Hi all,
Recently, there was some work done on defining how to handle converting
numeric literals in vim script to C integers -- basically, clamp to the
extremes of the datatype. If it would exceed the max/min value, then
just treat it as the max/min value.
However, there's nothing defining how arithmetic behaves when it would
exceed the range of the datatype. The only information in the help is:
Number A 32 or 64 bit signed number. |expr-number| *Number*
64-bit Numbers are available only when compiled with the
|+num64| feature.
Now, in C signed over/underflow is undefined behavior. If you're "lucky",
the implementation will wrap but it could just as well optimize the code
under the assumption that the code can't over/underflow.
Currently, Vim runs afoul of undefined behavior as can easily be seen
with a -fsanitize=undefined build by running
if has('num64')
echo float2nr(pow(2, 62)) * 2
else
echo float2nr(pow(2, 30)) * 2
endif
It would be nice for there to be defined behavior here for the user,
instead of exposing them to the whims of the compiler implementation.
Cheers,
--
James
GPG Key: 4096R/91BF BF4D 6956 BD5D F7B7 2D23 DFE6 91AE 331B A3DB
--
--
You received this message from the "vim_dev" maillist.
Do not top-post! Type your reply below the text you are replying to.
For more information, visit http://www.vim.org/maillist.php
---
You received this message because you are subscribed to the Google Groups
"vim_dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
