Feat/return empty

[gaetbout]

The return and break expression have to return something, and this something is mandatory.
In the case of returning unit type, it was mandatory to make it explicit by adding ();

return ();
break ();

With this PR it is not mandatory anymore. These will be added automatically:

return;
break;

This should fix #3034

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This change is 

[gaetbout]

@spapinistarkware Thanks for all the help you provided, I hope this fits SW requirements and solves the issue

[spapinistarkware]

Reviewed 15 of 18 files at r1, 3 of 3 files at r2, all commit messages.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @gaetbout)

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crates/cairo-lang-lowering/src/lower/mod.rs line 329 at r2 (raw file):

        | semantic::Statement::Break(semantic::StatementBreak { expr_option, stable_ptr }) => {
            log::trace!("Lowering a return | break statement.");
            match expr_option {

Only ret_var is different. Unite two branches as much as possible.

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crates/cairo-lang-lowering/src/lower/usage.rs line 102 at r2 (raw file):

                        }
                        Statement::Continue(_) => (),
                        Statement::Return(stmt) => match stmt.expr_option {

Use .map()

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crates/cairo-lang-semantic/src/expr/compute.rs line 1843 at r2 (raw file):

                return Err(ctx.diagnostics.report(return_syntax, ReturnNotAllowedInsideALoop));
            }

More code reuse. Less indentation. For now example, in both branches, I would just do
let (expr_option, expr_ty) = match ...
old code...

[gaetbout]

@spapinistarkware due to type mismatch I had to modify compute.rs.
Probably I'm missing smthng, let me know

[spapinistarkware]

Reviewed 1 of 3 files at r3, 2 of 2 files at r4, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @gaetbout)

[orizi]

Reviewed 15 of 18 files at r1, 1 of 3 files at r3, 1 of 2 files at r4, 1 of 1 files at r5, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @gaetbout)

a discussion (no related file):
please add diagnostics tests that break;and return; provides sensible diagnostics when they don't make sense.

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[gaetbout]

Hi @orizi
I hope I did what you were asking me 😅
Otherwise, could you please provide some pointer on what I should be looking at?

[orizi]

Reviewed all commit messages.
Reviewable status: 19 of 20 files reviewed, 3 unresolved discussions (waiting on @gaetbout and @spapinistarkware)

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crates/cairo-lang-semantic/src/expr/test_data/loop line 137 at r6 (raw file):

//! > module_code

//! > expected_diagnostics

some diagnostic needs to appear here - () is not a valid bool.

Code quote:

//! > expected_diagnostics

[orizi]

looks good - just one last comment :)

Reviewable status: 19 of 20 files reviewed, 2 unresolved discussions (waiting on @gaetbout and @spapinistarkware)

[gaetbout]

@orizi
As no test is red, it appears I'm missing something somewhere, isn't it?

[spapinistarkware]

Ori left a comment

Reviewable status: 19 of 20 files reviewed, 2 unresolved discussions (waiting on @gaetbout and @orizi)

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crates/cairo-lang-semantic/src/expr/compute.rs line 1864 at r6 (raw file):

                            WrongReturnType { expected_ty, actual_ty: expr_ty },
                        );
                    }

This should be outside

Code quote:

                    let expr_ty = expr.ty();
                    let expected_ty = ctx
                        .get_signature(
                            return_syntax.stable_ptr().untyped(),
                            UnsupportedOutsideOfFunctionFeatureName::ReturnStatement,
                        )?
                        .return_type;
                    if !expected_ty.is_missing(db)
                        && !expr_ty.is_missing(db)
                        && ctx.resolver.inference().conform_ty(expr_ty, expected_ty).is_err()
                    {
                        ctx.diagnostics.report(
                            &expr_syntax,
                            WrongReturnType { expected_ty, actual_ty: expr_ty },
                        );
                    }

[gaetbout]

@orizi
Should be fine now 😄
Tried to extract some code out but due to miss-matched type I couldn't...
Maybe there is a way to make the last argument matching?
(Option<Id>, TypeId, ???)
Couldn't find a matching type between OptionExprClauseEmpty and ExprClause
Edit:
For the report to work

ctx.diagnostics.report(
    &expr_syntax,
    WrongReturnType { expected_ty, actual_ty: expr_ty },
);

[orizi]

Reviewed 1 of 2 files at r7, all commit messages.
Reviewable status: 19 of 20 files reviewed, 2 unresolved discussions (waiting on @gaetbout and @spapinistarkware)

---

crates/cairo-lang-semantic/src/expr/compute.rs line 1861 at r7 (raw file):

                            WrongReturnType { expected_ty, actual_ty: expr_ty },
                        );
                    }

extract this into a closure or something just before (as it is basically the same code

Code quote:

                    let expected_ty = ctx
                        .get_signature(
                            return_syntax.stable_ptr().untyped(),
                            UnsupportedOutsideOfFunctionFeatureName::ReturnStatement,
                        )?
                        .return_type;
                    if !expected_ty.is_missing(db)
                        && !expr_ty.is_missing(db)
                        && ctx.resolver.inference().conform_ty(expr_ty, expected_ty).is_err()
                    {
                        ctx.diagnostics.report(
                            &empty_clause,
                            WrongReturnType { expected_ty, actual_ty: expr_ty },
                        );
                    }

[gaetbout]

@orizi
Should be fine now 🥳

[orizi]

Reviewed 2 of 2 files at r8, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @gaetbout)