Add DemangleSymbol function

Author: Vipul-Cariappa

include/clang/Interpreter/CppInterOp.h

@@ -185,6 +185,9 @@ namespace Cpp {
   ///\returns the version string information of the library.
   CPPINTEROP_API std::string GetVersion();
 
+  ///\returns the demangled representation of the given mangled_name
+  CPPINTEROP_API std::string Demangle(const std::string& mangled_name);
+
   /// Enables or disables the debugging printouts on stderr.
   /// Debugging output can be enabled also by the environment variable
   /// CPPINTEROP_EXTRA_INTERPRETER_ARGS. For example,

lib/Interpreter/CppInterOp.cpp

@@ -31,6 +31,7 @@
 
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Demangle/Demangle.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_os_ostream.h"
@@ -155,6 +156,25 @@ namespace Cpp {
     return fullVersion + "[" + clang::getClangFullVersion() + "])\n";
   }
 
+  std::string Demangle(const std::string& mangled_name) {
+#if CLANG_VERSION_MAJOR > 16
+#if defined(MSVC)
+    std::string demangle = microsoftDemangle(mangled_name, nullptr, nullptr);
+#else
+    std::string demangle = itaniumDemangle(mangled_name);
+#endif
+#else
+#ifdef MSVC
+    std::string demangle = microsoftDemangle(mangled_name.c_str(), nullptr,
+                                             nullptr, nullptr, nullptr);
+#else
+    std::string demangle =
+        itaniumDemangle(mangled_name.c_str(), nullptr, nullptr, nullptr);
+#endif
+#endif
+    return demangle;
+  }
+
   void EnableDebugOutput(bool value/* =true*/) {
     llvm::DebugFlag = value;
   }

unittests/CppInterOp/ScopeReflectionTest.cpp

@@ -8,15 +8,47 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Sema/Sema.h"
 
-#include "clang/AST/DeclBase.h"
 #include "clang/AST/ASTDumper.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclBase.h"
+#include "clang/AST/GlobalDecl.h"
 
 #include "gtest/gtest.h"
 
 using namespace TestUtils;
 using namespace llvm;
 using namespace clang;
 
+TEST(ScopeReflectionTest, DemangleSymbol) {
+  if (llvm::sys::RunningOnValgrind())
+    GTEST_SKIP() << "XFAIL due to Valgrind report";
+
+  std::string code = R"(
+    int add(int x, int y) { return x + y; }
+    int add(double x, double y) { return x + y; }
+  )";
+
+  std::vector<Decl*> Decls;
+  GetAllTopLevelDecls(code, Decls);
+  EXPECT_EQ(Decls.size(), 2);
+
+  auto Add_int = clang::GlobalDecl(static_cast<clang::NamedDecl*>(Decls[0]));
+  auto Add_double = clang::GlobalDecl(static_cast<clang::NamedDecl*>(Decls[1]));
+
+  std::string mangled_add_int;
+  std::string mangled_add_double;
+  compat::maybeMangleDeclName(Add_int, mangled_add_int);
+  compat::maybeMangleDeclName(Add_double, mangled_add_double);
+
+  std::string demangled_add_int = Cpp::Demangle(mangled_add_int);
+  std::string demangled_add_double = Cpp::Demangle(mangled_add_double);
+
+  EXPECT_EQ(demangled_add_int.substr(0, demangled_add_int.find('(')),
+            Cpp::GetQualifiedCompleteName(Decls[0]));
+  EXPECT_EQ(demangled_add_double.substr(0, demangled_add_double.find('(')),
+            Cpp::GetQualifiedCompleteName(Decls[1]));
+}
+
 TEST(ScopeReflectionTest, IsAggregate) {
   std::vector<Decl *> Decls;
   std::string code = R"(