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harn_vm/compiler/
mod.rs

1use harn_parser::{Node, SNode, TypeExpr};
2
3mod closures;
4mod concurrency;
5mod decls;
6mod error;
7mod error_handling;
8mod expressions;
9mod hitl;
10mod optimizer;
11mod patterns;
12mod pipe;
13mod state;
14mod statements;
15#[cfg(test)]
16mod tests;
17mod type_facts;
18mod yield_scan;
19
20pub use error::CompileError;
21
22use crate::chunk::{Chunk, Constant, Op};
23
24/// Jump operands are 16-bit chunk offsets (`emit_jump`, `patch_jump`,
25/// backward loop jumps), so a chunk whose code grows past `u16::MAX`
26/// bytes would silently truncate jump targets and land somewhere wild at
27/// runtime. Every finalized chunk (the program chunk and each compiled
28/// function's chunk) must pass through this guard so oversized bodies
29/// fail compilation instead of miscompiling.
30pub(crate) fn ensure_chunk_addressable(
31    chunk: &Chunk,
32    what: &str,
33    line: u32,
34) -> Result<(), CompileError> {
35    if chunk.code.len() > u16::MAX as usize {
36        return Err(CompileError {
37            message: format!(
38                "{what} compiled to {} bytes of bytecode, more than the 64 KiB a jump \
39                 operand can address; split it into smaller functions",
40                chunk.code.len()
41            ),
42            line,
43        });
44    }
45    Ok(())
46}
47
48/// Environment variable that disables optional compiler optimizations.
49///
50/// The VM still emits structurally required bytecode, such as parameter
51/// slots, but skips semantic-preserving optimizer passes. This gives tests
52/// and benchmarks a stable optimized-vs-unoptimized comparison switch.
53pub const HARN_DISABLE_OPTIMIZATIONS_ENV: &str = "HARN_DISABLE_OPTIMIZATIONS";
54
55/// Controls semantic-preserving compiler optimizations.
56#[derive(Clone, Copy, Debug, PartialEq, Eq)]
57pub struct CompilerOptions {
58    optimize: bool,
59}
60
61impl CompilerOptions {
62    pub fn optimized() -> Self {
63        Self { optimize: true }
64    }
65
66    pub fn without_optimizations() -> Self {
67        Self { optimize: false }
68    }
69
70    pub fn from_env() -> Self {
71        if std::env::var_os(HARN_DISABLE_OPTIMIZATIONS_ENV).is_some() {
72            Self::without_optimizations()
73        } else {
74            Self::optimized()
75        }
76    }
77
78    pub fn optimizations_enabled(self) -> bool {
79        self.optimize
80    }
81}
82
83impl Default for CompilerOptions {
84    fn default() -> Self {
85        Self::optimized()
86    }
87}
88
89/// Look through an `AttributedDecl` wrapper to the inner declaration.
90/// `compile_named` / `compile` use this so attributed declarations like
91/// `@test pipeline foo(...)` are still discoverable by name.
92fn peel_node(sn: &SNode) -> &Node {
93    match &sn.node {
94        Node::AttributedDecl { inner, .. } => &inner.node,
95        other => other,
96    }
97}
98
99/// Entry in the compiler's pending-finally stack. See the field-level doc on
100/// `Compiler::finally_bodies` for the unwind semantics each variant encodes.
101#[derive(Clone, Debug)]
102enum FinallyEntry {
103    Finally(Vec<SNode>),
104    CatchBarrier,
105}
106
107/// Tracks loop context for break/continue compilation.
108struct LoopContext {
109    /// Offset of the loop start (for continue).
110    start_offset: usize,
111    /// Positions of break jumps that need patching to the loop end.
112    break_patches: Vec<usize>,
113    /// True if this is a for-in loop (has an iterator to clean up on break).
114    has_iterator: bool,
115    /// Number of exception handlers active at loop entry.
116    handler_depth: usize,
117    /// Number of pending finally bodies at loop entry.
118    finally_depth: usize,
119    /// Lexical scope depth at loop entry.
120    scope_depth: usize,
121}
122
123#[derive(Clone, Copy, Debug)]
124struct LocalBinding {
125    slot: u16,
126    mutable: bool,
127}
128
129/// Compiles an AST into bytecode.
