parser_item_mod: avoid cloning outer attributes

Author: Centril

src/librustc_parse/config.rs

@@ -562,14 +562,9 @@ fn is_cfg(attr: &Attribute) -> bool {
 
 /// Process the potential `cfg` attributes on a module.
 /// Also determine if the module should be included in this configuration.
-pub fn process_configure_mod(
-    sess: &ParseSess,
-    cfg_mods: bool,
-    attrs: &[Attribute],
-) -> (bool, Vec<Attribute>) {
+pub fn process_configure_mod(sess: &ParseSess, cfg_mods: bool, attrs: &mut Vec<Attribute>) -> bool {
     // Don't perform gated feature checking.
     let mut strip_unconfigured = StripUnconfigured { sess, features: None };
-    let mut attrs = attrs.to_owned();
-    strip_unconfigured.process_cfg_attrs(&mut attrs);
-    (!cfg_mods || strip_unconfigured.in_cfg(&attrs), attrs)
+    strip_unconfigured.process_cfg_attrs(attrs);
+    !cfg_mods || strip_unconfigured.in_cfg(&attrs)
 }

src/librustc_parse/parser/item.rs

@@ -168,7 +168,7 @@ impl<'a> Parser<'a> {
             self.parse_item_impl(unsafety, defaultness)?
         } else if self.eat_keyword(kw::Mod) {
             // MODULE ITEM
-            self.parse_item_mod(&attrs[..])?
+            self.parse_item_mod(attrs)?
         } else if self.eat_keyword(kw::Type) {
             // TYPE ITEM
             let (ident, ty, generics) = self.parse_type_alias()?;

src/librustc_parse/parser/module.rs

@@ -40,36 +40,34 @@ impl<'a> Parser<'a> {
     }
 
     /// Parses a `mod <foo> { ... }` or `mod <foo>;` item.
-    pub(super) fn parse_item_mod(&mut self, outer_attrs: &[Attribute]) -> PResult<'a, ItemInfo> {
-        let (in_cfg, outer_attrs) =
-            crate::config::process_configure_mod(self.sess, self.cfg_mods, outer_attrs);
+    pub(super) fn parse_item_mod(&mut self, attrs: &mut Vec<Attribute>) -> PResult<'a, ItemInfo> {
+        let in_cfg = crate::config::process_configure_mod(self.sess, self.cfg_mods, attrs);
 
         let id_span = self.token.span;
         let id = self.parse_ident()?;
-        if self.eat(&token::Semi) {
+        let (module, mut inner_attrs) = if self.eat(&token::Semi) {
             if in_cfg && self.recurse_into_file_modules {
                 // This mod is in an external file. Let's go get it!
                 let ModulePathSuccess { path, directory_ownership } =
-                    self.submod_path(id, &outer_attrs, id_span)?;
-                let (module, attrs) =
-                    self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
-                Ok((id, ItemKind::Mod(module), Some(attrs)))
+                    self.submod_path(id, &attrs, id_span)?;
+                self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?
             } else {
-                let placeholder = ast::Mod { inner: DUMMY_SP, items: Vec::new(), inline: false };
-                Ok((id, ItemKind::Mod(placeholder), None))
+                (ast::Mod { inner: DUMMY_SP, items: Vec::new(), inline: false }, Vec::new())
             }
         } else {
             let old_directory = self.directory.clone();
-            self.push_directory(id, &outer_attrs);
+            self.push_directory(id, &attrs);
 
             self.expect(&token::OpenDelim(token::Brace))?;
             let mod_inner_lo = self.token.span;
-            let attrs = self.parse_inner_attributes()?;
+            let inner_attrs = self.parse_inner_attributes()?;
             let module = self.parse_mod_items(&token::CloseDelim(token::Brace), mod_inner_lo)?;
 
             self.directory = old_directory;
-            Ok((id, ItemKind::Mod(module), Some(attrs)))
-        }
+            (module, inner_attrs)
+        };
+        attrs.append(&mut inner_attrs);
+        Ok((id, ItemKind::Mod(module), None))
     }
 
     /// Given a termination token, parses all of the items in a module.