Add test for CMS fwd decl enumerator as template arg:

See cms-sw/cmsdist#6690 (comment)
Tests root-project/root#7390

cling/dict/fwd-decl-enumconstant/CMakeLists.txt

@@ -0,0 +1,10 @@
+ROOTTEST_GENERATE_REFLEX_DICTIONARY(fwdDeclEnumconstantDict
+  OPTIONS --fail_on_warnings
+  SELECTION selection.xml
+  classes.h 
+  )
+
+ROOTTEST_ADD_TEST(fwdDeclEnumconstant
+                  MACRO execfwdDeclEnumconstant.C
+                  DEPENDS fwdDeclEnumconstantDict-libgen-build
+                  LABELS roottest regression cling)

cling/dict/fwd-decl-enumconstant/Hash.h

@@ -0,0 +1,12 @@
+#ifndef DataFormats_Provenance_Hash_h
+#define DataFormats_Provenance_Hash_h
+
+namespace edm {
+
+  template <int I>
+  class Hash {
+  public:
+  };
+
+}  // namespace edm
+#endif

cling/dict/fwd-decl-enumconstant/HashedTypes.h

@@ -0,0 +1,18 @@
+#ifndef DataFormats_Provenance_HashedTypes_h
+#define DataFormats_Provenance_HashedTypes_h
+
+/// Declaration of the enum HashedTypes, used in defining several "id"
+/// classes.
+
+namespace edm {
+  enum HashedTypes {
+    ModuleDescriptionType,  // Obsolete
+    ParameterSetType,
+    ProcessHistoryType,
+    ProcessConfigurationType,
+    EntryDescriptionType,  // Obsolete
+    ParentageType
+  };
+}
+
+#endif  // DataFormats_Provenance_HashedTypes_h

cling/dict/fwd-decl-enumconstant/ParameterSetID.h

@@ -0,0 +1,24 @@
+#ifndef DataFormats_Provenance_ParameterSetID_h
+#define DataFormats_Provenance_ParameterSetID_h
+
+/*----------------------------------------------------------------------
+  
+ParameterSetID: A globally unique identifier for each collection of
+tracked parameters. Two ParameterSet objects will have equal
+ParameterSetIDs if they contain the same set of tracked parameters.
+
+We calculate the ParameterSetID from the names and values of the
+tracked parameters within a ParameterSet, currently using the MD5
+algorithm.
+
+
+----------------------------------------------------------------------*/
+
+#include "Hash.h"
+#include "HashedTypes.h"
+
+namespace edm {
+  typedef Hash<ParameterSetType> ParameterSetID;
+
+}
+#endif

cling/dict/fwd-decl-enumconstant/classes.h

@@ -0,0 +1 @@
+#include "ParameterSetID.h"

cling/dict/fwd-decl-enumconstant/execfwdDeclEnumconstant.C

@@ -0,0 +1,3 @@
+int execfwdDeclEnumconstant() {
+  return gSystem->Load("libfwdDeclEnumconstantDict_dictrflx");
+}

cling/dict/fwd-decl-enumconstant/selection.xml

@@ -0,0 +1,3 @@
+<lcgdict>
+ <class name="edm::ParameterSetID"/>
+</lcgdict>