130pub struct Compiler {
131    options: CompilerOptions,
132    chunk: Chunk,
133    line: u32,
134    column: u32,
135    /// Track enum type names so PropertyAccess on them can produce EnumVariant.
136    enum_names: std::collections::HashSet<String>,
137    /// Variant name → owning enum names. Lets a bare call-shaped match
138    /// pattern (`Ok(v)`, `Some(x)`) resolve to its enum without
139    /// qualification when the variant name is unambiguous.
140    enum_variant_owners: std::collections::HashMap<String, Vec<String>>,
141    /// Track struct type names to declared field order for indexed instances.
142    struct_layouts: std::collections::HashMap<String, Vec<String>>,
143    /// Track interface names → method names for runtime enforcement.
144    interface_methods: std::collections::HashMap<String, Vec<String>>,
145    /// Stack of active loop contexts for break/continue.
146    loop_stack: Vec<LoopContext>,
147    /// Current depth of exception handlers (for cleanup on break/continue).
148    handler_depth: usize,
149    /// Stack of pending finally bodies plus catch-handler barriers for
150    /// unwind-aware lowering of `throw`, `return`, `break`, and `continue`.
151    ///
152    /// A `Finally` entry is a pending finally body that must execute when
153    /// control exits its enclosing try block. A `CatchBarrier` marks the
154    /// boundary of an active `try/catch` handler: throws emitted inside
155    /// the try body are caught locally, so pre-running finallys *beyond*
156    /// the barrier would wrongly fire side effects for outer blocks the
157    /// throw never actually escapes. Throw lowering stops at the innermost
158    /// barrier; `return`/`break`/`continue`, which do transfer past local
159    /// handlers, still run every pending `Finally` up to their target.
160    finally_bodies: Vec<FinallyEntry>,
161    /// Counter for unique temp variable names.
162    temp_counter: usize,
163    /// Number of lexical block scopes currently active in this compiled frame.
164    scope_depth: usize,
165    /// Top-level `type` aliases, used to lower `schema_of(T)` and
166    /// `output_schema: T` into constant JSON-Schema dicts at compile time.
167    type_aliases: std::collections::HashMap<String, TypeExpr>,
168    /// Lightweight compiler-side type facts used only for conservative
169    /// bytecode specialization. This mirrors lexical scopes and is separate
170    /// from the parser's diagnostic type checker so compile-only callers keep
171    /// working without a required type-check pass.
172    type_scopes: Vec<std::collections::HashMap<String, TypeExpr>>,
173    /// `(span.start, span.end)` of every mutable binding (`var` / `for`-item)
174    /// proven *monomorphic*: its value keeps a single primitive type across its
175    /// initializer and every reassignment in scope. Only these bindings may
176    /// carry an initializer-inferred primitive type fact into typed-opcode
177    /// specialization (`AddInt`, `LessInt`, …), which hard-errors on a runtime
178    /// operand-type mismatch. A mutable binding that is reassigned through an
179    /// `any`-typed (or otherwise non-matching) value is *not* recorded here, so
180    /// the compiler keeps it on the generic adaptive path that re-checks operand
181    /// shapes at runtime — see [`Compiler::record_monomorphic_var_bindings`].
182    /// Populated per lexical scope before that scope's statements are compiled;
183    /// keyed by byte span because `Span` is not `Hash`.
184    monomorphic_bindings: std::collections::HashSet<(usize, usize)>,
185    /// Current-chunk string constant index. This avoids repeatedly scanning the
186    /// constant pool while compiling name-heavy scripts.
187    string_constants: std::collections::HashMap<String, u16>,
188    /// Lexical variable slots for the current compiled frame. The compiler
189    /// only consults this for names declared inside the current function-like
190    /// body; all unresolved names stay on the existing dynamic/name path.
191    local_scopes: Vec<std::collections::HashMap<String, LocalBinding>>,
192    /// True when this compiler is emitting code outside any function-like
193    /// scope (module top-level statements). `try*` is rejected here
194    /// because the rethrow has no enclosing function to live in.
