lust/typechecker/
mod.rs

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                    return Err(self.type_error(format!(
229                        "Strong ownership cycle detected: {}. Mark at least one field as 'ref' to break the cycle.",
230                        description
231                    )));
232                }
233            }
234        }
235
236        Ok(())
237    }
238
239    fn collect_strong_struct_targets(
240        &self,
241        ty: &Type,
242        parent_module: Option<&str>,
243        struct_defs: &HashMap<String, StructDef>,
244        simple_to_full: &HashMap<String, Vec<String>>,
245        out: &mut HashSet<String>,
246    ) {
247        match &ty.kind {
248            TypeKind::Named(name) => {
249                if let Some(resolved) = self.resolve_struct_name_for_cycle(
250                    name,
251                    parent_module,
252                    struct_defs,
253                    simple_to_full,
254                ) {
255                    out.insert(resolved);
256                }
257            }
258
259            TypeKind::Array(inner)
260            | TypeKind::Ref(inner)
261            | TypeKind::MutRef(inner)
262            | TypeKind::Option(inner) => {
263                self.collect_strong_struct_targets(
264                    inner,
265                    parent_module,
266                    struct_defs,
267                    simple_to_full,
268                    out,
269                );
270            }
271
272            TypeKind::Map(key, value) => {
273                self.collect_strong_struct_targets(
274                    key,
275                    parent_module,
276                    struct_defs,
277                    simple_to_full,
278                    out,
279                );
280                self.collect_strong_struct_targets(
281                    value,
282                    parent_module,
283                    struct_defs,
284                    simple_to_full,
285                    out,
286                );
287            }
288
289            TypeKind::Tuple(elements) | TypeKind::Union(elements) => {
290                for element in elements {
291                    self.collect_strong_struct_targets(
292                        element,
293                        parent_module,
294                        struct_defs,
295                        simple_to_full,
296                        out,
297                    );
298                }
299            }
300
301            TypeKind::Result(ok, err) => {
302                self.collect_strong_struct_targets(
303                    ok,
304                    parent_module,
305                    struct_defs,
306                    simple_to_full,
307                    out,
308                );
309                self.collect_strong_struct_targets(
310                    err,
311                    parent_module,
312                    struct_defs,
313                    simple_to_full,
314                    out,
315                );
316            }
317
318            TypeKind::GenericInstance { type_args, .. } => {
319                for arg in type_args {
320                    self.collect_strong_struct_targets(
321                        arg,
322                        parent_module,
323                        struct_defs,
324                        simple_to_full,
325                        out,
326                    );
327                }
328            }
329
330            _ => {}
331        }
332    }
333
334    fn resolve_struct_name_for_cycle(
335        &self,
336        name: &str,
337        parent_module: Option<&str>,
338        struct_defs: &HashMap<String, StructDef>,
339        simple_to_full: &HashMap<String, Vec<String>>,
340    ) -> Option<String> {
341        if struct_defs.contains_key(name) {
342            return Some(name.to_string());
343        }
344
345        if name.contains('.') {
346            return None;
347        }
348
349        if let Some(candidates) = simple_to_full.get(name) {
350            if candidates.len() == 1 {
351                return Some(candidates[0].clone());
352            }
353
354            if let Some(module) = parent_module {
355                for candidate in candidates {
356                    if let Some((candidate_module, _)) = candidate.rsplit_once('.') {
357                        if candidate_module == module {
358                            return Some(candidate.clone());
359                        }
360                    }
361                }
362            }
363        }
364
365        None
366    }
367
368    pub fn set_imports_by_module(&mut self, map: HashMap<String, ModuleImports>) {
369        self.imports_by_module = map;
370    }
371
372    pub fn take_type_info(&mut self) -> TypeCollection {
373        TypeCollection {
374            expr_types: mem::take(&mut self.expr_types_by_module),
375            variable_types: mem::take(&mut self.variable_types_by_module),
376        }
377    }
378
379    pub fn take_option_coercions(&mut self) -> HashMap<String, HashSet<Span>> {
380        let mut result: HashMap<String, HashSet<Span>> = HashMap::new();
381        let info = mem::take(&mut self.short_circuit_info);
382        for (module, entries) in info {
383            let mut spans: HashSet<Span> = HashSet::new();
384            for (span, entry) in entries {
385                if entry.option_inner.is_some() {
386                    spans.insert(span);
387                }
388            }
389            if !spans.is_empty() {
390                result.insert(module, spans);
