OpenEuphoria

2. Re: literal 9223372036854775808 is negative

• Posted by ghaberek (admin) 3 months ago
• 444 views

Windows Calculator does the same thing.

Select Programmer mode and enter 1 << 63 you get -9223372036854775808.

This may not be the Euphoria bug we think it is.

-Greg

4. Re: literal 9223372036854775808 is negative

• Posted by jimcbrown (admin) 3 months ago
• 371 views

Similar to what OE does, down to the int64 (integer) and long 80bits double (atom) parts.

I think you've hit the nail on the head here. If we hit a case that causes the parser to construct as a long double (or a library call in the case of power) then it stores the value correctly as a positive number.

However, if we have a code path that sticks only to integers, then it ends up overflowing to negative.

I think it's not that straightforward. In my mind the issue here is that the parser in general would need to be able to detect when overflow happens, and automatically promote from integer to atom in those cases.

Matt Lewis did something similar way back on autopromoting from integer to atom when we want to add a delete_routine to a value that'd otherwise be fine to be stored as just a plain integer.

Only, this would be harder as it was fairly simple to detect when delete_routine was invoked and do that promotion in one place, but we might need to throw this overflow checking all over the place in the parser to catch it reliably.

Debatable... on the one hand, Pete's POV seems the more user friendly one. But to back up Greg's POV, it might end up being a huge amount of work to fix up the issue and afterwards the overall behaviour might still be considered to be inconsistent (e.g. if overflow happens in machine code or a C dll that gets called).

Wonder what Phix does differently, and if that's an easy thing to copy over into OE.

I mean, there are other workarounds. Adding a preprocessor that appends all literal integers in the source code with a ".0" so they are promoted by the parser into atoms is one idea that comes to mind.

6. Re: literal 9223372036854775808 is negative

• Posted by SDPringle 2 months ago
• 258 views

As long as we are comparing languages. Python also does the right thing as evaluating the number as positive. Euphoria:

include std/io.e 
if 9223372036854775808 < 0 then 
  puts(io:STDOUT, "Euphoria: 9223372036854775808 is negative\n") 
end if 

Output:

Euphoria: 9223372036854775808 is negative 

Python:

if 9223372036854775808 < 0:  
  print("Python: 9223372036854775808 is negative\n") 

Similar C + + fails to compile and gives the following error:

cpp.cpp:3:7: warning: integer constant is so large that it is unsigned 
    3 |   if (9223372036854775808 < 0) { 
      |       ^~~~~~~~~~~~~~~~~~~ 
 

#include <iostream> 
int main() { 
  if (9223372036854775808 < 0) { 
    std::cout << "C++: 9223372036854775808 is negative\n"; 
  } 
} 

Although I think the C + + behavior is not really desirable, I prefer what it does to what Euphoria does right now.

The number is just outside of the range of what a 64-bit Integer can hold, but if it were a valid value, its binary representation would be the same as the one used for -9223372036854775808.