195    /// Pipeline bodies and nested `Compiler::new()` instances (fn,
196    /// closure, tool, etc.) flip this to false before compiling.
197    module_level: bool,
198    /// Names referenced inside a nested closure of the body this compiler is
199    /// emitting. A mutable (`let`) local whose name is in this set is captured
200    /// by a closure, so it is boxed into a shared cell (`Op::DefCell`) rather
201    /// than a by-value local slot — this is what makes closure capture
202    /// **by reference** (harn#4479). Recomputed per function-like body via
203    /// [`Compiler::seed_captured_idents`]; an over-approximation (a shadowed or
204    /// read-only capture may be boxed) is safe — it only forgoes the slot fast
205    /// path for that one local. `const` locals and params are immutable and
206    /// never boxed.
207    captured_idents: std::collections::HashSet<String>,
208}
209
210impl Compiler {
211    /// Compile a single AST node. Most arm bodies live in per-category
212    /// submodules (expressions, statements, closures, decls, patterns,
213    /// error_handling, concurrency); this function is a thin dispatcher.
214    fn compile_node(&mut self, snode: &SNode) -> Result<(), CompileError> {
215        self.line = snode.span.line as u32;
216        self.column = snode.span.column as u32;
217        self.chunk.set_column(self.column);
218        if self.options.optimizations_enabled() {
219            if let Some(folded) = optimizer::fold_constant_expr(snode) {
220                if folded.node != snode.node {
221                    return self.compile_node(&folded);
222                }
223            }
224        }
225        match &snode.node {
226            Node::IntLiteral(n) => {
227                let idx = self.chunk.add_constant(Constant::Int(*n));
228                self.chunk.emit_u16(Op::Constant, idx, self.line);
229            }
230            Node::FloatLiteral(n) => {
231                let idx = self.chunk.add_constant(Constant::Float(*n));
232                self.chunk.emit_u16(Op::Constant, idx, self.line);
233            }
234            Node::StringLiteral(s) | Node::RawStringLiteral(s) => {
235                let idx = self.string_constant(s);
236                self.chunk.emit_u16(Op::Constant, idx, self.line);
237            }
238            Node::BoolLiteral(true) => self.chunk.emit(Op::True, self.line),
239            Node::BoolLiteral(false) => self.chunk.emit(Op::False, self.line),
240            Node::NilLiteral => self.chunk.emit(Op::Nil, self.line),
241            Node::DurationLiteral(ms) => {
242                let ms = i64::try_from(*ms).map_err(|_| CompileError {
243                    message: "duration literal is too large".to_string(),
244                    line: self.line,
245                })?;
246                let idx = self.chunk.add_constant(Constant::Duration(ms));
247                self.chunk.emit_u16(Op::Constant, idx, self.line);
248            }
249            Node::Identifier(name) => {
250                if let Some(schema) = self.schema_value_for_alias(name) {
251                    self.emit_vm_value_literal(&schema);
252                    return Ok(());
253                }
254                self.emit_get_binding(name);
255            }
256            Node::LetBinding { pattern, value, .. } => {
257                let binding_type = match &snode.node {
258                    Node::LetBinding {
259                        type_ann: Some(type_ann),
260                        ..
261                    } => Some(type_ann.clone()),
262                    _ => self.infer_expr_type(value),
263                };
264                self.compile_node(value)?;
265                self.compile_destructuring(pattern, true)?;
266                // A `let` is reassignable, so its initializer-inferred primitive
267                // type is only safe for typed-opcode specialization when the
268                // binding is provably monomorphic (proven by
269                // `record_monomorphic_var_bindings`, run before this scope's
270                // statements). Otherwise drop the primitive fact so arithmetic
271                // stays on the generic adaptive path, which re-checks operand
272                // shapes at runtime instead of hard-committing to `AddInt` etc.
273                let binding_type = self.gate_mutable_primitive_type(snode.span, binding_type);
274                self.record_binding_type(pattern, binding_type.clone());
275                self.maybe_register_owned_drop(pattern, binding_type.as_ref(), snode.span);
276            }
277            Node::ConstBinding { pattern, value, .. } => {
278                // `const` is an immutable binding. When its initializer is in
279                // the pure const-eval subset over a plain identifier, the
280                // typechecker has already folded it; either way the VM
281                // re-evaluates the same expression, producing the folded value
282                // byte-for-byte. Lowered immutable (destructuring allowed).
