a19451c6c..c784d5fdf 100644
--- a/contributors.txt
+++ b/contributors.txt
@@ -251,4 +251,7 @@ YYYY/MM/DD, github id, Full name, email
 2020/05/25, graknol, Sindre van der Linden, graknol@gmail.com
 2020/05/31, d-markey, David Markey, dmarkey@free.fr
 2020/06/02, cohomology, Kilian Kilger, kkilger AT gmail.com
-2020/07/01, sha-N, Shan M Mathews, admin@bluestarqatar.com
\ No newline at end of file
+2020/06/04, IohannRabeson, Iohann Rabeson, iotaka6@gmail.com
+2020/07/01, sha-N, Shan M Mathews, admin@bluestarqatar.com
+2020/08/22, stevenjohnstone, Steven Johnstone, steven.james.johnstone@gmail.com
+2020/09/06, ArthurSonzogni, Sonzogni Arthur, arthursonzogni@gmail.com
\ No newline at end of file
diff --git a/doc/cpp-target.md b/doc/cpp-target.md
index eec7cf88b..1fc8e8684 100644
--- a/doc/cpp-target.md
+++ b/doc/cpp-target.md
@@ -65,7 +65,7 @@ int main(int argc, const char* argv[]) {
 
   tree::ParseTree *tree = parser.key();
   TreeShapeListener listener;
-  tree::ParseTreeWalker::DEFAULT->walk(&listener, tree);
+  tree::ParseTreeWalker::DEFAULT.walk(&listener, tree);
 
   return 0;
 }
diff --git a/runtime/Cpp/CMakeLists.txt b/runtime/Cpp/CMakeLists.txt
index 9610d7b9b..e763f85d4 100644
--- a/runtime/Cpp/CMakeLists.txt
+++ b/runtime/Cpp/CMakeLists.txt
@@ -19,7 +19,7 @@ if(NOT WITH_DEMO)
     FORCE)
 endif(NOT WITH_DEMO)
 
-option(WITH_LIBCXX "Building with clang++ and libc++(in Linux). To enable with: -DWITH_LIBCXX=On" On)
+option(WITH_LIBCXX "Building with clang++ and libc++(in Linux). To enable with: -DWITH_LIBCXX=On" Off)
 option(WITH_STATIC_CRT "(Visual C++) Enable to statically link CRT, which avoids requiring users to install the redistribution package.
  To disable with: -DWITH_STATIC_CRT=Off" On)
 
diff --git a/runtime/Cpp/runtime/antlr4cpp-vs2019.vcxproj b/runtime/Cpp/runtime/antlr4cpp-vs2019.vcxproj
index 42a81fc06..54f0aeb14 100644
--- a/runtime/Cpp/runtime/antlr4cpp-vs2019.vcxproj
+++ b/runtime/Cpp/runtime/antlr4cpp-vs2019.vcxproj
@@ -182,6 +182,7 @@
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
       <MinimalRebuild>false</MinimalRebuild>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -201,6 +202,7 @@
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
       <MinimalRebuild>false</MinimalRebuild>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -220,6 +222,7 @@
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
       <MinimalRebuild>false</MinimalRebuild>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -239,6 +242,7 @@
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
       <MinimalRebuild>false</MinimalRebuild>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -259,6 +263,7 @@
       </ForcedIncludeFiles>
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -281,6 +286,7 @@
       </ForcedIncludeFiles>
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -303,6 +309,7 @@
       </ForcedIncludeFiles>
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
@@ -325,6 +332,7 @@
       </ForcedIncludeFiles>
       <DisableSpecificWarnings>4251</DisableSpecificWarnings>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>
+      <AdditionalOptions>/Zc:__cplusplus %(AdditionalOptions)</AdditionalOptions>
     </ClCompile>
     <Link>
       <SubSystem>Windows</SubSystem>
diff --git a/runtime/Cpp/runtime/src/ANTLRInputStream.cpp b/runtime/Cpp/runtime/src/ANTLRInputStream.cpp
index a5e21618e..2e06c5efc 100755
--- a/runtime/Cpp/runtime/src/ANTLRInputStream.cpp
+++ b/runtime/Cpp/runtime/src/ANTLRInputStream.cpp
@@ -17,7 +17,11 @@ using namespace antlrcpp;
 
 using misc::Interval;
 
