auto merge of #13301 : erickt/rust/remove-refcell-get, r=huonw

`RefCell::get` can be a bit surprising, because it actually clones the wrapped value. This removes `RefCell::get` and replaces all the users with `RefCell::borrow()` when it can, and `RefCell::borrow().clone()` when it can't. It removes `RefCell::set` for consistency. This closes #13182.

It also fixes an infinite loop in a test when debugging is on.

src/librustc/driver/driver.rs

@@ -212,9 +212,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
     let time_passes = sess.time_passes();
 
     sess.building_library.set(session::building_library(&sess.opts, &krate));
-    sess.crate_types.set(session::collect_crate_types(sess,
-                                                      krate.attrs
-                                                           .as_slice()));
+    *sess.crate_types.borrow_mut() = session::collect_crate_types(sess, krate.attrs.as_slice());
 
     time(time_passes, "gated feature checking", (), |_|
          front::feature_gate::check_crate(sess, &krate));

src/librustc/front/test.rs

@@ -90,7 +90,7 @@ impl<'a> fold::Folder for TestHarnessGenerator<'a> {
     fn fold_item(&mut self, i: @ast::Item) -> SmallVector<@ast::Item> {
         self.cx.path.borrow_mut().push(i.ident);
         debug!("current path: {}",
-               ast_util::path_name_i(self.cx.path.get().as_slice()));
+               ast_util::path_name_i(self.cx.path.borrow().as_slice()));
 
         if is_test_fn(&self.cx, i) || is_bench_fn(&self.cx, i) {
             match i.node {
@@ -104,7 +104,7 @@ impl<'a> fold::Folder for TestHarnessGenerator<'a> {
                     debug!("this is a test function");
                     let test = Test {
                         span: i.span,
-                        path: self.cx.path.get(),
+                        path: self.cx.path.borrow().clone(),
                         bench: is_bench_fn(&self.cx, i),
                         ignore: is_ignored(&self.cx, i),
                         should_fail: should_fail(i)

src/librustc/metadata/encoder.rs

@@ -1345,7 +1345,7 @@ fn encode_info_for_items(ecx: &EncodeContext,
     }
 
     ebml_w.end_tag();
-    return /*bad*/(*index).get();
+    return /*bad*/index.borrow().clone();
 }
 
 
@@ -1365,7 +1365,7 @@ fn create_index<T:Clone + Hash + 'static>(
 
     let mut buckets_frozen = Vec::new();
     for bucket in buckets.iter() {
-        buckets_frozen.push(@/*bad*/(**bucket).get());
+        buckets_frozen.push(@/*bad*/bucket.borrow().clone());
     }
     return buckets_frozen;
 }

src/librustc/middle/dead.rs

@@ -270,7 +270,7 @@ fn create_and_seed_worklist(tcx: &ty::ctxt,
     }
 
     // Seed entry point
-    match tcx.sess.entry_fn.get() {
+    match *tcx.sess.entry_fn.borrow() {
         Some((id, _)) => worklist.push(id),
         None => ()
     }

src/librustc/middle/entry.rs

@@ -123,13 +123,13 @@ fn find_item(item: &Item, ctxt: &mut EntryContext) {
 
 fn configure_main(this: &mut EntryContext) {
     if this.start_fn.is_some() {
-        this.session.entry_fn.set(this.start_fn);
+        *this.session.entry_fn.borrow_mut() = this.start_fn;
         this.session.entry_type.set(Some(session::EntryStart));
     } else if this.attr_main_fn.is_some() {
-        this.session.entry_fn.set(this.attr_main_fn);
+        *this.session.entry_fn.borrow_mut() = this.attr_main_fn;
         this.session.entry_type.set(Some(session::EntryMain));
     } else if this.main_fn.is_some() {
-        this.session.entry_fn.set(this.main_fn);
+        *this.session.entry_fn.borrow_mut() = this.main_fn;
         this.session.entry_type.set(Some(session::EntryMain));
     } else {
         if !this.session.building_library.get() {