rustc_mir: always emit StorageLive even without a matching StorageDead.

Author: eddyb

src/librustc_mir/build/expr/as_rvalue.rs

@@ -97,12 +97,12 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             ExprKind::Box { value } => {
                 let value = this.hir.mirror(value);
                 let result = this.temp(expr.ty, expr_span);
+                this.cfg.push(block, Statement {
+                    source_info,
+                    kind: StatementKind::StorageLive(result.clone())
+                });
                 if let Some(scope) = scope {
                     // schedule a shallow free of that memory, lest we unwind:
-                    this.cfg.push(block, Statement {
-                        source_info,
-                        kind: StatementKind::StorageLive(result.clone())
-                    });
                     this.schedule_drop(expr_span, scope, &result, value.ty);
                 }
 

src/librustc_mir/build/expr/as_temp.rs

@@ -50,7 +50,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
         let expr_ty = expr.ty.clone();
         let temp = this.temp(expr_ty.clone(), expr_span);
 
-        if !expr_ty.is_never() && temp_lifetime.is_some() {
+        if !expr_ty.is_never() {
             this.cfg.push(block, Statement {
                 source_info,
                 kind: StatementKind::StorageLive(temp.clone())