Introduce a consteval_int macro to compute integers at compile-time

[wraitii]

Fixes #3130

This introduces a Cairo plugin that converts constant expressions in constant into their actual value, so that we can write code such as the below without requiring further compiler changes. I think it's sufficient to do this in constants.

const some_value = consteval_int!((256 * 1080) & 0xfaff + 1234); // should become 14336
const some_other_value: felt252 = consteval_int!(256 - 1); // should become 255

I have a separate diff on a 'pow operator' (2**128) that I can push next if that is wanted.

---

This change is 

[spapinistarkware]

Reviewable status: 0 of 7 files reviewed, 1 unresolved discussion (waiting on @wraitii)

---

tests/bug_samples/issue2964.cairo line 23 at r1 (raw file):

    // This assumes that Drop implies Destruct and Copy implies Clone
    let mut a = GenericStruct { x: SimpleStruct { x: 1, y: 2 }, y: SimpleStruct { x: 1, y: 2 } };
    a.x.x = 24;

What is this change?

[spapinistarkware]

This alters the behaviour of the code. for example 255_u8+1-1 will work with your plugin, but fail without.
I'd rather this be explicit with an inline macro, or at the very least an annotation above the const item, that explains this does operations in the integers realm.

Reviewable status: 0 of 7 files reviewed, 3 unresolved discussions (waiting on @wraitii)

---

crates/cairo-lang-plugins/src/plugins/arithmetic.rs line 73 at r1 (raw file):

                Some(rec_compute(db, &bin_expr.lhs(db))? - rec_compute(db, &bin_expr.rhs(db))?)
            }
            ast::BinaryOperator::Div(_) => {

This might be wrong. For example, felt division is incorrect here. Are u sure u wanna support div?

---

crates/cairo-lang-plugins/src/plugins/arithmetic.rs line 76 at r1 (raw file):

                Some(rec_compute(db, &bin_expr.lhs(db))? / rec_compute(db, &bin_expr.rhs(db))?)
            }
            ast::BinaryOperator::Mod(_) => {

Same as for Div. Felts won't like this.

[spapinistarkware]

Reviewed 1 of 7 files at r1, 9 of 9 files at r2, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @wraitii)

[spapinistarkware]

Looks good to me. Let's wait for Orizi to also take a look.

Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @wraitii)

[orizi]

Reviewed 2 of 9 files at r2, all commit messages.
Reviewable status: all files reviewed, 5 unresolved discussions (waiting on @wraitii)

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 34 at r2 (raw file):

}

fn handle_constant(db: &dyn SyntaxGroup, constant_ast: &ast::ItemConstant) -> PluginResult {

doc

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 68 at r2 (raw file):

}

fn extract_consteval_macro_expression(

doc

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 93 at r2 (raw file):

}

fn rec_compute(

doc
and rename to 'compute_constant_expr'

[wraitii]

Done all inlines.

[orizi]

Reviewed 4 of 4 files at r3, all commit messages.
Reviewable status: all files reviewed, 6 unresolved discussions (waiting on @spapinistarkware and @wraitii)

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 36 at r3 (raw file):

// Rewrite a constant declaration that contains a consteval_int macro
// into a constant declaration with the computed value,
// e.g. `const a: felt252 = consteval_int!(2 * 2 * 2);` into `const a: felt252 = 8;`.

Suggestion:

/// Rewrite a constant declaration that contains a consteval_int macro
/// into a constant declaration with the computed value,
/// e.g. `const a: felt252 = consteval_int!(2 * 2 * 2);` into `const a: felt252 = 8;`.

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 71 at r3 (raw file):

}

// Extract the actual expression from the consteval_int macro, or fail with diagnostics.

Suggestion:

/// Extract the actual expression from the consteval_int macro, or fail with diagnostics.

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 98 at r3 (raw file):

// Compute the actual value of an integer expression, or fail with diagnostics.
// This computation handles arbitrary integers, unlike regular Cairo math.

Suggestion:

/// Compute the actual value of an integer expression, or fail with diagnostics.
/// This computation handles arbitrary integers, unlike regular Cairo math.

---

tests/bug_samples/issue3130.cairo line 7 at r3 (raw file):

#[test]
fn main() {}

add to bug_samples/lib.cairo

Code quote:

const a: felt252 = (4 + 2 * 3) * 256;
const b: felt252 = 0xff & (24 + 5 * 2);
const c: felt252 = -0xff & (24 + 5 * 2);
const d: felt252 = 0xff | (24 + 5 * 2);

#[test]
fn main() {}

[wraitii]

Reviewable status: 8 of 11 files reviewed, 6 unresolved discussions (waiting on @orizi and @spapinistarkware)

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 36 at r3 (raw file):

// Rewrite a constant declaration that contains a consteval_int macro
// into a constant declaration with the computed value,
// e.g. `const a: felt252 = consteval_int!(2 * 2 * 2);` into `const a: felt252 = 8;`.

Done.

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 71 at r3 (raw file):

}

// Extract the actual expression from the consteval_int macro, or fail with diagnostics.

Done.

---

crates/cairo-lang-plugins/src/plugins/consteval_int.rs line 98 at r3 (raw file):

// Compute the actual value of an integer expression, or fail with diagnostics.
// This computation handles arbitrary integers, unlike regular Cairo math.

Done.

---

tests/bug_samples/issue3130.cairo line 7 at r3 (raw file):

Previously, orizi wrote…

add to bug_samples/lib.cairo

Done, and fixed

[orizi]

Reviewed 3 of 3 files at r4, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @spapinistarkware and @wraitii)

[spapinistarkware]

Reviewed 3 of 4 files at r3, 3 of 3 files at r4, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @wraitii)

[wraitii]

@orizi @spapinistarkware Cairo_fmt wants to add a space before the 'consteval_int', but that suggestion actually crashes the Cairo compiler.

I'm not entirely sure how to fix this, it's not obvious to me where this space gets added in the formatter.

[orizi]

We probably need to fix something in the formatter. (As this is the first macro usage)
Will fix tomorrow and ping here.

Reviewable status: all files reviewed (commit messages unreviewed), all discussions resolved (waiting on @wraitii)

[orizi]

can you check again?

Reviewable status: all files reviewed (commit messages unreviewed), all discussions resolved (waiting on @wraitii)

[orizi]

Reviewed 1 of 9 files at r2, 1 of 1 files at r6, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @wraitii)