(j3.2006) Fw: a question on MERGE and expression evaluation

Jim Xia jimxia
Thu Nov 18 21:31:43 EST 2010

> Jim's customer wants to count on
>   merge(1.0/a,0,a/=0.0)
> not working when a == 0.  Why would you want that not to work?  I would
> much prefer that it be guaranteed to work, rather than that it work or
> not work at the compiler's whim.

More accurately, it is claimed that divid-by-zero exception MUST be 
raised.  That's different from "not working when a == 0".  The first time 
when I saw this defect, my immediate reaction was "this must be a C 
programmer who hates optimizations".  However after plowing through the 
F08 for the relevant text, I did find 12.5.3 which I really don't think 
worded correctly.  I believe we should fix that paragraph.


Jim Xia

XL Fortran Compiler Test
IBM Toronto Lab at 8200 Warden Ave, Markham, On, L6G 1C7
Phone (905) 413-3444  Tie-line 313-3444
email: jimxia at ca.ibm.com
D2/YF7/8200 /MKM

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