[metacling] Add cache when computing the TClingTypeInfo::Name

Author: vgvassilev

core/metacling/src/TClingTypeInfo.cxx

@@ -104,13 +104,12 @@ const char *TClingTypeInfo::Name() const
    if (!IsValid()) {
       return "";
    }
-   // Note: This *must* be static because we are returning a pointer inside it!
-   TTHREAD_TLS_DECL( std::string, buf);
-   buf.clear();
+   if (!fNameCache.empty())
+      return fNameCache.c_str();
 
    R__LOCKGUARD(gInterpreterMutex);
-   ROOT::TMetaUtils::GetFullyQualifiedTypeName(buf,fQualType,*fInterp);
-   return buf.c_str();
+   ROOT::TMetaUtils::GetFullyQualifiedTypeName(fNameCache, fQualType, *fInterp);
+   return fNameCache.c_str();
 }
 
 ////////////////////////////////////////////////////////////////////////////////

core/metacling/src/TClingTypeInfo.h

@@ -27,6 +27,8 @@
 
 #include "clang/AST/Type.h"
 
+#include <string>
+
 namespace cling {
 class Interpreter;
 }
@@ -42,6 +44,8 @@ class TClingTypeInfo {
 private:
    cling::Interpreter  *fInterp;    //Cling interpreter, we do *not* own.
    clang::QualType      fQualType;  //Clang qualified type we are querying.
+   // FIXME: Factor out in the TClingGenericInfo or a similar concept.
+   mutable std::string fNameCache;
 
 public:
 
@@ -53,6 +57,13 @@ class TClingTypeInfo {
 
    TClingTypeInfo(cling::Interpreter *interp, const char *name);
 
+   TClingTypeInfo(TClingTypeInfo& rhs)
+   {
+     fInterp = rhs.fInterp;
+     fQualType = rhs.fQualType;
+     fNameCache = ""; // we must not copy the cache.
+   }
+
    cling::Interpreter  *GetInterpreter() const { return fInterp; }
 
    clang::QualType      GetQualType() const { return fQualType; }