Method set_f_lineno

crates/vm/src/builtins/frame.rs:486–590

(&self, value: PySetterValue, vm: &VirtualMachine)

    #[pygetset(setter)]
    fn set_f_lineno(&self, value: PySetterValue, vm: &VirtualMachine) -> PyResult<()> {
        let l_new_lineno = match value {
            PySetterValue::Assign(val) => {
                let line_ref: PyIntRef = val
                    .downcast()
                    .map_err(|_| vm.new_value_error("lineno must be an integer"))?;
                line_ref
                    .try_to_primitive::<i32>(vm)
                    .map_err(|_| vm.new_value_error("lineno must be an integer"))?
            }
            PySetterValue::Delete => {
                return Err(vm.new_type_error("can't delete f_lineno attribute"));
            }
        };

        let first_line = self
            .code
            .first_line_number
            .map(|n| n.get() as i32)
            .unwrap_or(1);

        if l_new_lineno < first_line {
            return Err(vm.new_value_error(format!(
                "line {l_new_lineno} comes before the current code block"
            )));
        }

        let py_code: &PyCode = &self.code;
        let code = &py_code.code;
        let lines = mark_lines(code);

        // Find the first line >= target that has actual code
        let new_lineno = first_line_not_before(&lines, l_new_lineno);
        if new_lineno < 0 {
            return Err(vm.new_value_error(format!(
                "line {l_new_lineno} comes after the current code block"
            )));
        }

        let stacks = mark_stacks(code);
        let len = self.code.instructions.len();

        // lasti points past the current instruction (already incremented).
        // stacks[lasti - 1] gives the stack state before executing the
        // instruction that triggered this trace event, which is the current
        // evaluation stack.
        let current_lasti = self.lasti() as usize;
        let start_idx = current_lasti.saturating_sub(1);
        let start_stack = if start_idx < stacks.len() {
            stacks[start_idx]
        } else {
            OVERFLOWED
        };
        let mut best_stack = OVERFLOWED;
        let mut best_addr: i32 = -1;
        let mut err: i32 = -1;
        let mut msg = "cannot find bytecode for specified line";