From 39f67cb6ef569e63357d11f4fbb09027277832ce Mon Sep 17 00:00:00 2001
From: Jonas Platte <jplatte+git@posteo.de>
Date: Sat, 13 Nov 2021 17:38:45 +0100
Subject: [PATCH] axum-debug: Use proc-macro-crate for referencing axum in
 generated code

---
 axum-debug/Cargo.toml |  1 +
 axum-debug/src/lib.rs | 33 ++++++++++++++++++++++++++-------
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/axum-debug/Cargo.toml b/axum-debug/Cargo.toml
index b61093c2e3..f2c174b339 100644
--- a/axum-debug/Cargo.toml
+++ b/axum-debug/Cargo.toml
@@ -15,6 +15,7 @@ version = "0.1.0"
 proc-macro = true
 
 [dependencies]
+proc-macro-crate = "1.1.0"
 proc-macro2 = "1.0"
 quote = "1.0"
 syn = { version = "1.0", features = ["full"] }
diff --git a/axum-debug/src/lib.rs b/axum-debug/src/lib.rs
index d0fdba77e5..d66ff61cf9 100644
--- a/axum-debug/src/lib.rs
+++ b/axum-debug/src/lib.rs
@@ -254,11 +254,13 @@ pub fn debug_handler(_attr: TokenStream, input: TokenStream) -> TokenStream {
 #[cfg(debug_assertions)]
 mod debug {
     use proc_macro2::TokenStream;
-    use quote::{format_ident, quote_spanned};
+    use proc_macro_crate::FoundCrate;
+    use quote::{format_ident, quote, quote_spanned};
     use syn::{parse_macro_input, spanned::Spanned, FnArg, Ident, ItemFn, ReturnType, Signature};
 
     pub(crate) fn apply_debug_handler(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
         let function = parse_macro_input!(input as ItemFn);
+        let axum = import_axum();
 
         let vis = &function.vis;
         let sig = &function.sig;
@@ -284,8 +286,8 @@ mod debug {
         }
 
         let check_trait = check_trait_code(sig, &generics);
-        let check_return = check_return_code(sig, &generics);
-        let check_params = match check_params_code(sig, &generics) {
+        let check_return = check_return_code(sig, &generics, &axum);
+        let check_params = match check_params_code(sig, &generics, &axum) {
             Ok(tokens) => tokens,
             Err(err) => return err.into_compile_error().into(),
         };
@@ -336,7 +338,7 @@ mod debug {
         }
     }
 
-    fn check_trait_code(sig: &Signature, generics: &[Ident]) -> proc_macro2::TokenStream {
+    fn check_trait_code(sig: &Signature, generics: &[Ident]) -> TokenStream {
         let ident = &sig.ident;
         let span = ident.span();
 
@@ -353,7 +355,7 @@ mod debug {
         }
     }
 
-    fn check_return_code(sig: &Signature, generics: &[Ident]) -> proc_macro2::TokenStream {
+    fn check_return_code(sig: &Signature, generics: &[Ident], axum: &TokenStream) -> TokenStream {
         let span = match &sig.output {
             ReturnType::Default => sig.output.span(),
             ReturnType::Type(_, ty) => ty.span(),
@@ -368,7 +370,7 @@ mod debug {
                 where
                     F: ::std::ops::FnOnce(#(#generics),*) -> Fut,
                     Fut: ::std::future::Future<Output = Res>,
-                    Res: ::axum::response::IntoResponse,
+                    Res: #axum::response::IntoResponse,
                 {}
             }
         }
@@ -377,6 +379,7 @@ mod debug {
     fn check_params_code(
         sig: &Signature,
         generics: &[Ident],
+        axum: &TokenStream,
     ) -> Result<Vec<TokenStream>, syn::Error> {
         let ident = &sig.ident;
         generics
@@ -402,7 +405,7 @@ mod debug {
                         where
                             F: ::std::ops::FnOnce(#(#generics),*) -> Fut,
                             Fut: ::std::future::Future,
-                            #generic: ::axum::extract::FromRequest + Send,
+                            #generic: #axum::extract::FromRequest + Send,
                         {}
                     }
                 };
@@ -411,6 +414,22 @@ mod debug {
             })
             .collect()
     }
+
+    fn import_axum() -> TokenStream {
+        match proc_macro_crate::crate_name("axum") {
+            Ok(FoundCrate::Name(name)) => {
+                // Use renamed crate name if axum was renamed via `Cargo.toml`
+                let name = format_ident!("{}", name);
+                quote! { ::#name }
+            }
+            // No match arm for `Ok(FoundCrate::Itself)` because it is pretty much pointless:
+            // https://github.com/bkchr/proc-macro-crate/issues/11
+            _ => {
+                // Fall back to plain `axum`
+                quote! { ::axum }
+            }
+        }
+    }
 }
 
 #[test]