1mod expr_checker;
2mod item_checker;
3mod stmt_checker;
4mod type_env;
5use crate::modules::{LoadedModule, ModuleImports};
6use crate::{
7 ast::*,
8 config::LustConfig,
9 error::{LustError, Result},
10};
11pub(super) use alloc::{
12 boxed::Box,
13 format,
14 string::{String, ToString},
15 vec,
16 vec::Vec,
17};
18use core::mem;
19use hashbrown::{HashMap, HashSet};
20pub use type_env::FunctionSignature;
21pub use type_env::TypeEnv;
22pub struct TypeChecker {
23 env: TypeEnv,
24 current_function_return_type: Option<Type>,
25 in_loop: bool,
26 pending_generic_instances: Option<HashMap<String, Type>>,
27 expected_lambda_signature: Option<(Vec<Type>, Option<Type>)>,
28 current_trait_bounds: HashMap<String, Vec<String>>,
29 current_module: Option<String>,
30 imports_by_module: HashMap<String, ModuleImports>,
31 expr_types_by_module: HashMap<String, HashMap<Span, Type>>,
32 variable_types_by_module: HashMap<String, HashMap<Span, Type>>,
33 short_circuit_info: HashMap<String, HashMap<Span, ShortCircuitInfo>>,
34}
35
36pub struct TypeCollection {
37 pub expr_types: HashMap<String, HashMap<Span, Type>>,
38 pub variable_types: HashMap<String, HashMap<Span, Type>>,
39}
40
41#[derive(Clone, Debug)]
42struct ShortCircuitInfo {
43 truthy: Option<Type>,
44 falsy: Option<Type>,
45 option_inner: Option<Type>,
46}
47
48impl TypeChecker {
49 pub fn new() -> Self {
50 Self::with_config(&LustConfig::default())
51 }
52
53 pub fn with_config(config: &LustConfig) -> Self {
54 Self {
55 env: TypeEnv::with_config(config),
56 current_function_return_type: None,
57 in_loop: false,
58 pending_generic_instances: None,
59 expected_lambda_signature: None,
60 current_trait_bounds: HashMap::new(),
61 current_module: None,
62 imports_by_module: HashMap::new(),
63 expr_types_by_module: HashMap::new(),
64 variable_types_by_module: HashMap::new(),
65 short_circuit_info: HashMap::new(),
66 }
67 }
68
69 fn dummy_span() -> Span {
70 Span::new(0, 0, 0, 0)
71 }
72
73 pub fn check_module(&mut self, items: &[Item]) -> Result<()> {
74 for item in items {
75 self.register_type_definition(item)?;
76 }
77
78 self.validate_struct_cycles()?;
79 self.env.push_scope();
80 self.register_module_init_locals(items)?;
81 for item in items {
82 self.check_item(item)?;
83 }
84
85 self.env.pop_scope();
86 Ok(())
87 }
88
89 pub fn check_program(&mut self, modules: &[LoadedModule]) -> Result<()> {
90 for m in modules {
91 self.current_module = Some(m.path.clone());
92 for item in &m.items {
93 self.register_type_definition(item)?;
94 }
95 }
96
97 self.validate_struct_cycles()?;
98 for m in modules {
99 self.current_module = Some(m.path.clone());
100 self.env.push_scope();
101 self.register_module_init_locals(&m.items)?;
102 for item in &m.items {
103 self.check_item(item)?;
104 }
105
106 self.env.pop_scope();
107 }
108
109 self.current_module = None;
110 Ok(())
111 }
112
113 fn validate_struct_cycles(&self) -> Result<()> {
114 use hashbrown::{HashMap, HashSet};
115 let struct_defs = self.env.struct_definitions();
116 if struct_defs.is_empty() {
117 return Ok(());
118 }
119
120 let mut simple_to_full: HashMap<String, Vec<String>> = HashMap::new();
121 for name in struct_defs.keys() {
122 let simple = name.rsplit('.').next().unwrap_or(name).to_string();
123 simple_to_full.entry(simple).or_default().push(name.clone());
124 }
125
126 let mut struct_has_weak: HashMap<String, bool> = HashMap::new();
127 for (name, def) in &struct_defs {
128 let has_weak = def
129 .fields
130 .iter()
131 .any(|field| matches!(field.ownership, FieldOwnership::Weak));
132 struct_has_weak.insert(name.clone(), has_weak);
133 }
134
135 let mut graph: HashMap<String, Vec<String>> = HashMap::new();
136 for (name, def) in &struct_defs {
137 let module_prefix = name.rsplit_once('.').map(|(module, _)| module.to_string());
138 let mut edges: HashSet<String> = HashSet::new();
139 for field in &def.fields {
140 if matches!(field.ownership, FieldOwnership::Weak) {
141 let target = field.weak_target.as_ref().ok_or_else(|| {
142 self.type_error(format!(
143 "Field '{}.{}' is marked as 'ref' but has no target type",
