On Monday 31 March 2008 12:58, Hubert Ritzdorf wrote:

Nevertheless, if the compiler is not sure that it can perform this optimization the compiler inserts a copy-in/copy-out. Yes, and this happens only in cases where the array in question is "non Fortran 77", for example, it is a section with a stride, it is an assumed-shape array, a pointer array, or some such. In such cases copy in/out could be required. I hear people complaining about Fortran 90 having introduced unnecessary copy in/out. I cannot see how this is true unless you are actually using a feature that was new in Fortran 90.

Such a compiler option turns off copy-in/copy-out for that source file to be compiled. It works such as an optimization flag. An optimization never affects correctness. What if copy in/out is necessary at run-time, i.e., the actual argument is not contiguous? Does this flag you mention cause those programs to abort with a run-time error? Or they crash mysteriously?

but this doesn't help the application programmer. He will look for a "portable" solution and transfer the first array element (I know, it's not guaranteed but it works). I am trying to understand is what you are actually proposing (desiring). You want a way to specify in an interface block: The actual argument must be contiguous and no copy in/out shall be performed? Should the contiguity check be compile time or run time?

Note that this has nothing to do with the TKR-matching business we've been talking about. The issue of copying is separate. Best, Aleks