Upgrade: address warnings -- pessimizing-move

Oh this is an interesting one...
GCC now highlights situations with `-Wpessimizing-move`,
where an overly zealous developer attempts to optimise by `std::move`,
which however prevents the compiler from applying the ''Return Value Optimisation''

The latter is mandatory since C++17, and essentially means that a value object
created within a function and then returned (by value) will actually be created
directly in the target location, possibly eliding a whole chain of
delegating value returns.

Thus: if we write `std::move(value)`, we change the returned type into an RValue reference,
and thereby ''force the compiler'' to invoke a move-ctor....

src/lib/iter-source.hpp

@@ -150,8 +150,7 @@ namespace lib {
       static iterator
       build (IterSource& sourceImpl)
         {
-          return std::move(
+          return startIteration (DataHandle{&sourceImpl, &detach_without_destroy});
-              startIteration (DataHandle{&sourceImpl, &detach_without_destroy}));
         }
       
       /** build an iterator frontend, thereby managing
@@ -163,8 +162,7 @@ namespace lib {
       static iterator
       build (IterSource* sourceImplObject)
         {
-          return std::move(
+          return startIteration (DataHandle{sourceImplObject, &destroy_managed_source});
-              startIteration (DataHandle{sourceImplObject, &destroy_managed_source}));
         }
       
       static iterator EMPTY_SOURCE;

src/stage/interact/ui-coord.hpp

@@ -491,6 +491,7 @@ namespace interact {
   
   class LocationClause;
   
+  /** @remark the result of this builder is retrieved by creating an `UICoord(builder)` */
   class UICoord::Builder
     : util::MoveOnly
     {

src/stage/interact/ui-location-solver.hpp

@@ -277,7 +277,7 @@ namespace interact {
                     // append ID of the new element to be created
                     // unless it's already there (and thus exists)
                     resolver.append (elementTypeID);
-                  return move (resolver);
+                  return move (resolver);  //////////////////////////////////////////////////////////////////TICKET #1402 : need a better solution for the builder-terminal-op. (it collides with the templated UICoord ctor)
                       // use the first suitable solution and exit
                 }
               else

src/stage/interact/view-spec-dsl.hpp

@@ -151,7 +151,7 @@ namespace interact {
         : LocatorSpec{
             LocationRule{
               LocationClause{
-                UICoord{std::move (simpleLocationSpec)}}}}
+                UICoord{std::move (simpleLocationSpec)}}}}     //////////////////////////////////////////////TICKET #1402 : how to go from Builder to UICoord? DSL design vs. constructor ambiguity
         { }
       
       operator string()  const

src/stage/model/element-access.hpp

@@ -182,7 +182,7 @@ namespace model {
   {
     UICoord::Builder targetLocation{destination.rebuild()};
     performAccessTo (targetLocation, limitCreation);
-    return targetLocation;
+    return targetLocation;   ////////////////////////////////////////////////////////////////////////////////TICKET #1402 : ambiguities related to the terminal Builder-operation and the UICoord constructors
   }
   
   

tests/library/test/test-option-test.cpp

@@ -65,7 +65,7 @@ namespace test {
           cout << "--> Testgroup=" << optparser->getTestgroup() << endl;
           cout << "--> Test-ID  =" << (isnil(testID)? "--missing--" : testID ) << endl;
           cout << "--> remaining=" << args << endl;
-          return std::move (optparser);
+          return optparser;
         }
       
       void noOptions()      { doIt (""); }