From 8ea9d939d2c44feb71e2d1c8ec390a9471b75e57 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Mon, 10 May 2021 22:54:17 +0200
Subject: Rewrite `#[derive]` removal to be based on AST

---
 crates/hir_expand/src/proc_macro.rs | 102 ------------------------------------
 1 file changed, 102 deletions(-)

(limited to 'crates/hir_expand/src/proc_macro.rs')

diff --git a/crates/hir_expand/src/proc_macro.rs b/crates/hir_expand/src/proc_macro.rs
index 75e950816..d5643393a 100644
--- a/crates/hir_expand/src/proc_macro.rs
+++ b/crates/hir_expand/src/proc_macro.rs
@@ -2,7 +2,6 @@
 
 use crate::db::AstDatabase;
 use base_db::{CrateId, ProcMacroId};
-use tt::buffer::{Cursor, TokenBuffer};
 
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub struct ProcMacroExpander {
@@ -44,9 +43,6 @@ impl ProcMacroExpander {
                     .clone()
                     .ok_or_else(|| err!("No derive macro found."))?;
 
-                let tt = remove_derive_attrs(tt)
-                    .ok_or_else(|| err!("Fail to remove derive for custom derive"))?;
-
                 // Proc macros have access to the environment variables of the invoking crate.
                 let env = &krate_graph[calling_crate].env;
 
@@ -56,101 +52,3 @@ impl ProcMacroExpander {
         }
     }
 }
-
-fn eat_punct(cursor: &mut Cursor, c: char) -> bool {
-    if let Some(tt::buffer::TokenTreeRef::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::buffer::TokenTreeRef::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::buffer::TokenTreeRef::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::from_tokens(&tt.token_trees);
-    let mut p = buffer.begin();
-    let mut result = tt::Subtree::default();
-
-    while !p.eof() {
-        let curr = p;
-
-        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()?.cloned());
-        p = curr.bump();
-    }
-
-    Some(result)
-}
-
-#[cfg(test)]
-mod tests {
-    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!(
-            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(),
-            &result
-        );
-    }
-}
-- 
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