144 name, field.name
145 ))
146 })?;
147 let target_name = if let TypeKind::Named(inner) = &target.kind {
148 inner
149 } else {
150 return Err(self.type_error(format!(
151 "Field '{}.{}' uses 'ref' but only struct types are supported",
152 name, field.name
153 )));
154 };
155 let resolved = self.resolve_struct_name_for_cycle(
156 target_name.as_str(),
157 module_prefix.as_deref(),
158 &struct_defs,
159 &simple_to_full,
160 );
161 if resolved.is_none() {
162 return Err(self.type_error(format!(
163 "Field '{}.{}' uses 'ref' but '{}' is not a known struct type",
164 name, field.name, target_name
165 )));
166 }
167
168 continue;
169 }
170
171 self.collect_strong_struct_targets(
172 &field.ty,
173 module_prefix.as_deref(),
174 &struct_defs,
175 &simple_to_full,
176 &mut edges,
177 );
178 }
179
180 graph.insert(name.clone(), edges.into_iter().collect());
181 }
182
183 fn dfs(
184 node: &str,
185 graph: &HashMap<String, Vec<String>>,
186 visited: &mut HashSet<String>,
187 on_stack: &mut HashSet<String>,
188 stack: &mut Vec<String>,
189 ) -> Option<Vec<String>> {
190 visited.insert(node.to_string());
191 on_stack.insert(node.to_string());
192 stack.push(node.to_string());
193 if let Some(neighbors) = graph.get(node) {
194 for neighbor in neighbors {
195 if !visited.contains(neighbor) {
196 if let Some(cycle) = dfs(neighbor, graph, visited, on_stack, stack) {
197 return Some(cycle);
198 }
199 } else if on_stack.contains(neighbor) {
200 if let Some(pos) = stack.iter().position(|n| n == neighbor) {
201 let mut cycle = stack[pos..].to_vec();
202 cycle.push(neighbor.clone());
203 return Some(cycle);
204 }
205 }
206 }
207 }
208
209 stack.pop();
210 on_stack.remove(node);
211 None
212 }
213
214 let mut visited: HashSet<String> = HashSet::new();
215 let mut on_stack: HashSet<String> = HashSet::new();
216 let mut stack: Vec<String> = Vec::new();
217 for name in struct_defs.keys() {
218 if !visited.contains(name) {
219 if let Some(cycle) = dfs(name, &graph, &mut visited, &mut on_stack, &mut stack) {
220 let contains_weak = cycle
221 .iter()
222 .any(|node| struct_has_weak.get(node).copied().unwrap_or(false));
223 if contains_weak {
224 continue;
225 }
226
227 let description = cycle.join(" -> ");
228 break;
229 }
234 }
235 }
236
237 Ok(())
238 }
239
240 fn collect_strong_struct_targets(
241 &self,
242 ty: &Type,
243 parent_module: Option<&str>,
244 struct_defs: &HashMap<String, StructDef>,
245 simple_to_full: &HashMap<String, Vec<String>>,
246 out: &mut HashSet<String>,
247 ) {
248 match &ty.kind {
249 TypeKind::Named(name) => {
250 if let Some(resolved) = self.resolve_struct_name_for_cycle(
251 name,
252 parent_module,
253 struct_defs,
254 simple_to_full,
255 ) {
256 out.insert(resolved);
257 }
258 }
259
260 TypeKind::Array(inner)
261 | TypeKind::Ref(inner)
262 | TypeKind::MutRef(inner)
263 | TypeKind::Option(inner) => {
264 self.collect_strong_struct_targets(
265 inner,
266 parent_module,
267 struct_defs,
268 simple_to_full,
269 out,
270 );
271 }
272
273 TypeKind::Map(key, value) => {
274 self.collect_strong_struct_targets(
275 key,
276 parent_module,
277 struct_defs,
278 simple_to_full,
279 out,
280 );
281 self.collect_strong_struct_targets(
282 value,
283 parent_module,
284 struct_defs,
285 simple_to_full,
286 out,
287 );
288 }
289
290 TypeKind::Tuple(elements) | TypeKind::Union(elements) => {
291 for element in elements {
292 self.collect_strong_struct_targets(
293 element,
294 parent_module,
295 struct_defs,
296 simple_to_full,
297 out,
298 );
299 }
300 }
301
302 TypeKind::Result(ok, err) => {
303 self.collect_strong_struct_targets(
304 ok,
305 parent_module,
306 struct_defs,
307 simple_to_full,
308 out,
309 );
310 self.collect_strong_struct_targets(
311 err,
312 parent_module,
313 struct_defs,
314 simple_to_full,
315 out,
316 );
317 }
318
319 TypeKind::GenericInstance { type_args, .. } => {
320 for arg in type_args {
321 self.collect_strong_struct_targets(
322 arg,
323 parent_module,
324 struct_defs,
325 simple_to_full,
326 out,
327 );
328 }
329 }
330
331 _ => {}
