[cpyrt] Take template arg classes from the type when ranking overloads

src/cpyrt/CPPMethod.cxx

@@ -525,7 +525,21 @@ int cpyrt::CPPMethod::GetPriority() {
 
       // prefer more derived classes
       const std::string& clean_name = TypeManip::clean_type(aname, false);
-      interop::TCppScope_t scope = interop::GetScope(clean_name);
+      interop::TCppScope_t scope = nullptr;
+      if (clean_name.find('<') != std::string::npos &&
+          clean_name.find("initializer_list") == std::string::npos) {
+        // Resolving a template name from its spelling declares new code in
+        // the interpreter on every call, so take the class from the argument
+        // type instead, and force its definition like GetScope() does.
+        // GetScope() deliberately resolves std::initializer_list<T> as
+        // std::vector<T>, which the ranking relies on, so those still go
+        // through GetScope().
+        scope = interop::GetScopeFromType(interop::GetUnderlyingType(
+            interop::GetMethodArgType(fMethod, iarg)));
+        if (scope)
+          interop::IsComplete(scope);
+      } else
+        scope = interop::GetScope(clean_name);
       if (scope)
         priority += static_cast<int>(interop::GetNumBasesLongestBranch(scope));
 

src/interop/cppjit_interop.h

@@ -57,6 +57,8 @@ std::string ResolveName(const std::string& cppitem_name);
 RPY_EXPORTED
 TCppType_t ResolveType(TCppType_t cppitem_name);
 RPY_EXPORTED
+TCppType_t GetUnderlyingType(TCppType_t type);
+RPY_EXPORTED
 TCppType_t ResolveEnumReferenceType(TCppType_t type);
 RPY_EXPORTED
 TCppType_t ResolveEnumPointerType(TCppType_t type);

src/interop/interop_wrapper.cxx

@@ -729,6 +729,11 @@ interop::TCppScope_t interop::GetScopeFromType(TCppType_t type) {
   return Cpp::GetScopeFromType(type);
 }
 
+interop::TCppType_t interop::GetUnderlyingType(TCppType_t type) {
+  std::lock_guard<std::recursive_mutex> Lock(InterOpMutex);
+  return Cpp::GetUnderlyingType(type);
+}
+
 interop::TCppType_t interop::GetTypeFromScope(TCppScope_t klass) {
   std::lock_guard<std::recursive_mutex> Lock(InterOpMutex);
   return Cpp::GetTypeFromScope(klass);