+#if __cplusplus >= 201703L
+ANTLRInputStream::ANTLRInputStream(std::string_view input) {
+#else
 ANTLRInputStream::ANTLRInputStream(const std::string &input) {
+#endif
   InitializeInstanceFields();
   load(input);
 }
@@ -31,6 +35,16 @@ ANTLRInputStream::ANTLRInputStream(std::istream &stream) {
   load(stream);
 }
 
+#if __cplusplus >= 201703L
+void ANTLRInputStream::load(std::string_view input) {
+  // Remove the UTF-8 BOM if present.
+  constexpr std::string_view bom = "\xef\xbb\xbf";
+  if (input.compare(0, 3, bom) == 0)
+    input.remove_prefix(3);
+  _data = antlrcpp::utf8_to_utf32(input.data(), input.data() + input.size());
+  p = 0;
+}
+#else
 void ANTLRInputStream::load(const std::string &input) {
   // Remove the UTF-8 BOM if present.
   const char bom[4] = "\xef\xbb\xbf";
@@ -40,6 +54,7 @@ void ANTLRInputStream::load(const std::string &input) {
     _data = antlrcpp::utf8_to_utf32(input.data(), input.data() + input.size());
   p = 0;
 }
+#endif
 
 void ANTLRInputStream::load(std::istream &stream) {
   if (!stream.good() || stream.eof()) // No fail, bad or EOF.
diff --git a/runtime/Cpp/runtime/src/ANTLRInputStream.h b/runtime/Cpp/runtime/src/ANTLRInputStream.h
index e9850504d..7b575df2e 100755
--- a/runtime/Cpp/runtime/src/ANTLRInputStream.h
+++ b/runtime/Cpp/runtime/src/ANTLRInputStream.h
@@ -25,11 +25,19 @@ namespace antlr4 {
     /// What is name or source of this char stream?
     std::string name;
 
+#if __cplusplus >= 201703L
+    ANTLRInputStream(std::string_view input = "");
+#else
     ANTLRInputStream(const std::string &input = "");
+#endif
     ANTLRInputStream(const char data_[], size_t numberOfActualCharsInArray);
     ANTLRInputStream(std::istream &stream);
 
+#if __cplusplus >= 201703L
+    virtual void load(std::string_view input);
+#else
     virtual void load(const std::string &input);
+#endif
     virtual void load(std::istream &stream);
 
     /// Reset the stream so that it's in the same state it was
diff --git a/runtime/Cpp/runtime/src/Vocabulary.cpp b/runtime/Cpp/runtime/src/Vocabulary.cpp
index dcfa45e4b..9bbf0b23a 100755
--- a/runtime/Cpp/runtime/src/Vocabulary.cpp
+++ b/runtime/Cpp/runtime/src/Vocabulary.cpp
@@ -22,8 +22,7 @@ Vocabulary::Vocabulary(const std::vector<std::string> &literalNames,
   // See note here on -1 part: https://github.com/antlr/antlr4/pull/1146
 }
 
-Vocabulary::~Vocabulary() {
-}
+Vocabulary::~Vocabulary() = default;
 
 Vocabulary Vocabulary::fromTokenNames(const std::vector<std::string> &tokenNames) {
   if (tokenNames.empty()) {
@@ -34,25 +33,18 @@ Vocabulary Vocabulary::fromTokenNames(const std::vector<std::string> &tokenNames
   std::vector<std::string> symbolicNames = tokenNames;
   std::locale locale;
   for (size_t i = 0; i < tokenNames.size(); i++) {
-    std::string tokenName = tokenNames[i];
-    if (tokenName == "") {
+    const std::string& tokenName = tokenNames[i];
+    if (tokenName.empty()) {
       continue;
+    } else if (tokenName.front() == '\'') {
+      symbolicNames[i].clear();
+    } else if (std::isupper(tokenName.front(), locale)) {
+      literalNames[i].clear();
+    } else {
+      // wasn't a literal or symbolic name
+      literalNames[i].clear();
+      symbolicNames[i].clear();
     }
-
-    if (!tokenName.empty()) {
-      char firstChar = tokenName[0];
-      if (firstChar == '\'') {
-        symbolicNames[i] = "";
-        continue;
-      } else if (std::isupper(firstChar, locale)) {
-        literalNames[i] = "";
-        continue;
-      }
-    }
-
-    // wasn't a literal or symbolic name
-    literalNames[i] = "";
-    symbolicNames[i] = "";
   }
 