332 }
333 }
334
335 fn resolve_struct_name_for_cycle(
336 &self,
337 name: &str,
338 parent_module: Option<&str>,
339 struct_defs: &HashMap<String, StructDef>,
340 simple_to_full: &HashMap<String, Vec<String>>,
341 ) -> Option<String> {
342 if struct_defs.contains_key(name) {
343 return Some(name.to_string());
344 }
345
346 if name.contains('.') {
347 return None;
348 }
349
350 if let Some(candidates) = simple_to_full.get(name) {
351 if candidates.len() == 1 {
352 return Some(candidates[0].clone());
353 }
354
355 if let Some(module) = parent_module {
356 for candidate in candidates {
357 if let Some((candidate_module, _)) = candidate.rsplit_once('.') {
358 if candidate_module == module {
359 return Some(candidate.clone());
360 }
361 }
362 }
363 }
364 }
365
366 None
367 }
368
369 pub fn set_imports_by_module(&mut self, map: HashMap<String, ModuleImports>) {
370 self.imports_by_module = map;
371 }
372
373 pub fn take_type_info(&mut self) -> TypeCollection {
374 TypeCollection {
375 expr_types: mem::take(&mut self.expr_types_by_module),
376 variable_types: mem::take(&mut self.variable_types_by_module),
377 }
378 }
379
380 pub fn take_option_coercions(&mut self) -> HashMap<String, HashSet<Span>> {
381 let mut result: HashMap<String, HashSet<Span>> = HashMap::new();
382 let info = mem::take(&mut self.short_circuit_info);
383 for (module, entries) in info {
384 let mut spans: HashSet<Span> = HashSet::new();
385 for (span, entry) in entries {
386 if entry.option_inner.is_some() {
387 spans.insert(span);
388 }
389 }
390 if !spans.is_empty() {
391 result.insert(module, spans);
392 }
393 }
394
395 result
396 }
397
398 pub fn function_signatures(&self) -> HashMap<String, type_env::FunctionSignature> {
399 self.env.function_signatures()
400 }
401
402 pub fn struct_definitions(&self) -> HashMap<String, StructDef> {
403 self.env.struct_definitions()
404 }
405
406 pub fn enum_definitions(&self) -> HashMap<String, EnumDef> {
407 self.env.enum_definitions()
408 }
409
410 fn register_module_init_locals(&mut self, items: &[Item]) -> Result<()> {
411 let module = match &self.current_module {
412 Some(m) => m.clone(),
413 None => return Ok(()),
414 };
415 let init_name = format!("__init@{}", module);
416 for item in items {
417 if let ItemKind::Function(func) = &item.kind {
418 if func.name == init_name {
419 for stmt in &func.body {
420 if let StmtKind::Local {
421 bindings,
422 ref mutable,
423 initializer,
424 } = &stmt.kind
425 {
426 self.check_local_stmt(
427 bindings.as_slice(),
428 *mutable,
429 initializer.as_ref().map(|values| values.as_slice()),
430 )?;
431 }
432 }
433 }
434 }
435 }
436
437 Ok(())
438 }
439
440 pub fn resolve_function_key(&self, name: &str) -> String {
441 if name.contains('.') || name.contains(':') {
442 return name.to_string();
443 }
444
445 if let Some(module) = &self.current_module {
446 if let Some(imports) = self.imports_by_module.get(module) {
447 if let Some(fq) = imports.function_aliases.get(name) {
448 return fq.clone();
449 }
450 }
451
452 let qualified = format!("{}.{}", module, name);
453 if self.env.lookup_function(&qualified).is_some() {
454 return qualified;
455 }
456
457 if self.env.lookup_function(name).is_some() {
458 return name.to_string();
459 }
460
461 return qualified;
462 }
463
464 name.to_string()
465 }
466
467 pub fn resolve_module_alias(&self, alias: &str) -> Option<String> {
468 if let Some(module) = &self.current_module {
469 if let Some(imports) = self.imports_by_module.get(module) {
470 if let Some(m) = imports.module_aliases.get(alias) {
471 return Some(m.clone());
472 }
473 }
474 }
475
476 None
477 }
478
479 pub fn register_external_struct(&mut self, mut def: StructDef) -> Result<()> {
480 def.name = self.resolve_type_key(&def.name);
481 for field in &mut def.fields {
482 field.ty = self.canonicalize_type(&field.ty);
483 if let Some(target) = &field.weak_target {
484 field.weak_target = Some(self.canonicalize_type(target));
485 }
486 }
487 self.env.register_struct(&def)
488 }
489
490 pub fn register_external_enum(&mut self, mut def: EnumDef) -> Result<()> {
