From: Matt Corallo <git@bluematt.me>
Date: Tue, 29 Mar 2022 22:33:27 +0000 (+0000)
Subject: Crack `ReadableArgs` params when they're tuples
X-Git-Tag: v0.0.106.0~2^2~1
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=f05687b6d75e35ac71f96ca84dce38664d18e5cf;p=ldk-c-bindings

Crack `ReadableArgs` params when they're tuples

This replaces the special handling we'd had in 0.0.105.2 for
tuples-containing-references by instead just cracking open the
tuples and converting each field individually when calling
`ReadableArgs` where the argument is a tuple.
---

diff --git a/c-bindings-gen/src/main.rs b/c-bindings-gen/src/main.rs
index fbe3c99..d62b2a3 100644
--- a/c-bindings-gen/src/main.rs
+++ b/c-bindings-gen/src/main.rs
@@ -102,24 +102,44 @@ fn maybe_convert_trait_impl<W: std::io::Write>(w: &mut W, trait_path: &syn::Path
 
 				let mut arg_conv = Vec::new();
 				if t == "lightning::util::ser::ReadableArgs" {
-					write!(w, ", arg: ").unwrap();
 					assert!(trait_path.leading_colon.is_none());
 					let args_seg = trait_path.segments.iter().last().unwrap();
 					assert_eq!(format!("{}", args_seg.ident), "ReadableArgs");
 					if let syn::PathArguments::AngleBracketed(args) = &args_seg.arguments {
 						assert_eq!(args.args.len(), 1);
 						if let syn::GenericArgument::Type(args_ty) = args.args.iter().next().unwrap() {
-							types.write_c_type(w, args_ty, Some(generics), false);
+							macro_rules! write_arg_conv {
+								($ty: expr, $arg_name: expr) => {
+									write!(w, ", {}: ", $arg_name).unwrap();
+									types.write_c_type(w, $ty, Some(generics), false);
+
+									write!(&mut arg_conv, "\t").unwrap();
+									if types.write_from_c_conversion_new_var(&mut arg_conv, &format_ident!("{}", $arg_name), &$ty, Some(generics)) {
+										write!(&mut arg_conv, "\n\t").unwrap();
+									}
 
-							write!(&mut arg_conv, "\t").unwrap();
-							if types.write_from_c_conversion_new_var(&mut arg_conv, &format_ident!("arg"), &args_ty, Some(generics)) {
-								write!(&mut arg_conv, "\n\t").unwrap();
+									write!(&mut arg_conv, "let {}_conv = ", $arg_name).unwrap();
+									types.write_from_c_conversion_prefix(&mut arg_conv, &$ty, Some(generics));
+									write!(&mut arg_conv, "{}", $arg_name).unwrap();
+									types.write_from_c_conversion_suffix(&mut arg_conv, &$ty, Some(generics));
+									write!(&mut arg_conv, ";\n").unwrap();
+								}
 							}
 
-							write!(&mut arg_conv, "let arg_conv = ").unwrap();
-							types.write_from_c_conversion_prefix(&mut arg_conv, &args_ty, Some(generics));
-							write!(&mut arg_conv, "arg").unwrap();
-							types.write_from_c_conversion_suffix(&mut arg_conv, &args_ty, Some(generics));
+							if let syn::Type::Tuple(tup) = args_ty {
+								// Crack open tuples and make them separate arguments instead of
+								// converting the full tuple. This makes it substantially easier to
+								// reason about things like references in the tuple fields.
+								let mut arg_conv_res = Vec::new();
+								for (idx, elem) in tup.elems.iter().enumerate() {
+									let arg_name = format!("arg_{}", ('a' as u8 + idx as u8) as char);
+									write_arg_conv!(elem, arg_name);
+									write!(&mut arg_conv_res, "{}_conv{}", arg_name, if idx != tup.elems.len() - 1 { ", " } else { "" }).unwrap();
+								}
+								writeln!(&mut arg_conv, "\tlet arg_conv = ({});", String::from_utf8(arg_conv_res).unwrap()).unwrap();
+							} else {
+								write_arg_conv!(args_ty, "arg");
+							}
 						} else { unreachable!(); }
 					} else { unreachable!(); }
 				} else if t == "lightning::util::ser::MaybeReadable" {
@@ -131,7 +151,6 @@ fn maybe_convert_trait_impl<W: std::io::Write>(w: &mut W, trait_path: &syn::Path
 
 				if t == "lightning::util::ser::ReadableArgs" {
 					w.write(&arg_conv).unwrap();
-					write!(w, ";\n").unwrap();
 				}
 
 				write!(w, "\tlet res: ").unwrap();
diff --git a/c-bindings-gen/src/types.rs b/c-bindings-gen/src/types.rs
index 28e05f8..ced1f34 100644
--- a/c-bindings-gen/src/types.rs
+++ b/c-bindings-gen/src/types.rs
@@ -2714,7 +2714,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 				if !c_ty {
 					self.write_rust_path(w, generics, path);
 				} else {
-					write!(w, "{}", full_path).unwrap();
+					// We shouldn't be mapping references in types, so panic here
+					unimplemented!();
 				}
 			} else if is_ref {
 				write!(w, "&{}{}{}", if is_mut { "mut " } else { "" }, crate_pfx, full_path).unwrap();