391            }
392        }
393
394        result
395    }
396
397    pub fn function_signatures(&self) -> HashMap<String, type_env::FunctionSignature> {
398        self.env.function_signatures()
399    }
400
401    pub fn struct_definitions(&self) -> HashMap<String, StructDef> {
402        self.env.struct_definitions()
403    }
404
405    pub fn enum_definitions(&self) -> HashMap<String, EnumDef> {
406        self.env.enum_definitions()
407    }
408
409    fn register_module_init_locals(&mut self, items: &[Item]) -> Result<()> {
410        let module = match &self.current_module {
411            Some(m) => m.clone(),
412            None => return Ok(()),
413        };
414        let init_name = format!("__init@{}", module);
415        for item in items {
416            if let ItemKind::Function(func) = &item.kind {
417                if func.name == init_name {
418                    for stmt in &func.body {
419                        if let StmtKind::Local {
420                            bindings,
421                            ref mutable,
422                            initializer,
423                        } = &stmt.kind
424                        {
425                            self.check_local_stmt(
426                                bindings.as_slice(),
427                                *mutable,
428                                initializer.as_ref().map(|values| values.as_slice()),
429                            )?;
430                        }
431                    }
432                }
433            }
434        }
435
436        Ok(())
437    }
438
439    pub fn resolve_function_key(&self, name: &str) -> String {
440        if name.contains('.') || name.contains(':') {
441            return name.to_string();
442        }
443
444        if let Some(module) = &self.current_module {
445            if let Some(imports) = self.imports_by_module.get(module) {
446                if let Some(fq) = imports.function_aliases.get(name) {
447                    return fq.clone();
448                }
449            }
450
451            let qualified = format!("{}.{}", module, name);
452            if self.env.lookup_function(&qualified).is_some() {
453                return qualified;
454            }
455
456            if self.env.lookup_function(name).is_some() {
457                return name.to_string();
458            }
459
460            return qualified;
461        }
462
463        name.to_string()
464    }
465
466    pub fn resolve_module_alias(&self, alias: &str) -> Option<String> {
467        if let Some(module) = &self.current_module {
468            if let Some(imports) = self.imports_by_module.get(module) {
469                if let Some(m) = imports.module_aliases.get(alias) {
470                    return Some(m.clone());
471                }
472            }
473        }
474
475        None
476    }
477
478    pub fn resolve_type_key(&self, name: &str) -> String {
479        if let Some((head, tail)) = name.split_once('.') {
480            if let Some(module) = &self.current_module {
481                if let Some(imports) = self.imports_by_module.get(module) {
482                    if let Some(real_module) = imports.module_aliases.get(head) {
483                        if tail.is_empty() {
484                            return real_module.clone();
485                        } else {
486                            return format!("{}.{}", real_module, tail);
487                        }
488                    }
489                }
490            }
491
492            return name.to_string();
493        }
494
495        if self.env.lookup_struct(name).is_some()
496            || self.env.lookup_enum(name).is_some()
497            || self.env.lookup_trait(name).is_some()
498        {
499            return name.to_string();
500        }
501
502        if self.env.is_builtin_type(name) {
503            return name.to_string();
504        }
505
506        if let Some(module) = &self.current_module {
507            if let Some(imports) = self.imports_by_module.get(module) {
508                if let Some(fq) = imports.type_aliases.get(name) {
509                    return fq.clone();
510                }
511            }
512
513            return format!("{}.{}", module, name);
514        }
515
516        name.to_string()
517    }
518
519    fn register_type_definition(&mut self, item: &Item) -> Result<()> {
520        match &item.kind {
521            ItemKind::Struct(s) => {
522                let mut s2 = s.clone();
523                if let Some(module) = &self.current_module {
524                    if !s2.name.contains('.') {
525                        s2.name = format!("{}.{}", module, s2.name);
526                    }
527                }
528
529                self.env.register_struct(&s2)?;
530            }
531
532            ItemKind::Enum(e) => {
533                let mut e2 = e.clone();
534                if let Some(module) = &self.current_module {
535                    if !e2.name.contains('.') {
536                        e2.name = format!("{}.{}", module, e2.name);
537                    }
538                }
539
540                self.env.register_enum(&e2)?;
541            }
542
543            ItemKind::Trait(t) => {
544                let mut t2 = t.clone();
545                if let Some(module) = &self.current_module {
546                    if !t2.name.contains('.') {
547                        t2.name = format!("{}.{}", module, t2.name);
548                    }
549                }
550
551                self.env.register_trait(&t2)?;
552            }
553
