Consolidating format checking - a 4.7 concept

[Jerry DeLisle]

I am thinking about consolidating format checking between FE and runtime. I 
would like to define a work function that can be called by the FE at compile 
time and likewise used at runtime.

I am thinking that if the format string is a constant, then call the check 
routine and instead of saving the string into the dt structure, save an already 
parsed structure.  Then at runtime, we only have to traverse the structure, and 
not parse it as we do now.

Likewise, if the format string is a variable, store the string pointer as we do 
now and parse at run time, perhaps by building a direct call in the front-end to 
do this.  This fits in with 45715 as well.  I think in fact pre-parsing formats 
will give substantial performance boost, especially if we cache the format-data 
that is already parsed.

Regardless, my main motivation is not performance.  We can achieve better FE 
diagnostics and greatly simplify maintanance by having only one tokenizer etc, 
etc, etc.  It is concievable that one could match up io data elements with 
specific format specifiers at compile time and inline the format specifier with 
the transfer_*** function calls. Spooky thoughts!

A topic for the IRC meeting along with, er uh hmm, oh yea, User Defined Derived 
Type IO.

Best regards,

Jerry