491 def.name = self.resolve_type_key(&def.name);
492 for variant in &mut def.variants {
493 if let Some(fields) = &mut variant.fields {
494 for field in fields {
495 *field = self.canonicalize_type(field);
496 }
497 }
498 }
499 self.env.register_enum(&def)
500 }
501
502 pub fn register_external_trait(&mut self, mut def: TraitDef) -> Result<()> {
503 def.name = self.resolve_type_key(&def.name);
504 for method in &mut def.methods {
505 for param in &mut method.params {
506 param.ty = self.canonicalize_type(¶m.ty);
507 }
508 if let Some(ret) = method.return_type.clone() {
509 method.return_type = Some(self.canonicalize_type(&ret));
510 }
511 }
512 self.env.register_trait(&def)
513 }
514
515 pub fn register_external_function(
516 &mut self,
517 (name, mut signature): (String, FunctionSignature),
518 ) -> Result<()> {
519 signature.params = signature
520 .params
521 .into_iter()
522 .map(|ty| self.canonicalize_type(&ty))
523 .collect();
524 signature.return_type = self.canonicalize_type(&signature.return_type);
525 let canonical = self.resolve_type_key(&name);
526 self.env.register_or_update_function(canonical, signature)
527 }
528
529 pub fn register_external_impl(&mut self, mut impl_block: ImplBlock) -> Result<()> {
530 impl_block.target_type = self.canonicalize_type(&impl_block.target_type);
531 if let Some(trait_name) = &impl_block.trait_name {
532 impl_block.trait_name = Some(self.resolve_type_key(trait_name));
533 }
534 for method in &mut impl_block.methods {
535 for param in &mut method.params {
536 param.ty = self.canonicalize_type(¶m.ty);
537 }
538 if let Some(ret) = method.return_type.clone() {
539 method.return_type = Some(self.canonicalize_type(&ret));
540 }
541 }
542
543 let type_name = match &impl_block.target_type.kind {
544 TypeKind::Named(name) => self.resolve_type_key(name),
545 TypeKind::GenericInstance { name, .. } => self.resolve_type_key(name),
546 _ => {
547 return Err(self.type_error(
548 "Impl target must be a named type when registering from Rust".to_string(),
549 ))
550 }
551 };
552
553 self.env.register_impl(&impl_block);
554 for method in &impl_block.methods {
555 let params: Vec<Type> = method.params.iter().map(|p| p.ty.clone()).collect();
556 let return_type = method
557 .return_type
558 .clone()
559 .unwrap_or(Type::new(TypeKind::Unit, Span::dummy()));
560 let has_self = method.params.iter().any(|p| p.is_self);
561 let canonical_name = if method.name.contains(':') || method.name.contains('.') {
562 self.resolve_type_key(&method.name)
563 } else if has_self {
564 format!("{}:{}", type_name, method.name)
565 } else {
566 format!("{}.{}", type_name, method.name)
567 };
568 #[cfg(debug_assertions)]
569 eprintln!(
570 "register_external_impl canonical method {} (has_self={})",
571 canonical_name, has_self
572 );
573 let signature = FunctionSignature {
574 params,
575 return_type,
576 is_method: has_self,
577 };
578 self.env
579 .register_or_update_function(canonical_name, signature)?;
580 }
581
582 Ok(())
583 }
584
585 pub fn resolve_type_key(&self, name: &str) -> String {
586 if let Some((head, tail)) = name.split_once('.') {
587 if let Some(module) = &self.current_module {
588 if let Some(imports) = self.imports_by_module.get(module) {
589 if let Some(real_module) = imports.module_aliases.get(head) {
590 if tail.is_empty() {
591 return real_module.clone();
592 } else {
593 return format!("{}.{}", real_module, tail);
594 }
595 }
596 }
597 }
598
599 return name.to_string();
600 }
601
602 if self.env.lookup_struct(name).is_some()
603 || self.env.lookup_enum(name).is_some()
604 || self.env.lookup_trait(name).is_some()
605 {
606 return name.to_string();
607 }
608
609 if self.env.is_builtin_type(name) {
610 return name.to_string();
611 }
612
613 if let Some(module) = &self.current_module {
614 if let Some(imports) = self.imports_by_module.get(module) {
615 if let Some(fq) = imports.type_aliases.get(name) {
616 return fq.clone();
617 }
618 }
619
620 return format!("{}.{}", module, name);
621 }
622
623 name.to_string()
624 }
625
