Relax Module lifetimes and defer cloning

Author: camsteffen

src/modules.rs

@@ -51,6 +51,14 @@ impl<'a> Module<'a> {
     pub(crate) fn attrs(&self) -> &[ast::Attribute] {
         &self.inner_attr
     }
+
+    pub(crate) fn to_owned(&self) -> Module<'static> {
+        Module {
+            items: Cow::Owned((&*self.items).clone()),
+            inner_attr: self.inner_attr.clone(),
+            span: self.span,
+        }
+    }
 }
 
 /// Maps each module to the corresponding file.
@@ -150,7 +158,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
         for module_item in visitor.mods() {
             if let ast::ItemKind::Mod(_, ref sub_mod_kind) = module_item.item.kind {
                 let items = match sub_mod_kind {
-                    ast::ModKind::Loaded(items, ..) => Cow::Owned(items.clone()),
+                    ast::ModKind::Loaded(items, ..) => Cow::Borrowed(items),
                     _ => Cow::Owned(ThinVec::new()),
                 };
                 self.visit_sub_mod(
@@ -176,7 +184,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
 
             if let ast::ItemKind::Mod(_, ref sub_mod_kind) = item.kind {
                 let items = match sub_mod_kind {
-                    ast::ModKind::Loaded(items, ..) => Cow::Owned(items.clone()),
+                    ast::ModKind::Loaded(items, ..) => Cow::Borrowed(items),
                     _ => Cow::Owned(ThinVec::new()),
                 };
                 self.visit_sub_mod(&item, Module::new(item.span, items, &[]), false)?;
@@ -188,7 +196,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
     /// Visit modules from AST.
     fn visit_mod_from_ast(
         &mut self,
-        items: &'ast [rustc_ast::ptr::P<ast::Item>],
+        items: &[rustc_ast::ptr::P<ast::Item>],
     ) -> Result<(), ModuleResolutionError> {
         for item in items {
             if is_cfg_if(item) {
@@ -209,7 +217,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
     fn visit_sub_mod(
         &mut self,
         item: &'c ast::Item,
-        sub_mod: Module<'ast>,
+        sub_mod: Module<'_>,
         from_ast: bool,
     ) -> Result<(), ModuleResolutionError> {
         let old_directory = self.directory.clone();
@@ -226,7 +234,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
     fn peek_sub_mod(
         &self,
         item: &'c ast::Item,
-        sub_mod: &Module<'ast>,
+        sub_mod: &Module<'_>,
     ) -> Result<Option<SubModKind<'c, 'ast>>, ModuleResolutionError> {
         if contains_skip(&item.attrs) {
             return Ok(None);
@@ -266,7 +274,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
 
     fn visit_sub_mod_inner(
         &mut self,
-        sub_mod: Module<'ast>,
+        sub_mod: Module<'_>,
         sub_mod_kind: SubModKind<'c, 'ast>,
         from_ast: bool,
     ) -> Result<(), ModuleResolutionError> {
@@ -297,17 +305,15 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
 
     fn visit_sub_mod_after_directory_update(
         &mut self,
-        sub_mod: Module<'ast>,
+        sub_mod: Module<'_>,
         directory: Option<Directory>,
         from_ast: bool,
     ) -> Result<(), ModuleResolutionError> {
         if let Some(directory) = directory {
             self.directory = directory;
         }
         if from_ast {
-            if let Cow::Borrowed(items) = sub_mod.items {
-                self.visit_mod_from_ast(items)?;
-            }
+            self.visit_mod_from_ast(&sub_mod.items)?;
         } else {
             self.visit_mod_outside_ast(&sub_mod.items)?;
         }
@@ -319,7 +325,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
         &self,
         mod_name: symbol::Ident,
         attrs: &[ast::Attribute],
-        sub_mod: &Module<'ast>,
+        sub_mod: &Module<'_>,
     ) -> Result<Option<SubModKind<'c, 'ast>>, ModuleResolutionError> {
         let relative = match self.directory.ownership {
             DirectoryOwnership::Owned { relative } => relative,
@@ -368,7 +374,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
                         return Ok(None);
                     } else {
                         if should_insert {
-                            mods_outside_ast.push((file_path, dir_ownership, sub_mod.clone()));
+                            mods_outside_ast.push((file_path, dir_ownership, sub_mod.to_owned()));
                         }
                         return Ok(Some(SubModKind::MultiExternal(mods_outside_ast)));
                     }
@@ -389,7 +395,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
                             Module::new(span, Cow::Owned(items), &attrs),
                         ));
                         if should_insert {
-                            mods_outside_ast.push((file_path, dir_ownership, sub_mod.clone()));
+                            mods_outside_ast.push((file_path, dir_ownership, sub_mod.to_owned()));
                         }
                         Ok(Some(SubModKind::MultiExternal(mods_outside_ast)))
                     }
@@ -403,7 +409,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
                     }),
                     Err(..) => {
                         if should_insert {
-                            mods_outside_ast.push((file_path, dir_ownership, sub_mod.clone()));
+                            mods_outside_ast.push((file_path, dir_ownership, sub_mod.to_owned()));
                         }
                         Ok(Some(SubModKind::MultiExternal(mods_outside_ast)))
                     }
@@ -474,7 +480,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
     fn find_mods_outside_of_ast(
         &self,
         attrs: &[ast::Attribute],
-        sub_mod: &Module<'ast>,
+        sub_mod: &Module<'_>,
     ) -> Vec<(PathBuf, DirectoryOwnership, Module<'ast>)> {
         // Filter nested path, like `#[cfg_attr(feature = "foo", path = "bar.rs")]`.
         let mut path_visitor = visitor::PathVisitor::default();
@@ -495,7 +501,7 @@ impl<'ast, 'sess, 'c> ModResolver<'ast, 'sess> {
                 result.push((
                     actual_path,
                     DirectoryOwnership::Owned { relative: None },
-                    sub_mod.clone(),
+                    sub_mod.to_owned(),
                 ));
                 continue;
             }