   return Vocabulary(literalNames, symbolicNames, tokenNames);
diff --git a/runtime/Cpp/runtime/src/Vocabulary.h b/runtime/Cpp/runtime/src/Vocabulary.h
index 7dbf85cd3..f06ce6978 100755
--- a/runtime/Cpp/runtime/src/Vocabulary.h
+++ b/runtime/Cpp/runtime/src/Vocabulary.h
@@ -14,9 +14,6 @@ namespace dfa {
   /// interface.
   class ANTLR4CPP_PUBLIC Vocabulary {
   public:
-    Vocabulary(Vocabulary const&) = default;
-    virtual ~Vocabulary();
-
     /// Gets an empty <seealso cref="Vocabulary"/> instance.
     ///
     /// <para>
@@ -25,7 +22,9 @@ namespace dfa {
     /// except <seealso cref="Token#EOF"/>.</para>
     static const Vocabulary EMPTY_VOCABULARY;
 
-    Vocabulary() {}
+    Vocabulary() = default;
+    Vocabulary(Vocabulary const&) = default;
+    virtual ~Vocabulary();
 
     /// <summary>
     /// Constructs a new instance of <seealso cref="Vocabulary"/> from the specified
diff --git a/tool/resources/org/antlr/v4/tool/templates/codegen/Cpp/Cpp.stg b/tool/resources/org/antlr/v4/tool/templates/codegen/Cpp/Cpp.stg
index 6930e3e47..2b8ed0b13 100644
--- a/tool/resources/org/antlr/v4/tool/templates/codegen/Cpp/Cpp.stg
+++ b/tool/resources/org/antlr/v4/tool/templates/codegen/Cpp/Cpp.stg
@@ -63,7 +63,7 @@ public:
   };
 <endif>
 
-  <lexer.name>(antlr4::CharStream *input);
+  explicit <lexer.name>(antlr4::CharStream *input);
   ~<lexer.name>();
 
   <namedActions.members>
@@ -192,23 +192,23 @@ atn::ATN <lexer.name>::_atn;
 std::vector\<uint16_t> <lexer.name>::_serializedATN;
 
 std::vector\<std::string> <lexer.name>::_ruleNames = {
-  <lexer.ruleNames: {r | u8"<r>"}; separator = ", ", wrap, anchor>
+  <lexer.ruleNames: {r | "<r>"}; separator = ", ", wrap, anchor>
 };
 
 std::vector\<std::string> <lexer.name>::_channelNames = {
-  "DEFAULT_TOKEN_CHANNEL", "HIDDEN"<if (lexer.channels)>, <lexer.channels: {c | u8"<c>"}; separator = ", ", wrap, anchor><endif>
+  "DEFAULT_TOKEN_CHANNEL", "HIDDEN"<if (lexer.channels)>, <lexer.channels: {c | "<c>"}; separator = ", ", wrap, anchor><endif>
 };
 
 std::vector\<std::string> <lexer.name>::_modeNames = {
-  <lexer.modes: {m | u8"<m>"}; separator = ", ", wrap, anchor>
+  <lexer.modes: {m | "<m>"}; separator = ", ", wrap, anchor>
 };
 
 std::vector\<std::string> <lexer.name>::_literalNames = {
-  <lexer.literalNames: {t | u8<t>}; null = "\"\"", separator = ", ", wrap, anchor>
+  <lexer.literalNames: {t | <t>}; null = "\"\"", separator = ", ", wrap, anchor>
 };
 
 std::vector\<std::string> <lexer.name>::_symbolicNames = {
-  <lexer.symbolicNames: {t | u8<t>}; null = "\"\"", separator = ", ", wrap, anchor>
+  <lexer.symbolicNames: {t | <t>}; null = "\"\"", separator = ", ", wrap, anchor>
 };
 
 dfa::Vocabulary <lexer.name>::_vocabulary(_literalNames, _symbolicNames);
@@ -290,7 +290,7 @@ public:
   };
 <endif>
 
-  <parser.name>(antlr4::TokenStream *input);
+  explicit <parser.name>(antlr4::TokenStream *input);
   ~<parser.name>();
 
   virtual std::string getGrammarFileName() const override;
@@ -710,6 +710,8 @@ switch (getInterpreter\<atn::ParserATNSimulator>()->adaptivePredict(_input, <cho
   break;
 \}
 }; separator="\n">
+default:
+  break;
 }
 >>
 
@@ -724,6 +726,8 @@ switch (getInterpreter\<atn::ParserATNSimulator>()->adaptivePredict(_input, <cho
   break;
 \}
 }; separator = "\n">
+default:
+  break;
 }
 >>