From d9ee00468deb28d807bafd487d453d5b5803bf96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Wo=C5=BAniak?= <jnwznk@gmail.com>
Date: Tue, 19 Nov 2024 15:20:15 +0100
Subject: [PATCH] feat: Assert no attributes used on `self` and `ctx`

---
 sylvia-derive/src/parser/mod.rs               | 29 +++++++++++++++++++
 .../ui/attributes/payload/invalid_usage.rs    | 28 ++++++++++++++++++
 .../attributes/payload/invalid_usage.stderr   | 20 +++++++++++++
 3 files changed, 77 insertions(+)

diff --git a/sylvia-derive/src/parser/mod.rs b/sylvia-derive/src/parser/mod.rs
index 5a8e955e..e4f496e4 100644
--- a/sylvia-derive/src/parser/mod.rs
+++ b/sylvia-derive/src/parser/mod.rs
@@ -67,6 +67,35 @@ pub fn process_fields<'s, Generic>(
 where
     Generic: GetPath + PartialEq,
 {
+    // Assert no accidental usage of Sylvia attributes on `self` and `ctx` parameters.
+    sig.inputs.iter().take(2).for_each(|arg| match arg {
+        FnArg::Receiver(item) => {
+            item.attrs.iter().for_each(|attr| {
+                if SylviaAttribute::new(attr).is_none() {
+                    return;
+                }
+                emit_error!(attr.span(),
+                    "Invalid usage of Sylvia attribute.";
+                    note = "First and second arguments of the method should be `self` and `ctx` respectively.";
+                    note = "Unexpected attribute on `self` parameter."
+                );
+            });
+        }
+
+        FnArg::Typed(item) => {
+            item.attrs.iter().for_each(|attr| {
+                if SylviaAttribute::new(attr).is_none() {
+                    return;
+                }
+                emit_error!(attr.span(),
+                    "Invalid usage of Sylvia attribute.";
+                    note = "First and second arguments of the method should be `self` and `ctx` respectively.";
+                    note = "Unexpected attribute on `ctx` parameter."
+                );
+            });
+        }
+    });
+
     sig.inputs
         .iter()
         .skip(2)
diff --git a/sylvia/tests/ui/attributes/payload/invalid_usage.rs b/sylvia/tests/ui/attributes/payload/invalid_usage.rs
index 70297070..1946aa27 100644
--- a/sylvia/tests/ui/attributes/payload/invalid_usage.rs
+++ b/sylvia/tests/ui/attributes/payload/invalid_usage.rs
@@ -26,4 +26,32 @@ pub mod used_on_context {
     }
 }
 
+pub mod used_on_self {
+    use super::*;
+
+    pub struct Contract {}
+
+    #[sylvia::contract]
+    #[sv::features(replies)]
+    impl Contract {
+        pub const fn new() -> Self {
+            Self {}
+        }
+
+        #[sv::msg(instantiate)]
+        fn instantiate(&self, _ctx: InstantiateCtx) -> StdResult<Response> {
+            Ok(Response::new())
+        }
+
+        #[sv::msg(reply, reply_on=success)]
+        fn reply(
+            #[sv::payload(raw)] &self,
+            _ctx: ReplyCtx,
+            payload: Binary,
+        ) -> StdResult<Response> {
+            Ok(Response::new())
+        }
+    }
+}
+
 fn main() {}
diff --git a/sylvia/tests/ui/attributes/payload/invalid_usage.stderr b/sylvia/tests/ui/attributes/payload/invalid_usage.stderr
index 6896e3a4..5b670502 100644
--- a/sylvia/tests/ui/attributes/payload/invalid_usage.stderr
+++ b/sylvia/tests/ui/attributes/payload/invalid_usage.stderr
@@ -1,3 +1,13 @@
+error: Invalid usage of Sylvia attribute.
+
+         = note: First and second arguments of the method should be `self` and `ctx` respectively.
+         = note: Unexpected attribute on `ctx` parameter.
+
+  --> tests/ui/attributes/payload/invalid_usage.rs:23:25
+   |
+23 |         fn reply(&self, #[sv::payload(raw)] _ctx: ReplyCtx) -> StdResult<Response> {
+   |                         ^
+
 error: Missing payload parameter.
 
          = note: Expected at least one payload parameter at the end of parameter list.
@@ -6,3 +16,13 @@ error: Missing payload parameter.
    |
 23 |         fn reply(&self, #[sv::payload(raw)] _ctx: ReplyCtx) -> StdResult<Response> {
    |            ^^^^^
+
+error: Invalid usage of Sylvia attribute.
+
+         = note: First and second arguments of the method should be `self` and `ctx` respectively.
+         = note: Unexpected attribute on `self` parameter.
+
+  --> tests/ui/attributes/payload/invalid_usage.rs:48:13
+   |
+48 |             #[sv::payload(raw)] &self,
+   |             ^