[meta] Test spurrious auto parsing when looking up a TClass

reproduces root-project/root#17992

Author: dpiparo

root/meta/autoloading/avoidAutoParsing/CMakeLists.txt

@@ -0,0 +1,16 @@
+ROOTTEST_GENERATE_DICTIONARY(libDataObject dataObject.hxx 
+                             LINKDEF LinkDef.h
+                             NO_CXXMODULE
+                             FIXTURES_SETUP avoidParsingLibrary)
+
+ROOTTEST_ADD_TEST(avoidParsingSpace
+                  MACRO runAvoidParsing.C
+                  MACROARG true
+                  OUTREF avoidParsing.ref
+                  FIXTURES_REQUIRED avoidParsingLibrary)
+
+ROOTTEST_ADD_TEST(avoidParsingNoSpace
+                  MACRO runAvoidParsing.C
+                  MACROARG false
+                  OUTREF avoidParsing.ref
+                  FIXTURES_REQUIRED avoidParsingLibrary)

root/meta/autoloading/avoidAutoParsing/LinkDef.h

@@ -0,0 +1,2 @@
+#pragma link C++ class testing::InnerContent+;
+#pragma link C++ class testing::UserClass<testing::FindUsingAdvance<testing::InnerContent>>+;

root/meta/autoloading/avoidAutoParsing/avoidParsing.ref

@@ -0,0 +1 @@
+

root/meta/autoloading/avoidAutoParsing/dataObject.hxx

@@ -0,0 +1,25 @@
+#pragma once
+
+#ifdef TEST_RUNTIME
+#error "This header should not be loaded at runtime"
+#endif
+
+#include <vector>
+
+namespace testing 
+{
+   struct InnerContent {};
+   template <typename T>
+   struct FindUsingAdvance {};
+
+   using Collection = std::vector<int>;
+
+   template <typename T>
+   class UserClass 
+   {
+   public:
+      int fValue;
+      Collection fCollValue;
+   };
+}
+

root/meta/autoloading/avoidAutoParsing/runAvoidParsing.C

@@ -0,0 +1,9 @@
+#define TEST_RUNTIME 1
+
+void runAvoidParsing(bool space = true)
+{
+   if(space)
+      TClass::GetClass("testing::UserClass<testing::FindUsingAdvance<testing::InnerContent> >");
+   else
+      TClass::GetClass("testing::UserClass<testing::FindUsingAdvance<testing::InnerContent>>");
+}