626 fn register_type_definition(&mut self, item: &Item) -> Result<()> {
627 match &item.kind {
628 ItemKind::Struct(s) => {
629 let mut s2 = s.clone();
630 if let Some(module) = &self.current_module {
631 if !s2.name.contains('.') {
632 s2.name = format!("{}.{}", module, s2.name);
633 }
634 }
635
636 self.env.register_struct(&s2)?;
637 }
638
639 ItemKind::Enum(e) => {
640 let mut e2 = e.clone();
641 if let Some(module) = &self.current_module {
642 if !e2.name.contains('.') {
643 e2.name = format!("{}.{}", module, e2.name);
644 }
645 }
646
647 self.env.register_enum(&e2)?;
648 }
649
650 ItemKind::Trait(t) => {
651 let mut t2 = t.clone();
652 if let Some(module) = &self.current_module {
653 if !t2.name.contains('.') {
654 t2.name = format!("{}.{}", module, t2.name);
655 }
656 }
657
658 self.env.register_trait(&t2)?;
659 }
660
661 ItemKind::TypeAlias {
662 name,
663 type_params,
664 target,
665 } => {
666 let qname = if let Some(module) = &self.current_module {
667 if name.contains('.') {
668 name.clone()
669 } else {
670 format!("{}.{}", module, name)
671 }
672 } else {
673 name.clone()
674 };
675 self.env
676 .register_type_alias(qname, type_params.clone(), target.clone())?;
677 }
678
679 _ => {}
680 }
681
682 Ok(())
683 }
684
685 fn type_error(&self, message: String) -> LustError {
686 LustError::TypeError { message }
687 }
688
689 fn type_error_at(&self, message: String, span: Span) -> LustError {
690 if span.start_line > 0 {
691 LustError::TypeErrorWithSpan {
692 message,
693 line: span.start_line,
694 column: span.start_col,
695 module: self.current_module.clone(),
696 }
697 } else {
698 LustError::TypeError { message }
699 }
700 }
701
702 fn types_equal(&self, t1: &Type, t2: &Type) -> bool {
703 t1.kind == t2.kind
704 }
705
706 pub fn canonicalize_type(&self, ty: &Type) -> Type {
707 use crate::ast::TypeKind as TK;
708 match &ty.kind {
709 TK::Named(name) => Type::new(TK::Named(self.resolve_type_key(name)), ty.span),
710 TK::Array(inner) => {
711 Type::new(TK::Array(Box::new(self.canonicalize_type(inner))), ty.span)
712 }
713
714 TK::Tuple(elements) => Type::new(
715 TK::Tuple(elements.iter().map(|t| self.canonicalize_type(t)).collect()),
716 ty.span,
717 ),
718 TK::Option(inner) => {
719 Type::new(TK::Option(Box::new(self.canonicalize_type(inner))), ty.span)
720 }
721
722 TK::Result(ok, err) => Type::new(
723 TK::Result(
724 Box::new(self.canonicalize_type(ok)),
725 Box::new(self.canonicalize_type(err)),
726 ),
727 ty.span,
728 ),
729 TK::Map(k, v) => Type::new(
730 TK::Map(
731 Box::new(self.canonicalize_type(k)),
732 Box::new(self.canonicalize_type(v)),
733 ),
734 ty.span,
735 ),
736 TK::Ref(inner) => Type::new(TK::Ref(Box::new(self.canonicalize_type(inner))), ty.span),
737 TK::MutRef(inner) => {
738 Type::new(TK::MutRef(Box::new(self.canonicalize_type(inner))), ty.span)
739 }
740
741 TK::Pointer { mutable, pointee } => Type::new(
742 TK::Pointer {
743 mutable: *mutable,
744 pointee: Box::new(self.canonicalize_type(pointee)),
745 },
746 ty.span,
747 ),
748 _ => ty.clone(),
749 }
750 }
751
752 fn unify(&self, expected: &Type, actual: &Type) -> Result<()> {
753 let span = if actual.span.start_line > 0 {
754 Some(actual.span)
755 } else if expected.span.start_line > 0 {
756 Some(expected.span)
757 } else {
758 None
759 };
760 self.unify_at(expected, actual, span)
761 }
762
763 fn unify_at(&self, expected: &Type, actual: &Type, span: Option<Span>) -> Result<()> {
764 if matches!(expected.kind, TypeKind::Unknown) || matches!(actual.kind, TypeKind::Unknown) {
765 return Ok(());
766 }
767
768 if matches!(expected.kind, TypeKind::Infer) || matches!(actual.kind, TypeKind::Infer) {
769 return Ok(());
770 }
771
772 match (&expected.kind, &actual.kind) {
773 (TypeKind::Union(expected_types), TypeKind::Union(actual_types)) => {
774 if expected_types.len() != actual_types.len() {
775 return Err(self.type_error(format!(
776 "Union types have different number of members: expected {}, got {}",
777 expected_types.len(),
778 actual_types.len()
779 )));
780 }
781
782 for exp_type in expected_types {
783 let mut found = false;
