Slightly simplify attribute parsing code

ruma-api-macros/src/api/attribute.rs

@@ -14,23 +14,27 @@ pub enum Meta {
 }
 
 impl Meta {
-    /// Check if the given attribute is a ruma_api attribute. If it is, parse it, if not, return
+    /// Check if the given attribute is a ruma_api attribute. If it is, parse it.
-    /// it unchanged. Panics if the argument is an invalid ruma_api attribute.
+    ///
-    pub fn from_attribute(attr: syn::Attribute) -> Result<Self, syn::Attribute> {
+    /// # Panics
+    ///
+    /// Panics if the given attribute is a ruma_api attribute, but fails to parse.
+    pub fn from_attribute(attr: &syn::Attribute) -> Option<Self> {
         match &attr.path {
             syn::Path {
                 leading_colon: None,
                 segments,
             } => {
                 if segments.len() == 1 && segments[0].ident == "ruma_api" {
-                    Ok(attr
+                    Some(
-                        .parse_args()
+                        attr.parse_args()
-                        .expect("ruma_api! could not parse request field attributes"))
+                            .expect("ruma_api! could not parse request field attributes"),
+                    )
                 } else {
-                    Err(attr)
+                    None
                 }
             }
-            _ => Err(attr),
+            _ => None,
         }
     }
 }

ruma-api-macros/src/api/request.rs

@@ -134,10 +134,10 @@ impl From<Vec<Field>> for Request {
             let mut field_kind = RequestFieldKind::Body;
             let mut header = None;
 
-            field.attrs = field.attrs.into_iter().filter_map(|attr| {
+            field.attrs.retain(|attr| {
                 let meta = match Meta::from_attribute(attr) {
-                    Ok(meta) => meta,
+                    Some(meta) => meta,
-                    Err(attr) => return Some(attr),
+                    None => return true,
                 };
 
                 match meta {
@@ -163,8 +163,8 @@ impl From<Vec<Field>> for Request {
                     }
                 }
 
-                None
+                false
-            }).collect();
+            });
 
             if field_kind == RequestFieldKind::Body {
                 assert!(

ruma-api-macros/src/api/response.rs

@@ -104,10 +104,10 @@ impl From<Vec<Field>> for Response {
             let mut field_kind = ResponseFieldKind::Body;
             let mut header = None;
 
-            field.attrs = field.attrs.into_iter().filter_map(|attr| {
+            field.attrs.retain(|attr| {
                 let meta = match Meta::from_attribute(attr) {
-                    Ok(meta) => meta,
+                    Some(meta) => meta,
-                    Err(attr) => return Some(attr),
+                    None => return true,
                 };
 
                 match meta {
@@ -131,8 +131,8 @@ impl From<Vec<Field>> for Response {
                     }
                 }
 
-                None
+                false
-            }).collect();
+            });
 
             match field_kind {
                 ResponseFieldKind::Body => {