[MIR] Handle overloaded call expressions during HIR -> HAIR translation.

src/librustc_mir/hair/cx/expr.rs

@@ -46,6 +46,26 @@ impl<'tcx> Mirror<'tcx> for &'tcx hir::Expr {
                 }
             }
 
+            hir::ExprCall(ref fun, ref args) => {
+                if cx.tcx.is_method_call(self.id) {
+                    // The callee is something implementing Fn, FnMut, or FnOnce.
+                    // Find the actual method implementation being called and
+                    // build the appropriate UFCS call expression with the
+                    // callee-object as self parameter.
+
+                    let method = method_callee(cx, self, ty::MethodCall::expr(self.id));
+                    let mut argrefs = vec![fun.to_ref()];
+                    argrefs.extend(args.iter().map(|a| a.to_ref()));
+
+                    ExprKind::Call {
+                        fun: method.to_ref(),
+                        args: argrefs,
+                    }
+                } else {
+                    ExprKind::Call { fun: fun.to_ref(), args: args.to_ref() }
+                }
+            }
+
             hir::ExprAddrOf(mutbl, ref expr) => {
                 let region = match expr_ty.sty {
                     ty::TyRef(r, _) => r,
@@ -328,8 +348,6 @@ impl<'tcx> Mirror<'tcx> for &'tcx hir::Expr {
                 ExprKind::Vec { fields: fields.to_ref() },
             hir::ExprTup(ref fields) =>
                 ExprKind::Tuple { fields: fields.to_ref() },
-            hir::ExprCall(ref fun, ref args) =>
-                ExprKind::Call { fun: fun.to_ref(), args: args.to_ref() },
         };
 
         let temp_lifetime = cx.tcx.region_maps.temporary_scope(self.id);

src/librustc_trans/trans/mir/constant.rs

@@ -89,8 +89,10 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
     {
         let ty = bcx.monomorphize(&constant.ty);
         match constant.literal {
-            mir::Literal::Item { def_id, kind, substs } =>
-                self.trans_item_ref(bcx, ty, kind, substs, def_id),
+            mir::Literal::Item { def_id, kind, substs } => {
+                let substs = bcx.tcx().mk_substs(bcx.monomorphize(&substs));
+                self.trans_item_ref(bcx, ty, kind, substs, def_id)
+            }
             mir::Literal::Value { ref value } => {
                 self.trans_constval(bcx, value, ty)
             }

src/librustc_trans/trans/mir/did.rs

@@ -21,6 +21,7 @@ use rustc::middle::traits;
 use rustc::mir::repr::ItemKind;
 use trans::common::{Block, fulfill_obligation};
 use trans::base;
+use trans::closure;
 use trans::expr;
 use trans::monomorphize;
 use trans::meth;
@@ -38,6 +39,9 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
                           substs: &'tcx Substs<'tcx>,
                           did: DefId)
                           -> OperandRef<'tcx> {
+        debug!("trans_item_ref(ty={:?}, kind={:?}, substs={:?}, did={})",
+            ty, kind, substs, bcx.tcx().item_path_str(did));
+
         match kind {
             ItemKind::Function => self.trans_fn_ref(bcx, ty, substs, did),
             ItemKind::Method => match bcx.tcx().impl_or_trait_item(did).container() {
@@ -68,6 +72,9 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
                         substs: &'tcx Substs<'tcx>,
                         did: DefId)
                         -> OperandRef<'tcx> {
+        debug!("trans_fn_ref(ty={:?}, substs={:?}, did={})",
+            ty, substs, bcx.tcx().item_path_str(did));
+
         let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
 
         if !substs.types.is_empty() || is_named_tuple_constructor(bcx.tcx(), did) {
@@ -101,9 +108,14 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
                                trait_id: DefId,
                                substs: &'tcx Substs<'tcx>)
                                -> OperandRef<'tcx> {
+        debug!("trans_static_method(ty={:?}, method={}, trait={}, substs={:?})",
+                ty,
+                bcx.tcx().item_path_str(method_id),
+                bcx.tcx().item_path_str(trait_id),
+                substs);
+
         let ccx = bcx.ccx();
         let tcx = bcx.tcx();
-        let mname = tcx.item_name(method_id);
         let subst::SeparateVecsPerParamSpace {
             types: rcvr_type,
             selfs: rcvr_self,
@@ -118,6 +130,9 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
         match vtbl {
             traits::VtableImpl(traits::VtableImplData { impl_def_id, substs: imp_substs, .. }) => {
                 assert!(!imp_substs.types.needs_infer());
+
+                let mname = tcx.item_name(method_id);
+
                 let subst::SeparateVecsPerParamSpace {
                     types: impl_type,
                     selfs: impl_self,
@@ -130,6 +145,17 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
                 let mthsubsts = tcx.mk_substs(mth.substs);
                 self.trans_fn_ref(bcx, ty, mthsubsts, mth.method.def_id)
             },
+            traits::VtableClosure(data) => {
+                let trait_closure_kind = bcx.tcx().lang_items.fn_trait_kind(trait_id).unwrap();
+                let llfn = closure::trans_closure_method(bcx.ccx(),
+                                                         data.closure_def_id,
+                                                         data.substs,
+                                                         trait_closure_kind);
+                OperandRef {
+                    ty: ty,
+                    val: OperandValue::Immediate(llfn)
+                }
+            },
             traits::VtableObject(ref data) => {
                 let idx = traits::get_vtable_index_of_object_method(tcx, data, method_id);
                 OperandRef::from_rvalue_datum(

src/test/run-pass/mir_trans_calls.rs

@@ -93,6 +93,26 @@ fn test8() -> isize {
     Two::two()
 }
 
+#[rustc_mir]
+fn test_closure<F>(f: &F, x: i32, y: i32) -> i32
+    where F: Fn(i32, i32) -> i32
+{
+    f(x, y)
+}
+
+#[rustc_mir]
+fn test_fn_object(f: &Fn(i32, i32) -> i32, x: i32, y: i32) -> i32 {
+    f(x, y)
+}
+
+#[rustc_mir]
+fn test_fn_impl(f: &&Fn(i32, i32) -> i32, x: i32, y: i32) -> i32 {
+    // This call goes through the Fn implementation for &Fn provided in
+    // core::ops::impls. It expands to a static Fn::call() that calls the
+    // Fn::call() implemenation of the object shim underneath.
+    f(x, y)
+}
+
 fn main() {
     assert_eq!(test1(1, (2, 3), &[4, 5, 6]), (1, (2, 3), &[4, 5, 6][..]));
     assert_eq!(test2(98), 98);
@@ -103,4 +123,10 @@ fn main() {
     // assert_eq!(test6(&Foo, 12367), 12367);
     assert_eq!(test7(), 1);
     assert_eq!(test8(), 2);
+
+    let closure = |x: i32, y: i32| { x + y };
+    assert_eq!(test_closure(&closure, 100, 1), 101);
+    let function_object = &closure as &Fn(i32, i32) -> i32;
+    assert_eq!(test_fn_object(function_object, 100, 2), 102);
+    assert_eq!(test_fn_impl(&function_object, 100, 3), 103);
 }