784 for act_type in actual_types {
785 if self.types_equal(exp_type, act_type) {
786 found = true;
787 break;
788 }
789 }
790
791 if !found {
792 return Err(match span {
793 Some(s) => self.type_error_at(
794 format!(
795 "Union type member '{}' not found in actual union",
796 exp_type
797 ),
798 s,
799 ),
800 None => self.type_error(format!(
801 "Union type member '{}' not found in actual union",
802 exp_type
803 )),
804 });
805 }
806 }
807
808 return Ok(());
809 }
810
811 (TypeKind::Union(expected_types), _) => {
812 for union_member in expected_types {
813 if self.unify(union_member, actual).is_ok() {
814 return Ok(());
815 }
816 }
817
818 return Err(match span {
819 Some(s) => self.type_error_at(
820 format!("Type '{}' is not compatible with union type", actual),
821 s,
822 ),
823 None => self.type_error(format!(
824 "Type '{}' is not compatible with union type",
825 actual
826 )),
827 });
828 }
829
830 (_, TypeKind::Union(actual_types)) => {
831 for union_member in actual_types {
832 self.unify(expected, union_member)?;
833 }
834
835 return Ok(());
836 }
837
838 _ => {}
839 }
840
841 match (&expected.kind, &actual.kind) {
842 (TypeKind::Tuple(expected_elems), TypeKind::Tuple(actual_elems)) => {
843 if expected_elems.len() != actual_elems.len() {
844 return Err(match span {
845 Some(s) => self.type_error_at(
846 format!(
847 "Tuple length mismatch: expected {} element(s), got {}",
848 expected_elems.len(),
849 actual_elems.len()
850 ),
851 s,
852 ),
853 None => self.type_error(format!(
854 "Tuple length mismatch: expected {} element(s), got {}",
855 expected_elems.len(),
856 actual_elems.len()
857 )),
858 });
859 }
860
861 for (exp_elem, act_elem) in expected_elems.iter().zip(actual_elems.iter()) {
862 self.unify(exp_elem, act_elem)?;
863 }
864
865 return Ok(());
866 }
867
868 (TypeKind::Tuple(_), _) | (_, TypeKind::Tuple(_)) => {
869 return Err(match span {
870 Some(s) => self.type_error_at(
871 format!("Tuple type is not compatible with type '{}'", actual),
872 s,
873 ),
874 None => self.type_error(format!(
875 "Tuple type is not compatible with type '{}'",
876 actual
877 )),
878 })
879 }
880
881 (TypeKind::Named(name), TypeKind::Array(_))
882 | (TypeKind::Array(_), TypeKind::Named(name))
883 if name == "Array" =>
884 {
885 return Ok(());
886 }
887
888 (TypeKind::Array(exp_el), TypeKind::Array(act_el)) => {
889 if matches!(exp_el.kind, TypeKind::Unknown | TypeKind::Infer)
890 || matches!(act_el.kind, TypeKind::Unknown | TypeKind::Infer)
891 {
892 return Ok(());
893 } else {
894 return self.unify(exp_el, act_el);
895 }
896 }
897
898 (TypeKind::Map(exp_key, exp_value), TypeKind::Map(act_key, act_value)) => {
899 self.unify(exp_key, act_key)?;
900 return self.unify(exp_value, act_value);
901 }
902
903 (TypeKind::Named(name), TypeKind::Option(_))
904 | (TypeKind::Option(_), TypeKind::Named(name))
905 if name == "Option" =>
906 {
907 return Ok(());
908 }
909
910 (TypeKind::Option(exp_inner), TypeKind::Option(act_inner)) => {
911 if matches!(exp_inner.kind, TypeKind::Unknown | TypeKind::Infer)
912 || matches!(act_inner.kind, TypeKind::Unknown | TypeKind::Infer)
913 {
914 return Ok(());
915 } else {
916 return self.unify(exp_inner, act_inner);
917 }
918 }
919
920 (TypeKind::Named(name), TypeKind::Result(_, _))
921 | (TypeKind::Result(_, _), TypeKind::Named(name))
922 if name == "Result" =>
923 {
924 return Ok(());
925 }
926
927 (TypeKind::Result(exp_ok, exp_err), TypeKind::Result(act_ok, act_err)) => {
928 if matches!(exp_ok.kind, TypeKind::Unknown | TypeKind::Infer)
929 || matches!(act_ok.kind, TypeKind::Unknown | TypeKind::Infer)
930 {
931 if matches!(exp_err.kind, TypeKind::Unknown | TypeKind::Infer)
932 || matches!(act_err.kind, TypeKind::Unknown | TypeKind::Infer)
933 {
934 return Ok(());
935 } else {
936 return self.unify(exp_err, act_err);
937 }
938 } else {
939 self.unify(exp_ok, act_ok)?;
940 return self.unify(exp_err, act_err);
941 }
942 }
943
944 _ => {}
945 }
946
947 if self.types_equal(expected, actual) {
948 Ok(())
949 } else {
950 Err(match span {
951 Some(s) => self.type_error_at(
