Add dump option to show node

[Kamiinarii78]

Add a new dump option to show node node as
internal comment with a blacklist to ignore some
node.

gcc/rust/ChangeLog:

* ast/rust-ast-collector.cc (TokenCollector::begin_internal_comment): Add internal comment to print node beginning. (TokenCollector::end_internal_comment): Add internal comment to print node end. (TokenCollector::visit): Add the comments of the node visited. (TokenCollector::visit_closure_common): Likewise. (TokenCollector::visit_loop_common): Likewise.
* ast/rust-ast-collector.h: Add internal comment as a nes Kind.
* ast/rust-ast-dump.cc (Dump::Dump): add a Dump constructor to enable internal.
* ast/rust-ast-dump.h: Add printing of internal comment in the dump
* rust-session-manager.cc (Session::enable_dump): Activate ast dump and fill the blacklist. (Session::handle_internal_blacklist): Parse the flag to get node to be blacklisted. (Session::compile_crate): Launch ast dump internal when asked. (Session::dump_ast_pretty_internal): Call the visitor to dump the internals.
* rust-session-manager.h (struct CompileOptions): add Interal in Dump option enum.

[P-E-P]

You probably want to include "rust-system.h" instead.

[CohenArthur]

This is great work!! I've added a couple comments but they're mostly nitpick. The feature in itself is solid and you did good :) Thanks!!!!

[CohenArthur]

This pattern is nice but if forces you to write the node's "name" twice - once when you begin the comment, and once when you end it. It would be nicer and easier to maintain if this was wrapped in a lambda of some sort, e.g.:

internal_comment("VariadicParam", []() {
      if (param.has_pattern ())
    {
      visit (param.get_pattern ());
      push (Rust::Token::make (COLON, UNDEF_LOCATION));
    }
  push (Rust::Token::make (ELLIPSIS, UNDEF_LOCATION));
  });

and the code for internal_comment could be something like the following:

template <typename T> internal_comment(std::string node_name, std::function<void(T& node)> visitor) {
    begin_internal_comment(node_name);
    
    visitor();
    
    end_internal_comment(node_name);
}

note that the ergonomics might not be amazing, in which case we can look at something else like a custom destructor like what @jdupak did recently (we talked about it a little bit on Zulip)

[CohenArthur]

I would avoid using the boolean here and expose a new enum instead, which would make the code clearer

enum class Comment {
    Regular,
    Internal,
};

CollectItem (std::string comment, Comment kind = Comment::Regular) : comment(comment), kind(kind == Comment::Internal ? Kind::InternalComment : Kind::Comment) { ... }

[CohenArthur]

we can use a std::set<std::string> here for faster lookup, and for slightly better APIs as well since we can do blacklist.contains(...). also, I would call the set forbidden or excluded instead of blacklist

[CohenArthur]

These includes are prohibited here for obscure bootstrapping compiler reasons, but you can include rust-system.h instead

[CohenArthur]

what is 50 here? can we use a define or constant instead?

[CohenArthur]

same here, ideally we'd use something other than true like an enum

[CohenArthur]

Suggested change

	std::vector<std::string> internal_blacklist;
	std::set<std::string> excluded_nodes;