[patch, libgfortran] Part 2: PR105456 Child I/O does not propage iostat

[Steve Kargl]

On Thu, Feb 29, 2024 at 09:36:43AM -0800, Jerry D wrote:
> On 2/29/24 1:47 AM, Bernhard Reutner-Fischer wrote:
> 
> > And, just for my own education, the length limitation of iomsg to 255
> > chars is not backed by the standard AFAICS, right? It's just our
> > STRERR_MAXSZ?
> 
> Yes, its what we have had for a long lone time. Once you throw an error
> things get very processor dependent. I found MSGLEN set to 100 and IOMSG_len
> to 256. Nothing magic about it.
> 

There is no restriction on the length for the iomsg-variable
that receives the generated error message.  In fact, if the
iomsg-variable has a deferred-length type parameter, then
(re)-allocation to the exact length is expected.

  F2023

  12.11.6 IOMSG= specifier

  If an error, end-of-file, or end-of-record condition occurs during
  execution of an input/output statement, iomsg-variable is assigned
  an explanatory message, as if by intrinsic assignment. If no such
  condition occurs, the definition status and value of iomsg-variable
  are unchanged.
 
character(len=23) emsg
read(fd,*,iomsg=emsg)

Here, the generated iomsg is either truncated to a length of 23
or padded with blanks to a length of 23.

character(len=:), allocatable :: emsg
read(fd,*,iomsg=emsg)

Here, emsg should have the length of whatever error message was
generated.
 
HTH

-- 
Steve