Function process_assignment_lhs 

fn process_assignment_lhs<'hir>(
    ctx: &LintContext<'_, '_>,
    hir: &'hir Hir<'hir>,
    lhs: &'hir Expr<'hir>,
    assign_span: Span,
    pending: &mut HashMap<VariableId, Span>,
)

Recursively handle a plain-= assignment LHS, tracking each component as a write. For tuple destructuring (x, y) = ..., each element is processed independently.