[gfortran,patch] Fix RANDOM_SEED: optional arguments and -fdefault-integer-8

[FX Coudert <fxcoudert at gmail dot com>]

Hi all,

This patch fixes various aspects of RANDOM_SEED: its handling of  
optional arguments and its use with -fdefault-integer-8, as well as a  
more generic problem with optional args to intrinsic subroutines.

  * Optional dummies used as optional args to subroutine where not  
checked for presence. This is probably rarely a problem, except when  
the dummy in question is an array (and there aren't so many intrinsic  
subroutines with option array arguments). The trans-expr.c part of  
this patch fixes this, fixing a wrong-code problem that could be seen  
on RANDOM_SEED (second part of PR30964).

  * RANDOM_SEED wrongly rejected calls where more than one argument  
is passed, even though some of these might be missing arguments. The  
real limitation is that no more than one argument be *present*. I  
removed the check from check.c (I still check for cases where more  
than one non-optional arg is passed), and installed instead a run- 
time check in the library. (This fixes the first part of PR30964.)

  * While I was looking at RANDOM_SEED, it noticed that it might not  
work nicely with -fdefault-integer-8. Indeed, in this case, the  
integer(kind=4) library routine was used and passed integer(kind=8)  
arguments! So, I've made two versions of the library routine (which  
are resolved in iresolve.c). When the default integer kind is 8, the  
seed has half the size of the int4 seed, in terms of array size, so  
that the byte-size of the seed is indeed constant. I couldn't think  
of any other choice that made sense (ignoring bytes from the seed to  
keep it a constant array size seemed... gross!)


Bootstrapped and regtested on x86_64-linux, including 4 new testcases  
(one of them tests the behaviour with -fdefault-integer-8); I also  
checked the code generated with -fdefault-integer-8. OK to commit?



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