Re: [RFC] Question on gfortran extension

[Mike Kumbera <kumbera1 at llnl dot gov>]

I think this extension was added by Asher for llnl. The examples
that failed all had the form:

integer :: a
data a /5/
data a /5/
print '(3i6)', a
end

In these cases we didn't care if the first or last data statment was used.

gfortran was the first fortran compiler to catch this bug. The compiler 
generated an ICE on this. I don't care if a warning is issued as the 
default action. It also doesn't matter if the first or last data statement 
is used since the code is not officially allowed. 

Since the all the commercial compilers (intel, pgi, pathscale and xlf)
take the code, I think we should keep the extension but issue a stern 
warning. :-) The first step to removing this nonstandard code from all 
our applications is for us to know it's in there. 

Mike


On Fri, Nov 17, 2006 at 10:21:16PM -0800, Jerry DeLisle wrote:
> Hi all,
> 
> In working on PR24978 I am looking at several test cases.  Currently the 
> following test case is accepted by gfortran as an extension:
> 
> integer :: a
> data a /5/
> data a /8/
> print '(3i6)', a
> end
> 
> The result is that the variable 'a' is assigned the value 5 because that 
> data statement is the last to be resolved even though intuitively one might 
> think the last data statement ought to take effect. (Resolution occurs in 
> reverse statement order)
> 
> This extension really goes against the F95 Standard which does not allow 
> duplicate initialization.  It is my opinion that this is a dangerous 
> extension. As implemented now, it only warns if one specifies -pedantic 
>  and errors if given -std=f95 or -std=f2003.  This can leave users open to 
> inadvertent duplicate initialization if they do not use the options.
> 
> I am wondering if we should keep this extension at all and if so should we 
> at least warn as default and error on -pedantic and/or -std=fxx?
> 
> Also, if we do keep this extension, should we keep the assignment given in 
> the last data statement rather than the first?
> 
> Regards,
> 
> Jerry