3 files changed, 101 insertions, 15 deletions

diff --git a/crates/ra_hir_expand/src/ast_id_map.rs b/crates/ra_hir_expand/src/ast_id_map.rs
index a3ca302c2..d19569245 100644
--- a/crates/ra_hir_expand/src/ast_id_map.rs
+++ b/crates/ra_hir_expand/src/ast_id_map.rs
@@ -66,7 +66,7 @@ impl AstIdMap {
         // change parent's id. This means that, say, adding a new function to a
         // trait does not change ids of top-level items, which helps caching.
         bfs(node, |it| {
-            if let Some(module_item) = ast::ModuleItem::cast(it.clone()) {
+            if let Some(module_item) = ast::ModuleItem::cast(it) {
                 res.alloc(module_item.syntax());
             }
         });
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index f9d3787f6..3da137f2e 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -301,7 +301,7 @@ fn relative_file(db: &dyn AstDatabase, call_id: MacroCallId, path: &str) -> Opti
     }
 
     // Extern paths ?
-    let krate = db.relevant_crates(call_site).get(0)?.clone();
+    let krate = *db.relevant_crates(call_site).get(0)?;
     let (extern_source_id, relative_file) =
         db.crate_graph()[krate].extern_source.extern_path(path)?;
 
@@ -329,7 +329,7 @@ fn include_expand(
 
     // FIXME:
     // Handle include as expression
-    let res = parse_to_token_tree(&db.file_text(file_id.into()))
+    let res = parse_to_token_tree(&db.file_text(file_id))
         .ok_or_else(|| mbe::ExpandError::ConversionError)?
         .0;
 
@@ -340,7 +340,7 @@ fn get_env_inner(db: &dyn AstDatabase, arg_id: EagerMacroId, key: &str) -> Optio
     let call_id: MacroCallId = arg_id.into();
     let original_file = call_id.as_file().original_file(db);
 
-    let krate = db.relevant_crates(original_file).get(0)?.clone();
+    let krate = *db.relevant_crates(original_file).get(0)?;
     db.crate_graph()[krate].env.get(key)
 }
 
@@ -447,7 +447,7 @@ mod tests {
                     file_id: file_id.into(),
                 };
 
-                let id: MacroCallId = db.intern_eager_expansion(eager.into()).into();
+                let id: MacroCallId = db.intern_eager_expansion(eager).into();
                 id.as_file()
             }
         };
diff --git a/crates/ra_hir_expand/src/proc_macro.rs b/crates/ra_hir_expand/src/proc_macro.rs
index 97d1208ec..4e0e069c8 100644
--- a/crates/ra_hir_expand/src/proc_macro.rs
+++ b/crates/ra_hir_expand/src/proc_macro.rs
@@ -2,6 +2,7 @@
 
 use crate::{db::AstDatabase, LazyMacroId};
 use ra_db::{CrateId, ProcMacroId};
+use tt::buffer::{Cursor, TokenBuffer};
 
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub struct ProcMacroExpander {
@@ -36,22 +37,107 @@ impl ProcMacroExpander {
             .clone()
             .ok_or_else(|| err!("No derive macro found."))?;
 
-        let tt = remove_derive_atr(tt, &proc_macro.name)
+        let tt = remove_derive_attrs(tt)
             .ok_or_else(|| err!("Fail to remove derive for custom derive"))?;
 
         proc_macro.expander.expand(&tt, None).map_err(mbe::ExpandError::from)
     }
 }
 
-fn remove_derive_atr(tt: &tt::Subtree, _name: &str) -> Option<tt::Subtree> {
-    // FIXME: proper handle the remove derive
-    // We assume the first 2 tokens are #[derive(name)]
-    if tt.token_trees.len() > 2 {
-        let mut tt = tt.clone();
-        tt.token_trees.remove(0);
-        tt.token_trees.remove(0);
-        return Some(tt);
+fn eat_punct(cursor: &mut Cursor, c: char) -> bool {
+    if let Some(tt::TokenTree::Leaf(tt::Leaf::Punct(punct))) = cursor.token_tree() {
+        if punct.char == c {
+            *cursor = cursor.bump();
+            return true;
+        }
     }
+    false
+}
+
+fn eat_subtree(cursor: &mut Cursor, kind: tt::DelimiterKind) -> bool {
+    if let Some(tt::TokenTree::Subtree(subtree)) = cursor.token_tree() {
+        if Some(kind) == subtree.delimiter_kind() {
+            *cursor = cursor.bump_subtree();
+            return true;
+        }
+    }
+    false
+}
+
+fn eat_ident(cursor: &mut Cursor, t: &str) -> bool {
+    if let Some(tt::TokenTree::Leaf(tt::Leaf::Ident(ident))) = cursor.token_tree() {
+        if t == ident.text.as_str() {
+            *cursor = cursor.bump();
+            return true;
+        }
+    }
+    false
+}
+
+fn remove_derive_attrs(tt: &tt::Subtree) -> Option<tt::Subtree> {
+    let buffer = TokenBuffer::new(&tt.token_trees);
+    let mut p = buffer.begin();
+    let mut result = tt::Subtree::default();
+
+    while !p.eof() {
+        let curr = p;
 
-    None
+        if eat_punct(&mut p, '#') {
+            eat_punct(&mut p, '!');
+            let parent = p;
+            if eat_subtree(&mut p, tt::DelimiterKind::Bracket) {
+                if eat_ident(&mut p, "derive") {
+                    p = parent.bump();
+                    continue;
+                }
+            }
+        }
+
+        result.token_trees.push(curr.token_tree()?.clone());
+        p = curr.bump();
+    }
+
+    Some(result)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use test_utils::assert_eq_text;
+
+    #[test]
+    fn test_remove_derive_attrs() {
+        let tt = mbe::parse_to_token_tree(
+            r#"
+    #[allow(unused)]
+    #[derive(Copy)]
+    #[derive(Hello)]
+    struct A {
+        bar: u32
+    }
+"#,
+        )
+        .unwrap()
+        .0;
+        let result = format!("{:#?}", remove_derive_attrs(&tt).unwrap());
+
+        assert_eq_text!(
+            &result,
+            r#"
+SUBTREE $
+  PUNCH   # [alone] 0
+  SUBTREE [] 1
+    IDENT   allow 2
+    SUBTREE () 3
+      IDENT   unused 4
+  IDENT   struct 15
+  IDENT   A 16
+  SUBTREE {} 17
+    IDENT   bar 18
+    PUNCH   : [alone] 19
+    IDENT   u32 20
+"#
+            .trim()
+        );
+    }
 }