Support definitionOrder with other declarations

[deadlocklogic]

Why DefinitionOrder is exclusive for Class and 0 for other declarations?

CppSharp/src/CppParser/Parser.cpp

Lines 3988 to 4002 in 1211272

	Declaration* Parser::WalkDeclarationDef(clang::Decl* D)
	{
	auto Decl = WalkDeclaration(D);
	if (!Decl || Decl->definitionOrder > 0)
	return Decl;
	// We store a definition order index into the declarations.
	// This is needed because declarations are added to their contexts as
	// soon as they are referenced and we need to know the original order
	// of the declarations.
	clang::RecordDecl* RecordDecl;
	if ((RecordDecl = llvm::dyn_cast<clang::RecordDecl>(D)) &&
	RecordDecl->isCompleteDefinition())
	Decl->definitionOrder = index++;
	return Decl;
	}

This is useful when we need to sort declarations based on definition order.
Because some scripting languages like pybind11: wants every base class registered before the child class, so if the base class is inside a namespace in the same TranslationUnit and the registration order is wrong, we get errors.
Currently, any declaration other than Class has its definition order set to 0.

Just a quick question: DefinitionOrder is the order of definition as parsed or as created in the AST?
Otherwise, we can use source location: line, column.

Edit:

There are only methods for line querying, none for columns: LineNumberStart/LineNumberEnd.

[tritao]

Missed this earlier... Not really sure why we only do it for classes, maybe we can relax that a little bit.

Because some scripting languages like pybind11: wants every base class registered before the child class, so if the base class is inside a namespace in the same TranslationUnit and the registration order is wrong, we get errors.

Either way, I think relying on the original declaration order for this might not be the best approach. Seems like it would be better to run some kind of ordering pass in the generator regardless. Something simple that comes to mind is building a directed graph of the declarations, then running topo sort on it to get the proper ordering.

[deadlocklogic]

Actually I am thinking of adding to the Declaration class:

public int ColumnNumberStart { get; set; }
public int ColumnNumberEnd { get; set; }

At least we can order then the concrete declarations as parsed in the translation unit.

Declaration order is important in certain binding libraries, for example with pybind11 you can't bind a class before its base classes. Therefore you must respect the same order of definition in a translation unit, and also respect the order of inclusion, so another step would be adding a pass to sort translation units by order of inclusion.

[deadlocklogic]

We still need 2 important concepts to implement:

1. Equality visitor
2. Clone visitor