Method unwind_fblock_stack

crates/codegen/src/compile.rs:1608–1689

Unwind the fblock stack, emitting cleanup code for each block preserve_tos: if true, preserve the top of stack (e.g., return value) stop_at_loop: if true, stop when encountering a loop (for break/continue)

(&mut self, preserve_tos: bool, stop_at_loop: bool)

    /// preserve_tos: if true, preserve the top of stack (e.g., return value)
    /// stop_at_loop: if true, stop when encountering a loop (for break/continue)
    fn unwind_fblock_stack(&mut self, preserve_tos: bool, stop_at_loop: bool) -> CompileResult<()> {
        // Collect the info we need, with indices for FinallyTry blocks
        #[derive(Clone)]
        enum UnwindInfo {
            Normal(FBlockInfo),
            FinallyTry {
                body: Vec<ruff_python_ast::Stmt>,
                fblock_idx: usize,
            },
        }
        let mut unwind_infos = Vec::new();

        {
            let code = self.current_code_info();
            for i in (0..code.fblock.len()).rev() {
                // Check for exception group handler (forbidden)
                if matches!(code.fblock[i].fb_type, FBlockType::ExceptionGroupHandler) {
                    return Err(self.error(CodegenErrorType::BreakContinueReturnInExceptStar));
                }

                // Stop at loop if requested
                if stop_at_loop
                    && matches!(
                        code.fblock[i].fb_type,
                        FBlockType::WhileLoop | FBlockType::ForLoop
                    )
                {
                    break;
                }

                if matches!(code.fblock[i].fb_type, FBlockType::FinallyTry) {
                    if let FBlockDatum::FinallyBody(ref body) = code.fblock[i].fb_datum {
                        unwind_infos.push(UnwindInfo::FinallyTry {
                            body: body.clone(),
                            fblock_idx: i,
                        });
                    }
                } else {
                    unwind_infos.push(UnwindInfo::Normal(code.fblock[i].clone()));
                }
            }
        }

        // Process each fblock
        for info in unwind_infos {
            match info {
                UnwindInfo::Normal(fblock_info) => {
                    self.unwind_fblock(&fblock_info, preserve_tos)?;
                }
                UnwindInfo::FinallyTry { body, fblock_idx } => {
                    // codegen_unwind_fblock(FINALLY_TRY)
                    emit!(self, PseudoInstruction::PopBlock);

                    // Temporarily remove the FinallyTry fblock so nested return/break/continue
                    // in the finally body won't see it again
                    let code = self.current_code_info();
                    let saved_fblock = code.fblock.remove(fblock_idx);