std.internal.scopebuffer: added inout for slices

update unittest

removed no-op cast

remove blank lines

std/internal/scopebuffer.d

@@ -199,7 +199,7 @@ struct ScopeBuffer(T, alias realloc = /*core.stdc.stdlib*/.realloc)
      *  A slice into the temporary buffer that is only
      *  valid until the next put() or ScopeBuffer goes out of scope.
      */
-    @system T[] opSlice(size_t lower, size_t upper)
+    @system inout(T)[] opSlice(size_t lower, size_t upper) inout
         in
         {
             assert(lower <= bufLen);
@@ -212,7 +212,7 @@ struct ScopeBuffer(T, alias realloc = /*core.stdc.stdlib*/.realloc)
     }
 
     /// ditto
-    @system T[] opSlice()
+    @system inout(T)[] opSlice() inout
     {
         assert(used <= bufLen);
         return buf[0 .. used];
@@ -222,7 +222,7 @@ struct ScopeBuffer(T, alias realloc = /*core.stdc.stdlib*/.realloc)
      * Returns:
      *  the element at index i.
      */
-    ref T opIndex(size_t i)
+    ref inout(T) opIndex(size_t i) inout
     {
         assert(i < bufLen);
         return buf[i];
@@ -352,6 +352,19 @@ unittest
     assert(s == "hellobettyeven more");
 }
 
+// const
+unittest 
+{
+    char[10] tmpbuf = void;
+    auto textbuf = ScopeBuffer!char(tmpbuf);
+    scope(exit) textbuf.free();
+    foreach(i; 0..10) textbuf.put('w');
+    const csb = textbuf;
+    const elem = csb[3];
+    const slice0 = csb[0..5];
+    const slice1 = csb[];
+}
+
 /*********************************
  * This is a slightly simpler way to create a ScopeBuffer instance
  * that uses type deduction.
@@ -391,4 +404,3 @@ unittest
     c.put(s1);
     c.put(s2);
 }
-