Re: [Bug fortran/32732] [Bind C] Character scalars are passed as arrays

["Christopher D. Rickett" <crickett at lanl dot gov>]

hi FX,

i did forget to CC the gcc-patches list.  thanks for forwarding it.

the problem this patch addresses is the way character args are passed 
by-value to a bind(c) procedure.  in non-bind(c), character scalars of any 
length are passed as an array type, which means an address.  this doesn't 
work for bind(c) procedures with a character dummy (of len 1) if it's 
called by a C routine.  C will promote char to an integer type node for 
passing it as a parameter.  therefore, bind(c) procedures needed to change 
both the expected type of any by-value character dummies, and the type of 
the expression for the actual.  i realize that i forgot to put a comment 
block at the top of gfc_conv_scalar_char_value; that should be done as i'm 
sure this issue will resurface.

does that help?  also, i think Steve Kargl was willing/planning to review 
the patch, so you may need to check with him.

thanks.
Chris

On Fri, 3 Aug 2007, FX Coudert wrote:

> Hi Christopher,
>
> > 2007-08-03  Christopher D. Rickett  <crickett@lanl.gov>
> >
> > 	PR fortran/32732
> > 	* trans-expr.c (gfc_conv_scalar_char_value): Convert the tree and
> > 	actual arg expressions for scalar characters passed by-value to
> > 	bind(c) routines.
> > 	(gfc_conv_function_call): Call gfc_conv_scalar_char_value.
> > 	* trans.h: Add prototype for gfc_conv_scalar_char_value.
> > 	* trans-decl.c (generate_local_decl): Convert by-value character
> > 	dummy args of bind(c) procedures using
> > 	gfc_conv_scalar_char_value.
>
> I'm willing to review that one, but I must confess that I got completely lost 
> at some point of this huge thread on the mailing-list. Perhaps you could give 
> us a short two-sentences explaining again (sorry) the reason behind the 
> patch; this could even end up as comments in the code, for future reference 
> (this business appears to be tricky, I'm sure it will resurface at some later 
> point in the compiler's very long life!).
>
> PS: I believe you forgot to CC the gcc-patches list in your initial 
> submission
>
> Thanks in advance,
> FX