952 format!("Type mismatch: expected '{}', got '{}'", expected, actual),
953 s,
954 ),
955 None => self.type_error(format!(
956 "Type mismatch: expected '{}', got '{}'",
957 expected, actual
958 )),
959 })
960 }
961 }
962
963 fn types_compatible(&self, expected: &Type, actual: &Type) -> bool {
964 if matches!(expected.kind, TypeKind::Unknown) || matches!(actual.kind, TypeKind::Unknown) {
965 return true;
966 }
967
968 if matches!(expected.kind, TypeKind::Infer) || matches!(actual.kind, TypeKind::Infer) {
969 return true;
970 }
971
972 match (&expected.kind, &actual.kind) {
973 (TypeKind::Generic(_), TypeKind::Generic(_)) => return true,
974 (TypeKind::Generic(_), _) | (_, TypeKind::Generic(_)) => return true,
975 _ => {}
976 }
977
978 match (&expected.kind, &actual.kind) {
979 (TypeKind::Array(e1), TypeKind::Array(e2)) => {
980 return self.types_compatible(e1, e2);
981 }
982
983 (TypeKind::Named(name), TypeKind::Array(_))
984 | (TypeKind::Array(_), TypeKind::Named(name))
985 if name == "Array" =>
986 {
987 return true;
988 }
989
990 _ => {}
991 }
992
993 match (&expected.kind, &actual.kind) {
994 (TypeKind::Map(k1, v1), TypeKind::Map(k2, v2)) => {
995 return self.types_compatible(k1, k2) && self.types_compatible(v1, v2);
996 }
997
998 _ => {}
999 }
1000
1001 match (&expected.kind, &actual.kind) {
1002 (TypeKind::Option(t1), TypeKind::Option(t2)) => {
1003 return self.types_compatible(t1, t2);
1004 }
1005
1006 (TypeKind::Named(name), TypeKind::Option(_))
1007 | (TypeKind::Option(_), TypeKind::Named(name))
1008 if name == "Option" =>
1009 {
1010 return true;
1011 }
1012
1013 _ => {}
1014 }
1015
1016 match (&expected.kind, &actual.kind) {
1017 (TypeKind::Result(ok1, err1), TypeKind::Result(ok2, err2)) => {
1018 return self.types_compatible(ok1, ok2) && self.types_compatible(err1, err2);
1019 }
1020
1021 (TypeKind::Named(name), TypeKind::Result(_, _))
1022 | (TypeKind::Result(_, _), TypeKind::Named(name))
1023 if name == "Result" =>
1024 {
1025 return true;
1026 }
1027
1028 _ => {}
1029 }
1030
1031 match (&expected.kind, &actual.kind) {
1032 (
1033 TypeKind::Function {
1034 params: p1,
1035 return_type: r1,
1036 },
1037 TypeKind::Function {
1038 params: p2,
1039 return_type: r2,
1040 },
1041 ) => {
1042 if p1.len() != p2.len() {
1043 return false;
1044 }
1045
1046 for (t1, t2) in p1.iter().zip(p2.iter()) {
1047 if !self.types_compatible(t1, t2) {
1048 return false;
1049 }
1050 }
1051
1052 return self.types_compatible(r1, r2);
1053 }
1054
1055 _ => {}
1056 }
1057
1058 self.types_equal(expected, actual)
1059 }
1060
1061 fn unify_with_bounds(&self, expected: &Type, actual: &Type) -> Result<()> {
1062 if let TypeKind::Generic(type_param) = &expected.kind {
1063 if let Some(trait_names) = self.current_trait_bounds.get(type_param) {
1064 for trait_name in trait_names {
1065 if !self.env.type_implements_trait(actual, trait_name) {
1066 return Err(self.type_error(format!(
1067 "Type '{}' does not implement required trait '{}'",
1068 actual, trait_name
1069 )));
1070 }
1071 }
1072
1073 return Ok(());
1074 }
1075
1076 return Ok(());
1077 }
1078
1079 self.unify(expected, actual)
1080 }
1081
1082 fn record_short_circuit_info(&mut self, span: Span, info: &ShortCircuitInfo) {
1083 let truthy = info.truthy.as_ref().map(|ty| self.canonicalize_type(ty));
1084 let falsy = info.falsy.as_ref().map(|ty| self.canonicalize_type(ty));
1085 let option_inner = info
1086 .option_inner
1087 .as_ref()
1088 .map(|ty| self.canonicalize_type(ty));
1089 let module_key = self.current_module_key();
1090 self.short_circuit_info
1091 .entry(module_key)
1092 .or_default()
1093 .insert(
1094 span,
1095 ShortCircuitInfo {
1096 truthy,
1097 falsy,
1098 option_inner,
1099 },
1100 );
1101 }
1102
1103 fn short_circuit_profile(&self, expr: &Expr, ty: &Type) -> ShortCircuitInfo {
1104 let module_key = self
1105 .current_module
1106 .as_ref()
1107 .map(String::as_str)
1108 .unwrap_or("");
1109 if let Some(module_map) = self.short_circuit_info.get(module_key) {
1110 if let Some(info) = module_map.get(&expr.span) {
