Redundant semicolons are parsed as an empty tuple semicolon statement

[topecongiro]

fn foo() {
    let _ = 3;;;;
}

Given the above example, the rustc parser used to silently drop the redundant semicolons (;;;) from the AST. However, recently the parse has changed how it treats the redundant semicolons - they are now parsed as a semicolon statement with an empty tuple:

Stmt {
    node: StmtKind::Semi(Expr {
        node: ExprKind::Tup(vec![]),
        ..
    }),
    ..
}

Found this while updating rustc-ap-syntax to 562.0.0 (which is built from the commit fc8765d) in rustfmt.

[varkor]

Ah, this is due to #62984, where we need to record the redundant semicolons for the lint. Sorry, I forgot that this would affect non-rustc parsing. We should change the representation, but I'm not sure what would be ideal. Perhaps storing the number of semicolons in StmtKind::Semi.

[GrigorenkoPV]

This should probably be closed.

REDUNDANT_SEMICOLONS is now an internal lint, which seems to be using StmtKind::Empty instead of tuples. Also rustfmt automatically removes any redundant semicolons.