add C++23 support

lib/Interpreter/CIFactory.cpp

@@ -61,14 +61,18 @@ using namespace cling;
 
 namespace {
   static constexpr unsigned CxxStdCompiledWith() {
+    // The value of __cplusplus in GCC < 14 is 202100L when -std=c++2b or
+    // -std=c++23 is specified, thus we relax the check to 202100L.
+#if __cplusplus >= 202100L
+    return 23;
+#elif __cplusplus >  201703L
+    return 20;
+#elif __cplusplus > 201402L
+    return 17;
     // The value of __cplusplus in GCC < 5.0 (e.g. 4.9.3) when
     // either -std=c++1y or -std=c++14 is specified is 201300L, which fails
     // the test for C++14 or more (201402L) as previously specified.
     // I would claim that the check should be relaxed to:
-#if __cplusplus >  201703L
-    return 20;
-#elif __cplusplus > 201402L
-    return 17;
 #elif __cplusplus > 201103L || (defined(_WIN32) && _MSC_VER >= 1900)
     return 14;
 #elif __cplusplus >= 201103L
@@ -941,6 +945,8 @@ namespace {
     // Sanity check that clang delivered the language standard requested
     if (CompilerOpts.DefaultLanguage(&LangOpts)) {
       switch (CxxStdCompiledWith()) {
+        case 23: assert(LangOpts.CPlusPlus23 && "Language version mismatch");
+          LLVM_FALLTHROUGH;
         case 20: assert(LangOpts.CPlusPlus20 && "Language version mismatch");
           LLVM_FALLTHROUGH;
         case 17: assert(LangOpts.CPlusPlus17 && "Language version mismatch");
@@ -1343,6 +1349,7 @@ namespace {
       // and by enforcing the std version now cling is telling clang what to
       // do, rather than after clang has dedcuded a default.
       switch (CxxStdCompiledWith()) {
+        case 23: argvCompile.emplace_back("-std=c++23"); break;
         case 20: argvCompile.emplace_back("-std=c++20"); break;
         case 17: argvCompile.emplace_back("-std=c++17"); break;
         case 14: argvCompile.emplace_back("-std=c++14"); break;

lib/Interpreter/IncrementalCUDADeviceCompiler.cpp

@@ -117,6 +117,8 @@ namespace cling {
       cppStdVersion = "-std=c++1z";
     if (langOpts.CPlusPlus20)
       cppStdVersion = "-std=c++20";
+    if (langOpts.CPlusPlus23)
+      cppStdVersion = "-std=c++23";
 
     if (cppStdVersion.empty())
       llvm::errs()

tools/Jupyter/kernel/clingkernel.py

@@ -90,8 +90,8 @@ def _banner_default(self):
     flush_interval = Float(0.25, config=True)
 
     std = CaselessStrEnum(default_value='c++11',
-            values = ['c++11', 'c++14', 'c++1z', 'c++17', 'c++20', 'c++2b'],
-            help="C++ standard to use, either c++2b, c++20, c++17, c++1z, c++14 or c++11").tag(config=True);
+            values = ['c++11', 'c++14', 'c++1z', 'c++17', 'c++20', 'c++2b', 'c++23' ],
+            help="C++ standard to use, either c++23, c++2b, c++20, c++17, c++1z, c++14 or c++11").tag(config=True);
 
     def __init__(self, **kwargs):
         super(ClingKernel, self).__init__(**kwargs)