283                let binding_type = match &snode.node {
284                    Node::ConstBinding {
285                        type_ann: Some(type_ann),
286                        ..
287                    } => Some(type_ann.clone()),
288                    _ => self.infer_expr_type(value),
289                };
290                self.compile_node(value)?;
291                self.compile_destructuring(pattern, false)?;
292                self.record_binding_type(pattern, binding_type.clone());
293                self.maybe_register_owned_drop(pattern, binding_type.as_ref(), snode.span);
294            }
295            Node::Assignment {
296                target, value, op, ..
297            } => {
298                self.compile_assignment(target, value, op)?;
299            }
300            Node::BinaryOp { op, left, right } => {
301                self.compile_binary_op(op, left, right)?;
302            }
303            Node::UnaryOp { op, operand } => {
304                self.compile_node(operand)?;
305                match op.as_str() {
306                    "-" => self.chunk.emit(Op::Negate, self.line),
307                    "!" => self.chunk.emit(Op::Not, self.line),
308                    _ => {}
309                }
310            }
311            Node::NonNullAssert { operand } => {
312                // `expr!` — identity when present, throws when `nil`. Leaves the
313                // (non-nil) value on the stack. `JumpIfFalse` peeks, so the
314                // `is_nil` bool is popped on both paths.
315                self.compile_node(operand)?; // [value]
316                self.chunk.emit(Op::Dup, self.line); // [value, value]
317                self.chunk.emit(Op::Nil, self.line); // [value, value, nil]
318                self.chunk.emit(Op::Equal, self.line); // [value, is_nil]
319                let present_jump = self.chunk.emit_jump(Op::JumpIfFalse, self.line);
320                // nil path: drop the bool, throw a structured message.
321                self.chunk.emit(Op::Pop, self.line); // [value]
322                let idx =
323                    self.string_constant("non-null assertion failed: value was nil (unwrap_nil)");
324                self.chunk.emit_u16(Op::Constant, idx, self.line);
325                self.chunk.emit(Op::Throw, self.line);
326                // present path: drop the bool, leaving the value.
327                self.chunk.patch_jump(present_jump);
328                self.chunk.emit(Op::Pop, self.line); // [value]
329            }
330            Node::Ternary {
331                condition,
332                true_expr,
333                false_expr,
334            } => {
335                self.compile_node(condition)?;
336                let else_jump = self.chunk.emit_jump(Op::JumpIfFalse, self.line);
337                self.chunk.emit(Op::Pop, self.line);
338                self.compile_node(true_expr)?;
339                let end_jump = self.chunk.emit_jump(Op::Jump, self.line);
340                self.chunk.patch_jump(else_jump);
341                self.chunk.emit(Op::Pop, self.line);
342                self.compile_node(false_expr)?;
343                self.chunk.patch_jump(end_jump);
344            }
345            Node::FunctionCall { name, args, .. } => {
346                self.compile_function_call(name, args)?;
347            }
348            Node::MethodCall {
349                object,
350                method,
351                args,
352            } => {
353                self.compile_method_call(object, method, args)?;
354            }
355            Node::OptionalMethodCall {
356                object,
357                method,
358                args,
359            } => {
360                self.compile_node(object)?;
361                for arg in args {
362                    self.compile_node(arg)?;
363                }
364                let name_idx = self.string_constant(method);
365                self.chunk
366                    .emit_method_call_opt(name_idx, args.len() as u8, self.line);
367            }
368            Node::PropertyAccess { object, property } => {
369                self.compile_property_access(object, property)?;
370            }
371            Node::OptionalPropertyAccess { object, property } => {
372                self.compile_node(object)?;
373                let idx = self.string_constant(property);
374                self.chunk.emit_u16(Op::GetPropertyOpt, idx, self.line);
375            }
376            Node::SubscriptAccess { object, index } => {
377                self.compile_node(object)?;
378                self.compile_node(index)?;
379                self.chunk.emit(Op::Subscript, self.line);
380            }
381            Node::OptionalSubscriptAccess { object, index } => {
382                self.compile_node(object)?;
383                self.compile_node(index)?;
384                self.chunk.emit(Op::SubscriptOpt, self.line);
385            }
386            Node::SliceAccess { object, start, end } => {
387                self.compile_node(object)?;
388                if let Some(s) = start {
389                    self.compile_node(s)?;
390                } else {
391                    self.chunk.emit(Op::Nil, self.line);
392                }
393                if let Some(e) = end {
