From 080f62916e7ea015f6e4d6c6cede3345b0c1eead Mon Sep 17 00:00:00 2001
From: Wolfgang Bumiller <w.bumiller@proxmox.com>
Date: Thu, 8 Aug 2019 14:04:27 +0200
Subject: [PATCH] macro: errors shouldn't discard the code

Otherwise we'll get even more errors.
Consider this example:

    #[api(...)]
    struct Foo { ... }
    impl MyTrait for Foo { ... }

If the #[api] macro fails and does not at least produce the
`struct Foo{}` along with its `compile_error!()` output,
then in addition to our macro errors, we'll see errors about
trying to implement `MyTrait` for an unknown thing called
`Foo`.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
 proxmox-api-macro/src/lib.rs | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/proxmox-api-macro/src/lib.rs b/proxmox-api-macro/src/lib.rs
index 88f97239..679827c5 100644
--- a/proxmox-api-macro/src/lib.rs
+++ b/proxmox-api-macro/src/lib.rs
@@ -15,9 +15,13 @@ mod types;
 mod api_macro;
 mod router_macro;
 
-fn handle_error(kind: &'static str, err: failure::Error) -> TokenStream {
+fn handle_error(mut item: proc_macro2::TokenStream, kind: &'static str, err: failure::Error) -> TokenStream {
     match err.downcast::<syn::Error>() {
-        Ok(err) => err.to_compile_error().into(),
+        Ok(err) => {
+            let err: proc_macro2::TokenStream = err.to_compile_error().into();
+            item.extend(err);
+            item.into()
+        }
         Err(err) => panic!("error in {}: {}", kind, err),
     }
 }
@@ -52,9 +56,10 @@ fn handle_error(kind: &'static str, err: failure::Error) -> TokenStream {
 /// ```
 #[proc_macro_attribute]
 pub fn api(attr: TokenStream, item: TokenStream) -> TokenStream {
-    match api_macro::api_macro(attr.into(), item.into()) {
+    let item: proc_macro2::TokenStream = item.into();
+    match api_macro::api_macro(attr.into(), item.clone()) {
         Ok(output) => output.into(),
-        Err(err) => handle_error("api definition", err),
+        Err(err) => handle_error(item, "api definition", err),
     }
 }
 
@@ -143,8 +148,9 @@ pub fn api(attr: TokenStream, item: TokenStream) -> TokenStream {
 #[proc_macro]
 pub fn router(input: TokenStream) -> TokenStream {
     // TODO...
-    match router_macro::router_macro(input.into()) {
+    let input: proc_macro2::TokenStream = input.into();
+    match router_macro::router_macro(input.clone()) {
         Ok(output) => output.into(),
-        Err(err) => handle_error("router", err),
+        Err(err) => handle_error(input, "router", err),
     }
 }