Restore int fallback

[brson]

rust-lang/rfcs#212

[vks]

Is there a reason why int is preferred over i32 as a fallback? The latter seems like a safer choice (in terms of portability).

[brendanzab]

+1 on @vks' comment.

[l0kod]

I'm in favor of i32 and f32.

[vks]

I think f64 is a more conservative choice because of the precision. Many other languages (i.e. Python) use it too.

(Personally, I've never wanted to use f32. I guess it is important when coding games, but the floating point errors are already bad enough with f64.)

[thestinger]

C / C++ implementations use i32 and f64 for the unadorned literals (int and double) in practice, although the standards specify the minimum int as i16 and floating point types are allowed to have more precision and/or a higher radix.

[l0kod]

Seems right to use f64 if it's OK for all architectures.

[alexchandel]

@vks int fallback is for ease of writing small programs, not portability; it shouldn't be used in production code. Remember, int's proper name is intptr, as C99's intptr_t, although it can store pointer differences, sizes, and array indices too, so does ptrdiff_t and size_t too.

I think int and f64 are reasonable fallback choices, although I'd rather see int renamed to intptr and have int and float just aliased to the largest native integer and floating points available (with a fallback for soft-fp systems).