554            ItemKind::TypeAlias {
555                name,
556                type_params,
557                target,
558            } => {
559                let qname = if let Some(module) = &self.current_module {
560                    if name.contains('.') {
561                        name.clone()
562                    } else {
563                        format!("{}.{}", module, name)
564                    }
565                } else {
566                    name.clone()
567                };
568                self.env
569                    .register_type_alias(qname, type_params.clone(), target.clone())?;
570            }
571
572            _ => {}
573        }
574
575        Ok(())
576    }
577
578    fn type_error(&self, message: String) -> LustError {
579        LustError::TypeError { message }
580    }
581
582    fn type_error_at(&self, message: String, span: Span) -> LustError {
583        if span.start_line > 0 {
584            LustError::TypeErrorWithSpan {
585                message,
586                line: span.start_line,
587                column: span.start_col,
588                module: self.current_module.clone(),
589            }
590        } else {
591            LustError::TypeError { message }
592        }
593    }
594
595    fn types_equal(&self, t1: &Type, t2: &Type) -> bool {
596        t1.kind == t2.kind
597    }
598
599    pub fn canonicalize_type(&self, ty: &Type) -> Type {
600        use crate::ast::TypeKind as TK;
601        match &ty.kind {
602            TK::Named(name) => Type::new(TK::Named(self.resolve_type_key(name)), ty.span),
603            TK::Array(inner) => {
604                Type::new(TK::Array(Box::new(self.canonicalize_type(inner))), ty.span)
605            }
606
607            TK::Tuple(elements) => Type::new(
608                TK::Tuple(elements.iter().map(|t| self.canonicalize_type(t)).collect()),
609                ty.span,
610            ),
611            TK::Option(inner) => {
612                Type::new(TK::Option(Box::new(self.canonicalize_type(inner))), ty.span)
613            }
614
615            TK::Result(ok, err) => Type::new(
616                TK::Result(
617                    Box::new(self.canonicalize_type(ok)),
618                    Box::new(self.canonicalize_type(err)),
619                ),
620                ty.span,
621            ),
622            TK::Map(k, v) => Type::new(
623                TK::Map(
624                    Box::new(self.canonicalize_type(k)),
625                    Box::new(self.canonicalize_type(v)),
626                ),
627                ty.span,
628            ),
629            TK::Ref(inner) => Type::new(TK::Ref(Box::new(self.canonicalize_type(inner))), ty.span),
630            TK::MutRef(inner) => {
631                Type::new(TK::MutRef(Box::new(self.canonicalize_type(inner))), ty.span)
632            }
633
634            TK::Pointer { mutable, pointee } => Type::new(
635                TK::Pointer {
636                    mutable: *mutable,
637                    pointee: Box::new(self.canonicalize_type(pointee)),
638                },
639                ty.span,
640            ),
641            _ => ty.clone(),
642        }
643    }
644
645    fn unify(&self, expected: &Type, actual: &Type) -> Result<()> {
646        let span = if actual.span.start_line > 0 {
647            Some(actual.span)
648        } else if expected.span.start_line > 0 {
649            Some(expected.span)
650        } else {
651            None
652        };
653        self.unify_at(expected, actual, span)
654    }
655
656    fn unify_at(&self, expected: &Type, actual: &Type, span: Option<Span>) -> Result<()> {
657        if matches!(expected.kind, TypeKind::Unknown) || matches!(actual.kind, TypeKind::Unknown) {
658            return Ok(());
659        }
660
661        if matches!(expected.kind, TypeKind::Infer) || matches!(actual.kind, TypeKind::Infer) {
662            return Ok(());
663        }
664
665        match (&expected.kind, &actual.kind) {
666            (TypeKind::Union(expected_types), TypeKind::Union(actual_types)) => {
667                if expected_types.len() != actual_types.len() {
668                    return Err(self.type_error(format!(
669                        "Union types have different number of members: expected {}, got {}",
670                        expected_types.len(),
671                        actual_types.len()
672                    )));
673                }
674
675                for exp_type in expected_types {
676                    let mut found = false;
677                    for act_type in actual_types {
678                        if self.types_equal(exp_type, act_type) {
679                            found = true;
680                            break;
681                        }
682                    }
683
684                    if !found {
685                        return Err(match span {
686                            Some(s) => self.type_error_at(
687                                format!(
688                                    "Union type member '{}' not found in actual union",
689                                    exp_type
690                                ),
691                                s,
692                            ),
693                            None => self.type_error(format!(
694                                "Union type member '{}' not found in actual union",
695                                exp_type
696                            )),
697                        });
698                    }
699                }
700
701                return Ok(());
702            }
703
