refactor structurally_resolve_type

the `or_else` part was dead code.

Author: leoyvens

src/librustc_typeck/check/mod.rs

@@ -4954,41 +4954,23 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         });
     }
 
-    fn structurally_resolve_type_or_else<F>(&self, sp: Span, ty: Ty<'tcx>, f: F)
-                                            -> Ty<'tcx>
-        where F: Fn() -> Ty<'tcx>
-    {
+    // Resolves `typ` by a single level if `typ` is a type variable. If no
+    // resolution is possible, then an error is reported.
+    pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
         let mut ty = self.resolve_type_vars_with_obligations(ty);
-
         if ty.is_ty_var() {
-            let alternative = f();
-
             // If not, error.
-            if alternative.is_ty_var() || alternative.references_error() {
-                if !self.is_tainted_by_errors() {
-                    type_error_struct!(self.tcx.sess, sp, ty, E0619,
-                                       "the type of this value must be known in this context")
-                        .emit();
-                }
-                self.demand_suptype(sp, self.tcx.types.err, ty);
-                ty = self.tcx.types.err;
-            } else {
-                self.demand_suptype(sp, alternative, ty);
-                ty = alternative;
+            if !self.is_tainted_by_errors() {
+                type_error_struct!(self.tcx.sess, sp, ty, E0619,
+                                    "the type of this value must be known in this context")
+                .emit();
             }
+            self.demand_suptype(sp, self.tcx.types.err, ty);
+            ty = self.tcx.types.err;
         }
-
         ty
     }
 
-    // Resolves `typ` by a single level if `typ` is a type variable.  If no
-    // resolution is possible, then an error is reported.
-    pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
-        self.structurally_resolve_type_or_else(sp, ty, || {
-            self.tcx.types.err
-        })
-    }
-
     fn with_breakable_ctxt<F: FnOnce() -> R, R>(&self, id: ast::NodeId,
                                         ctxt: BreakableCtxt<'gcx, 'tcx>, f: F)
                                    -> (BreakableCtxt<'gcx, 'tcx>, R) {