Re: [NoW] Small float constants are silently replaced with integers

[Dirk Laurie <dirk.laurie@...>]

Op Wo. 20 Mrt. 2019 om 22:57 het Egor Skriptunoff
<egor.skriptunoff@gmail.com> geskryf:

> -- Lua 5.4 from GitHub
> local x = setmetatable({}, {
>    __add      = print,
>    __bor      = print,
>    __shl      = print,
>    __lt       = print,
>    __index    = print,
>    __newindex = print
> })
> local y
> y = x + 42       -->   table: 00000000005FADA0   42
> y = x + 42.0     -->   table: 00000000005FADA0   42.0
> y = x | 42       -->   table: 00000000005FADA0   42
> y = x | 42.0     -->   table: 00000000005FADA0   42.0
> y = x << 42      -->   table: 00000000005FADA0   42
> y = x << 42.0    -->   table: 00000000005FADA0   42.0
> y = x < 42       -->   table: 00000000005FADA0   42
> y = x < 42.0     -->   table: 00000000005FADA0   42
> y = x[42]        -->   table: 00000000005FADA0   42
> y = x[42.0]      -->   table: 00000000005FADA0   42.0
> x[42]   = y      -->   table: 00000000005FADA0   42     nil
> x[42.0] = y      -->   table: 00000000005FADA0   42.0   nil
>
> Why comparison operator ignores numeric subtype of a small float number?
> It is risky:
> while calculating result of "x < 42.0" inside a metamethod,
> an unexpected integer overflow might occur in arithmetic operation
> due to constant 42.0 (provided by user) was silently replaced with 42
>
> More consistency is required here.
> IMO, numeric subtype of arguments should always be preserved.

I have verified that Lua 5.3.5 does not do this. Good spot.