394                    self.compile_node(e)?;
395                } else {
396                    self.chunk.emit(Op::Nil, self.line);
397                }
398                self.chunk.emit(Op::Slice, self.line);
399            }
400            Node::IfElse {
401                condition,
402                then_body,
403                else_body,
404            } => {
405                self.compile_if_else(condition, then_body, else_body)?;
406            }
407            Node::WhileLoop { condition, body } => {
408                self.compile_while_loop(condition, body)?;
409            }
410            Node::ForIn {
411                pattern,
412                iterable,
413                body,
414            } => {
415                self.compile_for_in(pattern, iterable, body)?;
416            }
417            Node::ReturnStmt { value } => {
418                self.compile_return_stmt(value)?;
419            }
420            Node::BreakStmt => {
421                self.compile_break_stmt()?;
422            }
423            Node::ContinueStmt => {
424                self.compile_continue_stmt()?;
425            }
426            Node::ListLiteral(elements) => {
427                self.compile_list_literal(elements)?;
428            }
429            Node::DictLiteral(entries) => {
430                self.compile_dict_literal(entries)?;
431            }
432            Node::InterpolatedString(segments) => {
433                self.compile_interpolated_string(segments)?;
434            }
435            Node::FnDecl {
436                name,
437                type_params,
438                params,
439                body,
440                is_stream,
441                ..
442            } => {
443                self.compile_fn_decl(name, type_params, params, body, *is_stream)?;
444            }
445            Node::ToolDecl {
446                name,
447                description,
448                params,
449                return_type,
450                body,
451                ..
452            } => {
453                self.compile_tool_decl(name, description, params, return_type, body)?;
454            }
455            Node::SkillDecl { name, fields, .. } => {
456                self.compile_skill_decl(name, fields)?;
457            }
458            Node::EvalPackDecl {
459                binding_name,
460                pack_id,
461                fields,
462                body,
463                summarize,
464                ..
465            } => {
466                self.compile_eval_pack_decl(binding_name, pack_id, fields, body, summarize, true)?;
467            }
468            Node::Closure { params, body, .. } => {
469                self.compile_closure(params, body)?;
470            }
471            Node::ThrowStmt { value } => {
472                self.compile_throw_stmt(value)?;
473            }
474            Node::MatchExpr { value, arms } => {
475                self.compile_match_expr(value, arms)?;
476            }
477            Node::RangeExpr {
478                start,
479                end,
480                inclusive,
481            } => {
482                let name_idx = self.string_constant("__range__");
483                self.chunk.emit_u16(Op::Constant, name_idx, self.line);
484                self.compile_node(start)?;
485                self.compile_node(end)?;
486                if *inclusive {
487                    self.chunk.emit(Op::True, self.line);
488                } else {
489                    self.chunk.emit(Op::False, self.line);
490                }
491                self.chunk.emit_u8(Op::Call, 3, self.line);
492            }
493            Node::GuardStmt {
494                condition,
495                else_body,
496            } => {
497                self.compile_guard_stmt(condition, else_body)?;
498            }
499            Node::RequireStmt { condition, message } => {
500                self.compile_node(condition)?;
501                let ok_jump = self.chunk.emit_jump(Op::JumpIfTrue, self.line);
502                self.chunk.emit(Op::Pop, self.line);
503                if let Some(message) = message {
504                    self.compile_node(message)?;
505                } else {
506                    let idx = self.string_constant("require condition failed");
507                    self.chunk.emit_u16(Op::Constant, idx, self.line);
508                }
509                self.chunk.emit(Op::Throw, self.line);
510                self.chunk.patch_jump(ok_jump);
511                self.chunk.emit(Op::Pop, self.line);
512            }
513            Node::Block(stmts) => {
514                self.compile_scoped_block(stmts)?;
515            }
516            Node::DeadlineBlock { duration, body } => {
517                self.compile_node(duration)?;
518                self.chunk.emit(Op::DeadlineSetup, self.line);
519                self.compile_scoped_block(body)?;
520                self.chunk.emit(Op::DeadlineEnd, self.line);
521            }
522            Node::MutexBlock { key, body } => {
523                self.begin_scope();
524                let finally_floor = self.finally_bodies.len();
525                match key {
526                    // `mutex(resource) { ... }`: evaluate the resource and key
527                    // the lock on its structural value at runtime.