1111 return info.clone();
1112 }
1113 }
1114
1115 ShortCircuitInfo {
1116 truthy: if self.type_can_be_truthy(ty) {
1117 Some(self.canonicalize_type(ty))
1118 } else {
1119 None
1120 },
1121 falsy: self.extract_falsy_type(ty),
1122 option_inner: None,
1123 }
1124 }
1125
1126 fn current_module_key(&self) -> String {
1127 self.current_module
1128 .as_ref()
1129 .cloned()
1130 .unwrap_or_else(|| "".to_string())
1131 }
1132
1133 fn clear_option_for_span(&mut self, span: Span) {
1134 let module_key = self.current_module_key();
1135 if let Some(module_map) = self.short_circuit_info.get_mut(&module_key) {
1136 if let Some(info) = module_map.get_mut(&span) {
1137 info.option_inner = None;
1138 }
1139 }
1140 }
1141
1142 fn type_can_be_truthy(&self, ty: &Type) -> bool {
1143 match &ty.kind {
1144 TypeKind::Union(members) => {
1145 members.iter().any(|member| self.type_can_be_truthy(member))
1146 }
1147 TypeKind::Bool => true,
1148 TypeKind::Unknown => true,
1149 _ => true,
1150 }
1151 }
1152
1153 fn type_can_be_falsy(&self, ty: &Type) -> bool {
1154 match &ty.kind {
1155 TypeKind::Union(members) => members.iter().any(|member| self.type_can_be_falsy(member)),
1156 TypeKind::Bool => true,
1157 TypeKind::Unknown => true,
1158 TypeKind::Option(_) => true,
1159 _ => false,
1160 }
1161 }
1162
1163 fn extract_falsy_type(&self, ty: &Type) -> Option<Type> {
1164 match &ty.kind {
1165 TypeKind::Bool => Some(Type::new(TypeKind::Bool, ty.span)),
1166 TypeKind::Unknown => Some(Type::new(TypeKind::Unknown, ty.span)),
1167 TypeKind::Option(inner) => Some(Type::new(
1168 TypeKind::Option(Box::new(self.canonicalize_type(inner))),
1169 ty.span,
1170 )),
1171 TypeKind::Union(members) => {
1172 let mut parts = Vec::new();
1173 for member in members {
1174 if let Some(part) = self.extract_falsy_type(member) {
1175 parts.push(part);
1176 }
1177 }
1178 self.merge_optional_types(parts)
1179 }
1180 _ => None,
1181 }
1182 }
1183
1184 fn merge_optional_types(&self, types: Vec<Type>) -> Option<Type> {
1185 if types.is_empty() {
1186 return None;
1187 }
1188
1189 Some(self.make_union_from_types(types))
1190 }
1191
1192 fn make_union_from_types(&self, types: Vec<Type>) -> Type {
1193 let mut flat: Vec<Type> = Vec::new();
1194 for ty in types {
1195 let canonical = self.canonicalize_type(&ty);
1196 match &canonical.kind {
1197 TypeKind::Union(members) => {
1198 for member in members {
1199 self.push_unique_type(&mut flat, member.clone());
1200 }
1201 }
1202 _ => self.push_unique_type(&mut flat, canonical),
1203 }
1204 }
1205
1206 match flat.len() {
1207 0 => Type::new(TypeKind::Unknown, Self::dummy_span()),
1208 1 => flat.into_iter().next().unwrap(),
1209 _ => Type::new(TypeKind::Union(flat), Self::dummy_span()),
1210 }
1211 }
1212
1213 fn push_unique_type(&self, list: &mut Vec<Type>, candidate: Type) {
1214 if !list
1215 .iter()
1216 .any(|existing| self.types_equal(existing, &candidate))
1217 {
1218 list.push(candidate);
1219 }
1220 }
1221
1222 fn combine_truthy_falsy(&self, truthy: Option<Type>, falsy: Option<Type>) -> Type {
1223 match (truthy, falsy) {
1224 (Some(t), Some(f)) => self.make_union_from_types(vec![t, f]),
1225 (Some(t), None) => t,
1226 (None, Some(f)) => f,
1227 (None, None) => Type::new(TypeKind::Unknown, Self::dummy_span()),
1228 }
1229 }
1230
1231 fn is_bool_like(&self, ty: &Type) -> bool {
1232 match &ty.kind {
1233 TypeKind::Bool => true,
1234 TypeKind::Union(members) => members.iter().all(|member| self.is_bool_like(member)),
1235 _ => false,
1236 }
1237 }
1238
1239 fn option_inner_type<'a>(&self, ty: &'a Type) -> Option<&'a Type> {
1240 match &ty.kind {
1241 TypeKind::Option(inner) => Some(inner.as_ref()),
1242 TypeKind::Union(members) => {
1243 for member in members {
1244 if let Some(inner) = self.option_inner_type(member) {
1245 return Some(inner);
1246 }
1247 }
1248 None
1249 }
1250 _ => None,
1251 }
1252 }
1253
1254 fn should_optionize(&self, left: &Type, right: &Type) -> bool {
1255 self.is_bool_like(left)
1256 && !self.is_bool_like(right)
1257 && self.option_inner_type(right).is_none()
1258 }
1259}