Merge pull request #4820 from 9il/workaround16473

workaround for Issue 16473

Author: andralex

std/experimental/ndslice/slice.d

@@ -2478,7 +2478,7 @@ struct Slice(size_t _N, _Range)
         +/
         auto ref opIndexOpAssign(string op, T)(T value, size_t[N] _indexes...)
         {
-            mixin (`return _ptr[indexStride(_indexes)] ` ~ op ~ `= value;`);
+            return mixin (`_ptr[indexStride(_indexes)] ` ~ op ~ `= value`);
         }
 
         static if (doUnittest)
@@ -2727,9 +2727,10 @@ struct Slice(size_t _N, _Range)
         Increment `++` and Decrement `--` operators for a $(B fully defined index).
         +/
         auto ref opIndexUnary(string op)(size_t[N] _indexes...)
-            if (op == `++` || op == `--`)
+            // @@@workaround@@@ for Issue 16473
+            //if (op == `++` || op == `--`)
         {
-            mixin (`return ` ~ op ~ `_ptr[indexStride(_indexes)];`);
+            return mixin (`` ~ op ~ `_ptr[indexStride(_indexes)]`);
         }
 
         static if (doUnittest)
@@ -2742,6 +2743,14 @@ struct Slice(size_t _N, _Range)
             assert(a[1, 2] == 1);
         }
 
+        // Issue 16473
+        static if (doUnittest)
+        unittest
+        {
+            auto sl = slice!double(2, 5);
+            auto d = -sl[0, 1];
+        }
+
         static if (doUnittest)
         pure nothrow unittest
         {