[ntuple] fix streamer field with [U]Long64_t template arg

Author: jblomer

tree/ntuple/src/RFieldMeta.cxx

@@ -1021,6 +1021,10 @@ ROOT::RStreamerField::RStreamerField(std::string_view fieldName, TClass *classp)
      fClass(classp),
      fIndex(0)
 {
+   std::string renormalizedAlias;
+   if (Internal::NeedsMetaNameAsAlias(classp->GetName(), renormalizedAlias))
+      fTypeAlias = renormalizedAlias;
+
    fTraits |= kTraitTypeChecksum;
    // For RClassField, we only check for explicit constructors and destructors and then recursively combine traits from
    // all member subfields. For RStreamerField, we treat the class as a black box and additionally need to check for

tree/ntuple/test/rfield_class.cxx

@@ -400,6 +400,10 @@ TEST(RNTuple, TClassMetaName)
    auto f5 = std::make_unique<ROOT::RField<StructUsingCollectionProxy<Long64_t>>>("f");
    EXPECT_TRUE(dynamic_cast<ROOT::RProxiedCollectionField *>(f5.get()));
    EXPECT_EQ("StructUsingCollectionProxy<Long64_t>", f5->GetTypeAlias());
+
+   ROOT::RStreamerField f6("f", "EdmWrapper<long long>");
+   EXPECT_STREQ("EdmWrapper<Long64_t>", f6.GetClass()->GetName());
+   EXPECT_EQ("EdmWrapper<Long64_t>", f6.GetTypeAlias());
 }
 
 TEST(RNTuple, StreamerInfoRecords)