protected Structure maybeCreateClassStructure(Program program, Function function,
			String convention) {

		if (!THIS_CALL.equals(convention)) {
			return null;
		}

		if (namespace == null) {
			return null;
		}

		String className = namespace.getName();
		Symbol parentSymbol = function.getSymbol().getParentSymbol();
		if (parentSymbol.getSymbolType() == SymbolType.NAMESPACE) {
			try {
				NamespaceUtils.convertNamespaceToClass((Namespace) parentSymbol.getObject());
			}
			catch (InvalidInputException e) {
				throw new AssertException(e); // unexpected condition
			}
		}

		// Store class structure in parent namespace
		Demangled classNamespace = namespace.getNamespace();
		DataTypeManager dataTypeManager = program.getDataTypeManager();
		DataType existingType =
			DemangledDataType.findDataType(dataTypeManager, classNamespace, className);
		if (existingType != null && !(existingType instanceof Structure)) {
			BookmarkManager bm = program.getBookmarkManager();
			Address entry = function.getEntryPoint();
			bm.setBookmark(entry, BookmarkType.ANALYSIS, "Demangler",
				"Could not create class structure, data type already exists: " + existingType);
			return null;
		}

		Structure structure = (Structure) existingType;
		if (structure == null) {
			structure = DemangledDataType.createPlaceHolderStructure(className, classNamespace);
		}
		structure =
			(Structure) dataTypeManager.resolve(structure, DataTypeConflictHandler.DEFAULT_HANDLER);
		return structure;
	}
Check that this function is not in the std namespace.
NOTE: There could be other namespaces, but this is a key one.

@return true if it is in the std namespace
Ghidra/Features/Base/src/main/java/ghidra/app/util/demangler/DemangledFunction.java