528                    Some(key_expr) => {
529                        self.compile_node(key_expr)?;
530                        self.chunk.emit(Op::SyncMutexEnterKeyed, self.line);
531                    }
532                    // `mutex { ... }`: key on the lexical call-site (computed in
533                    // the VM from the chunk + instruction pointer) so distinct
534                    // blocks don't contend on one global lock.
535                    None => {
536                        self.chunk.emit(Op::SyncMutexEnter, self.line);
537                    }
538                }
539                for sn in body {
540                    self.compile_discarded_stmt(sn)?;
541                }
542                self.drain_finallys_to_floor(finally_floor)?;
543                self.chunk.emit(Op::Nil, self.line);
544                self.end_scope();
545            }
546            Node::ScopeBlock { body } => {
547                // Structured-concurrency nursery. `TaskScopeEnter` pushes a task
548                // scope; tasks spawned inside register to it. `TaskScopeExit`
549                // joins them (propagating the first error, cancelling the rest).
550                // On `throw`/early exit the scope is unwound and its tasks
551                // cancelled by the frame/handler teardown, mirroring
552                // `held_sync_guards`.
553                self.begin_scope();
554                let finally_floor = self.finally_bodies.len();
555                self.chunk.emit(Op::TaskScopeEnter, self.line);
556                for sn in body {
557                    self.compile_discarded_stmt(sn)?;
558                }
559                self.drain_finallys_to_floor(finally_floor)?;
560                self.chunk.emit(Op::TaskScopeExit, self.line);
561                self.chunk.emit(Op::Nil, self.line);
562                self.end_scope();
563            }
564            Node::DeferStmt { body } => {
565                // Register the body to run on return/throw/scope-exit. The
566                // statement emits no bytecode of its own — the deferred body
567                // is inlined later by the finally-draining machinery — so it
568                // leaves the operand stack untouched, matching
569                // `produces_value` == false. Emitting a `Nil` here instead
570                // leaked an unpopped slot per execution, which in a loop body
571                // grew the operand stack without bound (surfaced by the
572                // #2622 balance assertion).
573                self.finally_bodies
574                    .push(FinallyEntry::Finally(body.clone()));
575            }
576            Node::YieldExpr { value } => {
577                if let Some(val) = value {
578                    self.compile_node(val)?;
579                } else {
580                    self.chunk.emit(Op::Nil, self.line);
581                }
582                self.chunk.emit(Op::Yield, self.line);
583            }
584            Node::EmitExpr { value } => {
585                self.compile_node(value)?;
586                self.chunk.emit(Op::Yield, self.line);
587            }
588            Node::EnumConstruct {
589                enum_name,
590                variant,
591                args,
592            } => {
593                self.compile_enum_construct(enum_name, variant, args)?;
594            }
595            Node::StructConstruct {
596                struct_name,
597                fields,
598            } => {
599                self.compile_struct_construct(struct_name, fields)?;
600            }
601            Node::ImportDecl { path, .. } => {
602                let idx = self.string_constant(path);
603                self.chunk.emit_u16(Op::Import, idx, self.line);
604            }
605            Node::SelectiveImport { names, path, .. } => {
606                let path_idx = self.string_constant(path);
607                let names_str = names.join(",");
608                let names_idx = self.owned_string_constant(names_str);
609                self.chunk
610                    .emit_u16(Op::SelectiveImport, path_idx, self.line);
611                let hi = (names_idx >> 8) as u8;
612                let lo = names_idx as u8;
613                self.chunk.code.push(hi);
614                self.chunk.code.push(lo);
615                self.chunk.lines.push(self.line);
616                self.chunk.columns.push(self.column);
617                self.chunk.lines.push(self.line);
618                self.chunk.columns.push(self.column);
619            }
620            Node::TryOperator { operand } => {
621                self.compile_node(operand)?;
622                self.chunk.emit(Op::TryUnwrap, self.line);
623            }
624            // `try* EXPR`: evaluate EXPR; on throw, run pending finally
625            // blocks up to the innermost catch barrier and rethrow the
626            // original value. On success, leave EXPR's value on the stack.
