From 78713a1b4ecd2ca79ce110194d76a0f71d287bd2 Mon Sep 17 00:00:00 2001
From: alemi <me@alemi.dev>
Date: Sat, 12 Oct 2024 22:25:57 +0200
Subject: [PATCH] feat: handle more complex return types

---
 macro/src/args.rs | 23 ++---------------------
 macro/src/ext.rs  | 21 +++++++++++++++++++++
 macro/src/lib.rs  |  1 +
 macro/src/ret.rs  |  8 +++++---
 4 files changed, 29 insertions(+), 24 deletions(-)
 create mode 100644 macro/src/ext.rs

diff --git a/macro/src/args.rs b/macro/src/args.rs
index 0719ec5..7bfe71e 100644
--- a/macro/src/args.rs
+++ b/macro/src/args.rs
@@ -2,6 +2,8 @@ use proc_macro2::{Span, TokenStream};
 use quote::TokenStreamExt;
 use syn::Ident;
 
+use crate::ext::bare_type;
+
 pub(crate) struct ArgumentOptions {
 	pub(crate) incoming: TokenStream,
 	pub(crate) transforming: TokenStream,
@@ -22,27 +24,6 @@ fn unpack_pat(pat: syn::Pat) -> Result<TokenStream, syn::Error> {
 	}
 }
 
-fn bare_type(ty: Box<syn::Type>) -> Option<syn::TypePath> {
-	match *ty {
-		syn::Type::Array(a) => bare_type(a.elem),
-		syn::Type::BareFn(_) => None,
-		syn::Type::ImplTrait(_) => None,
-		syn::Type::Infer(_) => None,
-		syn::Type::Macro(_) => None,
-		syn::Type::Never(_) => None,
-		syn::Type::TraitObject(_) => None,
-		syn::Type::Verbatim(_) => None,
-		syn::Type::Ptr(p) => bare_type(p.elem),
-		syn::Type::Slice(s) => bare_type(s.elem),
-		syn::Type::Tuple(t) => bare_type(Box::new(t.elems.first()?.clone())), // TODO
-		syn::Type::Group(g) => bare_type(g.elem),
-		syn::Type::Paren(p) => bare_type(p.elem),
-		syn::Type::Reference(r) => bare_type(r.elem),
-		syn::Type::Path(ty) => Some(ty),
-		_ => todo!(),
-	}
-}
-
 fn type_equals(ty: Box<syn::Type>, search: impl AsRef<str>) -> bool {
 	let Some(ty) = bare_type(ty) else { return false };
 	let Some(last) = ty.path.segments.last() else { return false };
diff --git a/macro/src/ext.rs b/macro/src/ext.rs
new file mode 100644
index 0000000..e7763a0
--- /dev/null
+++ b/macro/src/ext.rs
@@ -0,0 +1,21 @@
+
+pub(crate) fn bare_type(ty: Box<syn::Type>) -> Option<syn::TypePath> {
+	match *ty {
+		syn::Type::Array(a) => bare_type(a.elem),
+		syn::Type::BareFn(_) => None,
+		syn::Type::ImplTrait(_) => None,
+		syn::Type::Infer(_) => None,
+		syn::Type::Macro(_) => None,
+		syn::Type::Never(_) => None,
+		syn::Type::TraitObject(_) => None,
+		syn::Type::Verbatim(_) => None,
+		syn::Type::Ptr(p) => bare_type(p.elem),
+		syn::Type::Slice(s) => bare_type(s.elem),
+		syn::Type::Tuple(t) => bare_type(Box::new(t.elems.first()?.clone())), // TODO
+		syn::Type::Group(g) => bare_type(g.elem),
+		syn::Type::Paren(p) => bare_type(p.elem),
+		syn::Type::Reference(r) => bare_type(r.elem),
+		syn::Type::Path(ty) => Some(ty),
+		_ => todo!(),
+	}
+}
diff --git a/macro/src/lib.rs b/macro/src/lib.rs
index 6f3e595..f4b824e 100644
--- a/macro/src/lib.rs
+++ b/macro/src/lib.rs
@@ -2,6 +2,7 @@ mod attrs;
 mod wrapper;
 mod args;
 mod ret;
+mod ext;
 
 /// Wrap this function in in a JNI exported fn.
 #[proc_macro_attribute]
diff --git a/macro/src/ret.rs b/macro/src/ret.rs
index 5934e30..fec137a 100644
--- a/macro/src/ret.rs
+++ b/macro/src/ret.rs
@@ -2,6 +2,8 @@ use proc_macro2::{Span, TokenStream};
 use quote::ToTokens;
 use syn::{ReturnType, Type};
 
+use crate::ext::bare_type;
+
 #[derive(Clone)]
 pub(crate) struct ReturnOptions {
 	pub(crate) ty: Option<Box<Type>>,
@@ -16,8 +18,8 @@ impl ReturnOptions {
 	pub(crate) fn parse_signature(ret: &ReturnType) -> Result<Self, syn::Error> {
 		match ret {
 			syn::ReturnType::Default => Ok(Self { ty: None, result: false, void: true, pointer: false }),
-			syn::ReturnType::Type(_tok, ty) => match *ty.clone() {
-				syn::Type::Path(path) => {
+			syn::ReturnType::Type(_tok, ty) => match bare_type(ty.clone()) {
+				Some(path) => {
 					let Some(last) = path.path.segments.last() else {
 						return Err(syn::Error::new(Span::call_site(), "empty Result type is not valid"));
 					};
@@ -43,7 +45,7 @@ impl ReturnOptions {
 					let pointer = !PRIMITIVE_TYPES.iter().any(|t| last.ident == t);
 					Ok(Self { ty: Some(Box::new(Type::Path(path.clone()))), result: false, void: false, pointer })
 				},
-				_ => Err(syn::Error::new(Span::call_site(), "unsupported return type")),
+				None => Err(syn::Error::new(Span::call_site(), "unsupported return type")),
 			},
 		}
 	}