Feature: add BoundedInt trait in core::integer for min() and max()

[Amxx]

When manipulating u256, it is sometime necessary to represent the max value, similarly to how solidity does type(uint256).max. For example, some implementation of ERC-20 do not decrease the allowance in transferFrom if the current allowance is set to this max value.

Having this maximum value accessible from the corelib would save devs the burden of re-declaring this in their files.

I'm open to many different names such as uint256_max, max_uint256. If possible, uint256::max would be nice.

Note that this is declared as a function and not as a constant because Only literal constants are currently supported.

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This change is 

[spapinistarkware]

Suggestion: define a trait instead, something like

trait BoundedInt<T> {
  fn min() -> T;
  fn max() -> T;
}

implement it for u256. Then you could use BoundedInt::max(), or BoundedInt::<u256>::max() if not inferred. You will probably be able to use u256::max() in the future, though, I don't think this is currently supported.

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @Amxx and @milancermak)

[spapinistarkware]

Reviewable status: 0 of 2 files reviewed, 2 unresolved discussions (waiting on @Amxx and @milancermak)

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corelib/src/integer.cairo line 982 at r1 (raw file):

fn max_u256() -> u256 implicits(RangeCheck) nopanic {
    u256 { low: 0xffffffffffffffffffffffffffffffff_u128, high: 0xffffffffffffffffffffffffffffffff_u128 }

Line too long. Is your formatter configured correctly? WIth max line length of 100?

[Amxx]

I refactored my PR to use this trait. I implemented it for u8, u16, u32, u64, u128 and u256

Reviewable status: 0 of 2 files reviewed, 2 unresolved discussions (waiting on @milancermak and @spapinistarkware)

[spapinistarkware]

Reviewed 1 of 2 files at r2, 1 of 1 files at r3.
Reviewable status: all files reviewed (commit messages unreviewed), 3 unresolved discussions (waiting on @Amxx)

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corelib/src/integer.cairo line 987 at r3 (raw file):

}

impl BoundedU8 of BoundedInt::<u8> {

Please add #[inline(always)] above all of the impl functions. Also remove the RangeCheck.

[spapinistarkware]

Reviewed all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Amxx)

[Amxx]

Reviewable status: 0 of 3 files reviewed, 1 unresolved discussion (waiting on @milancermak and @spapinistarkware)

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corelib/src/integer.cairo line 987 at r3 (raw file):

Previously, spapinistarkware (Shahar Papini) wrote…

Please add #[inline(always)] above all of the impl functions. Also remove the RangeCheck.

done

[Amxx]

Reviewable status: 0 of 3 files reviewed, 1 unresolved discussion (waiting on @milancermak and @spapinistarkware)

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corelib/src/test.cairo line 666 at r1 (raw file):

Previously, milancermak (Milan Cermak) wrote…

    max_u256() + 1.into();

Done.

[spapinistarkware]

Reviewed 3 of 3 files at r4, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @milancermak)

[spapinistarkware]

Reviewed 1 of 1 files at r5, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @milancermak)

[spapinistarkware]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @milancermak)