librustc: De-`@mut` `CrateContext::externs`

src/librustc/middle/trans/base.rs

@@ -205,15 +205,21 @@ pub fn get_extern_fn(externs: &mut ExternMap, llmod: ModuleRef, name: &str,
 
 fn get_extern_rust_fn(ccx: &mut CrateContext, inputs: &[ty::t], output: ty::t,
                       name: &str, did: ast::DefId) -> ValueRef {
-    match ccx.externs.find_equiv(&name) {
+    {
+        let externs = ccx.externs.borrow();
+        match externs.get().find_equiv(&name) {
             Some(n) => return *n,
             None => ()
         }
+    }
+
     let f = decl_rust_fn(ccx, inputs, output, name);
     csearch::get_item_attrs(ccx.tcx.cstore, did, |meta_items| {
         set_llvm_fn_attrs(meta_items.iter().map(|&x| attr::mk_attr(x)).to_owned_vec(), f)
     });
-    ccx.externs.insert(name.to_owned(), f);
+
+    let mut externs = ccx.externs.borrow_mut();
+    externs.get().insert(name.to_owned(), f);
     f
 }
 
@@ -559,12 +565,16 @@ pub fn get_res_dtor(ccx: @mut CrateContext,
                                      None,
                                      ty::lookup_item_type(tcx, parent_id).ty);
         let llty = type_of_dtor(ccx, class_ty);
-        get_extern_fn(&mut ccx.externs,
+
+        {
+            let mut externs = ccx.externs.borrow_mut();
+            get_extern_fn(externs.get(),
                           ccx.llmod,
                           name,
                           lib::llvm::CCallConv,
                           llty)
         }
+    }
 }
 
 // Structural comparison: a rather involved form of glue.
@@ -865,7 +875,8 @@ pub fn trans_external_path(ccx: &mut CrateContext, did: ast::DefId, t: ty::t) ->
                     let c = foreign::llvm_calling_convention(ccx, fn_ty.abis);
                     let cconv = c.unwrap_or(lib::llvm::CCallConv);
                     let llty = type_of_fn_from_ty(ccx, t);
-                    get_extern_fn(&mut ccx.externs, ccx.llmod, name, cconv, llty)
+                    let mut externs = ccx.externs.borrow_mut();
+                    get_extern_fn(externs.get(), ccx.llmod, name, cconv, llty)
                 }
             }
         }
@@ -874,7 +885,8 @@ pub fn trans_external_path(ccx: &mut CrateContext, did: ast::DefId, t: ty::t) ->
         }
         _ => {
             let llty = type_of(ccx, t);
-            get_extern_const(&mut ccx.externs, ccx.llmod, name, llty)
+            let mut externs = ccx.externs.borrow_mut();
+            get_extern_const(externs.get(), ccx.llmod, name, llty)
         }
     }
 }

src/librustc/middle/trans/context.rs

@@ -45,7 +45,7 @@ pub struct CrateContext {
      metadata_llmod: ModuleRef,
      td: TargetData,
      tn: TypeNames,
-     externs: ExternMap,
+     externs: RefCell<ExternMap>,
      intrinsics: HashMap<&'static str, ValueRef>,
      item_vals: RefCell<HashMap<ast::NodeId, ValueRef>>,
      exp_map2: resolve::ExportMap2,
@@ -181,7 +181,7 @@ pub fn new(sess: session::Session,
                   metadata_llmod: metadata_llmod,
                   td: td,
                   tn: tn,
-                  externs: HashMap::new(),
+                  externs: RefCell::new(HashMap::new()),
                   intrinsics: intrinsics,
                   item_vals: RefCell::new(HashMap::new()),
                   exp_map2: emap2,

src/librustc/middle/trans/foreign.rs

@@ -146,8 +146,16 @@ pub fn register_foreign_item_fn(ccx: @mut CrateContext,
 
     // Create the LLVM value for the C extern fn
     let llfn_ty = lltype_for_fn_from_foreign_types(&tys);
-    let llfn = base::get_extern_fn(&mut ccx.externs, ccx.llmod,
-                                   lname, cc, llfn_ty);
+
+    let llfn;
+    {
+        let mut externs = ccx.externs.borrow_mut();
+        llfn = base::get_extern_fn(externs.get(),
+                                   ccx.llmod,
+                                   lname,
+                                   cc,
+                                   llfn_ty);
+    };
     add_argument_attributes(&tys, llfn);
 
     return llfn;