feat: return with no expression.

[spapinistarkware]

"return;" should be equivalent to "return ():".

Add syntax to cairo_spec.rs and parser.rs.
Fix what breaks.

[gaetbout]

I'll look into it

[milancermak]

Can the same be done for break please?

[gaetbout]

If @spapinistarkware confirms it is the same complexity, I'll try

[spapinistarkware]

I think it's actualy easier to change both :)

[milancermak]

You're welcome @gaetbout 😁

[gaetbout]

Hey @spapinistarkware I'm struggling a bit (just doing return atm):
I'm modifying:

    .add_struct(StructBuilder::new("StatementReturn")
        .node("return_kw", "TerminalReturn")
        .node("expr", "Expr")
        .node("semicolon", "TerminalSemicolon")
    )

to

.add_struct(StructBuilder::new("StatementReturn")
    .node("return_kw", "TerminalReturn")
    **.node("optinal_expr", "OptionExpr")**
    .node("semicolon", "TerminalSemicolon")
)

then running the command
cargo run --bin generate-syntax
To update the AST

Then I go to parser.rs to update:

SyntaxKind::TerminalReturn => {
    let return_kw = self.take::<TerminalReturn>();
    let expr = self.parse_expr();
    let semicolon = self.parse_token::<TerminalSemicolon>();
    Some(StatementReturn::new_green(self.db, return_kw, expr, semicolon).into())
}

To update it to something like:

SyntaxKind::TerminalReturn => {
    let return_kw = self.take::<TerminalReturn>();
   let optional_expr = if self.peek().kind == SyntaxKind::**???** { // Should it be StatementExpr?
        self.parse_expr();
    } else {
        **???**
    };
    let semicolon = self.parse_token::<TerminalSemicolon>();
    Some(StatementReturn::new_green(self.db, return_kw, expr, semicolon).into())
}

I tried a bunch of stuff but can't figure out what to do 🙁 ...
Any help would be ... Helpful 😄

[spapinistarkware]

Try to check if the next token is semicolon. If not, parse expr.
After parse_expr(), do .into()
At the other branch fo something like OptionalExprNone::new_green

[spapinistarkware]

Look at how let stmt parsing works, it should be similar. When u introduce an optional expr node, u should get these nodes: OptionExpr OptionExprSome and OptionExprNone. The latter have .into() to the former. So, in the parser, at each branch of then if u create one of these and use.into()

…

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[gaetbout]

That's the thing I don't have any of those two being generated.
I must be missing something

[gaetbout]

Status update:
I have the syntax working and compiling but I'm encountering a bug in this specific case:

fn some_fn(){
   let mut a = 12;
   loop {
      if a == 14 {
         break;
      }
      a =  a + 1;
   }

error: Variable not dropped. Trait has no implementation in context: core::traits::Drop::<core::never>. Trait has no implementation in context: core::traits::Destruct::<core::never>.
 --> bool_test.cairo:25:5
    loop {
    ^****^

Looking into it.

[yuvalsw]

This is a lowering error. Assuming you didn't change anything in the lowering phase, this is unrelated.
If you break with a value, does it work?

[gaetbout]

if I break with (); it does work.
Trying to look into the lowering differences