627            //
628            // Per the issue-#26 desugaring:
629            //   { let _r = try { EXPR }
630            //     guard is_ok(_r) else { throw unwrap_err(_r) }
631            //     unwrap(_r) }
632            //
633            // The bytecode realizes this directly: install a try handler
634            // around EXPR so a throw lands in our catch path, where we
635            // pre-run pending finallys and re-emit `Throw`. Skipping the
636            // intermediate Result.Ok/Err wrapping that `TryExpr` does
637            // keeps the success path a no-op (operand value passes through
638            // as-is).
639            Node::TryStar { operand } => {
640                self.compile_try_star(operand)?;
641            }
642            Node::ImplBlock { type_name, methods } => {
643                self.compile_impl_block(type_name, methods)?;
644            }
645            Node::StructDecl { name, fields, .. } => {
646                self.compile_struct_decl(name, fields)?;
647            }
648            // Metadata-only declarations: enum names, struct/interface
649            // layouts, and type aliases are pre-scanned, so they emit no
650            // bytecode and leave the operand stack untouched. Type-alias names
651            // in expression position lower directly to schema constants in the
652            // `Identifier` arm above; eagerly binding every alias at top level
653            // bloats large module init chunks past the VM's 64 KiB jump limit.
654            // `produces_value` classifies them as non-value-producing to match;
655            // contexts that require a block to yield a value (last statement of
656            // a block, match-arm body) emit their own `Nil` placeholder.
657            // Emitting one here instead left an unpopped `Nil` on the stack in
658            // every value-discarding context (`compile_top_level_declarations`
659            // pops nothing) — a latent imbalance surfaced by the #2622 balance
660            // assertion.
661            Node::Pipeline { .. }
662            | Node::OverrideDecl { .. }
663            | Node::TypeDecl { .. }
664            | Node::EnumDecl { .. }
665            | Node::InterfaceDecl { .. } => {}
666            Node::TryCatch {
667                has_catch: _,
668                body,
669                error_var,
670                error_type,
671                catch_body,
672                finally_body,
673            } => {
674                self.compile_try_catch(body, error_var, error_type, catch_body, finally_body)?;
675            }
676            Node::TryExpr { body } => {
677                self.compile_try_expr(body)?;
678            }
679            Node::Retry { count, body } => {
680                self.compile_retry(count, body)?;
681            }
682            Node::CostRoute { options, body } => {
683                self.compile_cost_route(options, body)?;
684            }
685            Node::Parallel {
686                mode,
687                expr,
688                variable,
689                body,
690                options,
691            } => {
692                self.compile_parallel(mode, expr, variable, body, options)?;
693            }
694            Node::SpawnExpr { body } => {
695                self.compile_spawn_expr(body)?;
696            }
697            Node::HitlExpr { kind, args } => {
698                self.compile_hitl_expr(*kind, args)?;
699            }
700            Node::SelectExpr {
701                cases,
702                timeout,
703                default_body,
704            } => {
705                self.compile_select_expr(cases, timeout, default_body)?;
706            }
707            Node::Spread(_) => {
708                return Err(CompileError {
709                    message: "spread (...) can only be used inside list literals, dict literals, or function call arguments".into(),
710                    line: self.line,
711                });
712            }
713            Node::AttributedDecl { attributes, inner } => {
714                self.compile_attributed_decl(attributes, inner)?;
715            }
716            Node::OrPattern(_) => {
717                return Err(CompileError {
718                    message: "or-pattern (|) can only appear as a match arm pattern".into(),
719                    line: self.line,
720                });
721            }
722        }
723        Ok(())
724    }
725}