Re: Assignments into FUNCTAB resulting either strange output or hanging

[Andrew J. Schorr]

Interesting. The docs say:

"Any attempt to assign to an element of 'FUNCTAB' also causes a fatal error."

So the main question in my mind is why these programs don't throw a fatal
error.

bash-4.2$ ./gawk 'BEGIN {print FUNCTAB[0] = 1}'
gawk: cmd. line:1: fatal: cannot assign to elements of FUNCTAB
bash-4.2$ ./gawk 'BEGIN {print FUNCTAB[0]}'
0

So it looks like implicit assignments are not being caught properly.

Regards,
Andy

On Wed, Sep 08, 2021 at 03:47:48AM +0000, Jason C. Kwan via Bug reports only 
for gawk. wrote:
> Dear GNU,
> I've noticed a rather strange bug about FUNCTAB. Hope the attached outputs 
> suffice to reproduce the bug on your end. Thanks
> Jason
> On my version 
> gawk -VGNU Awk 5.1.0, API: 3.0 (GNU MPFR 4.1.0, GNU MP 6.2.1)Copyright (C) 
> 1989, 1991-2020 Free Software Foundation.
> running on this machine
> Summary=======           System Version: 20G95           Hardware Model: 
> MacBookPro15,2                 Board ID: Mac-827FB448E656EC26    Installed 
> Memory Size: 16GB (17179869184)                Page Size: 4096         Root 
> Volume Type: 
> SSD:1,HDD:0,FUSION:0,FDE:1,RAID:0,TINYSSD:0,IN:1,EX:0,INEX:0,APFS         
> Root Volume Size: 931GB (1000240963584)                 SSD Name: APPLE SSD 
> AP1024M             SSD Revision: 1161.100     Discrete GPU Present: 0        
>        Total Time: 147:40:15          Dashboard Start: 2021-09-01 19:41:37    
>         Dashboard End: 2021-09-07 23:21:44
> Trying to do certain kinds of math operations on it feels like hanging (the 
> final one involving multiplying b with negative infinity :
> gawk -e 'BEGIN{ a="0xFE"; print b= FUNCTAB[+a]; print a; 
> c=sprintf("%400g",b);  print sprintf(" b : \f [%s]\n c : 
> \f[%x]\n",b^(log(0)*b),b-c)  }'
> when the output field is wide enough, i get back plenty of numbers
> $ date  | gawk -e '{ a="0xFE"; print b= FUNCTAB[+a]; print a; 
> printf("%5.310e\n",b)    
> }'6.9479e-3100xFE??877557937723776738480915850953617326454614839557284805662916966568868877681050291539531252788984962450113740560184771666730980762794177452495253156543738376885465183160063273903627419386098876475375492703298816675604655744333154725916842600693687989465574994335971031957663156586178727763726702e-310
...