From 1291efda04ab7cd72cf6e9628d81b55486ce4cd3 Mon Sep 17 00:00:00 2001
From: Oscar Beaumont <oscar@otbeaumont.me>
Date: Sun, 24 Dec 2023 20:26:41 +0800
Subject: [PATCH] fix #196 - fix Specta with wasm bindgen

---
 Cargo.toml                   |  1 +
 macros/src/specta.rs         | 14 ++++++++++++++
 macros/src/utils.rs          |  8 +++++---
 tests/macro/compile_error.rs |  4 ++++
 4 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index b2d21e12..9f2cd246 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -139,3 +139,4 @@ once_cell = "1.18.0"
 doc-comment = "0.3.3"
 serde = { version = "1.0.183", features = ["derive"] }
 trybuild = "1.0.82"
+wasm-bindgen = "0.2.89"
diff --git a/macros/src/specta.rs b/macros/src/specta.rs
index dffe3f9d..ceec4b53 100644
--- a/macros/src/specta.rs
+++ b/macros/src/specta.rs
@@ -10,6 +10,20 @@ pub fn attribute(item: proc_macro::TokenStream) -> syn::Result<proc_macro::Token
     let function = parse_macro_input::parse::<ItemFn>(item)?;
     let wrapper = format_fn_wrapper(&function.sig.ident);
 
+    // While using wasm_bindgen and Specta is rare, this should make the DX nicer.
+    if function.sig.unsafety.is_some()
+        && function
+            .sig
+            .ident
+            .to_string()
+            .starts_with("__wasm_bindgen_generated")
+    {
+        return Err(syn::Error::new_spanned(
+            function.sig.ident,
+            "specta: You must apply the #[specta] macro before the #[wasm_bindgen] macro",
+        ));
+    }
+
     let visibility = &function.vis;
     let (maybe_macro_export, pub_the_trait) = match &visibility {
         Visibility::Public(_) => (quote!(#[macro_export]), Default::default()),
diff --git a/macros/src/utils.rs b/macros/src/utils.rs
index c68e7042..ad232642 100644
--- a/macros/src/utils.rs
+++ b/macros/src/utils.rs
@@ -168,9 +168,11 @@ pub fn parse_attrs(attrs: &[syn::Attribute]) -> syn::Result<Vec<Attribute>> {
     for attr in attrs {
         let ident = attr
             .path
-            .get_ident()
-            .expect("Attribute path must be an ident")
-            .clone();
+            .segments
+            .last()
+            .expect("Attribute path must have at least one segment")
+            .clone()
+            .ident;
 
         // TODO: We should somehow build this up from the macro output automatically -> if not our attribute parser is applied to stuff like `allow` and that's bad.
         if !(ident == "specta"
diff --git a/tests/macro/compile_error.rs b/tests/macro/compile_error.rs
index f4209468..15260078 100644
--- a/tests/macro/compile_error.rs
+++ b/tests/macro/compile_error.rs
@@ -103,4 +103,8 @@ pub struct InvalidSpectaAttribute1;
 #[specta = "todo"]
 pub struct InvalidSpectaAttribute2;
 
+#[wasm_bindgen::prelude::wasm_bindgen]
+#[specta]
+pub fn testing() {}
+
 // TODO: https://docs.rs/trybuild/latest/trybuild/#what-to-test