704            (TypeKind::Union(expected_types), _) => {
705                for union_member in expected_types {
706                    if self.unify(union_member, actual).is_ok() {
707                        return Ok(());
708                    }
709                }
710
711                return Err(match span {
712                    Some(s) => self.type_error_at(
713                        format!("Type '{}' is not compatible with union type", actual),
714                        s,
715                    ),
716                    None => self.type_error(format!(
717                        "Type '{}' is not compatible with union type",
718                        actual
719                    )),
720                });
721            }
722
723            (_, TypeKind::Union(actual_types)) => {
724                for union_member in actual_types {
725                    self.unify(expected, union_member)?;
726                }
727
728                return Ok(());
729            }
730
731            _ => {}
732        }
733
734        match (&expected.kind, &actual.kind) {
735            (TypeKind::Tuple(expected_elems), TypeKind::Tuple(actual_elems)) => {
736                if expected_elems.len() != actual_elems.len() {
737                    return Err(match span {
738                        Some(s) => self.type_error_at(
739                            format!(
740                                "Tuple length mismatch: expected {} element(s), got {}",
741                                expected_elems.len(),
742                                actual_elems.len()
743                            ),
744                            s,
745                        ),
746                        None => self.type_error(format!(
747                            "Tuple length mismatch: expected {} element(s), got {}",
748                            expected_elems.len(),
749                            actual_elems.len()
750                        )),
751                    });
752                }
753
754                for (exp_elem, act_elem) in expected_elems.iter().zip(actual_elems.iter()) {
755                    self.unify(exp_elem, act_elem)?;
756                }
757
758                return Ok(());
759            }
760
761            (TypeKind::Tuple(_), _) | (_, TypeKind::Tuple(_)) => {
762                return Err(match span {
763                    Some(s) => self.type_error_at(
764                        format!("Tuple type is not compatible with type '{}'", actual),
765                        s,
766                    ),
767                    None => self.type_error(format!(
768                        "Tuple type is not compatible with type '{}'",
769                        actual
770                    )),
771                })
772            }
773
774            (TypeKind::Named(name), TypeKind::Array(_))
775            | (TypeKind::Array(_), TypeKind::Named(name))
776                if name == "Array" =>
777            {
778                return Ok(());
779            }
780
781            (TypeKind::Array(exp_el), TypeKind::Array(act_el)) => {
782                if matches!(exp_el.kind, TypeKind::Unknown | TypeKind::Infer)
783                    || matches!(act_el.kind, TypeKind::Unknown | TypeKind::Infer)
784                {
785                    return Ok(());
786                } else {
787                    return self.unify(exp_el, act_el);
788                }
789            }
790
791            (TypeKind::Map(exp_key, exp_value), TypeKind::Map(act_key, act_value)) => {
792                self.unify(exp_key, act_key)?;
793                return self.unify(exp_value, act_value);
794            }
795
796            (TypeKind::Named(name), TypeKind::Option(_))
797            | (TypeKind::Option(_), TypeKind::Named(name))
798                if name == "Option" =>
799            {
800                return Ok(());
801            }
802
803            (TypeKind::Option(exp_inner), TypeKind::Option(act_inner)) => {
804                if matches!(exp_inner.kind, TypeKind::Unknown | TypeKind::Infer)
805                    || matches!(act_inner.kind, TypeKind::Unknown | TypeKind::Infer)
806                {
807                    return Ok(());
808                } else {
809                    return self.unify(exp_inner, act_inner);
810                }
811            }
812
813            (TypeKind::Named(name), TypeKind::Result(_, _))
814            | (TypeKind::Result(_, _), TypeKind::Named(name))
815                if name == "Result" =>
816            {
817                return Ok(());
818            }
819
820            (TypeKind::Result(exp_ok, exp_err), TypeKind::Result(act_ok, act_err)) => {
821                if matches!(exp_ok.kind, TypeKind::Unknown | TypeKind::Infer)
822                    || matches!(act_ok.kind, TypeKind::Unknown | TypeKind::Infer)
823                {
824                    if matches!(exp_err.kind, TypeKind::Unknown | TypeKind::Infer)
825                        || matches!(act_err.kind, TypeKind::Unknown | TypeKind::Infer)
826                    {
827                        return Ok(());
828                    } else {
829                        return self.unify(exp_err, act_err);
830                    }
831                } else {
832                    self.unify(exp_ok, act_ok)?;
833                    return self.unify(exp_err, act_err);
834                }
835            }
836
837            _ => {}
838        }
839
840        if self.types_equal(expected, actual) {
841            Ok(())
842        } else {
843            Err(match span {
844                Some(s) => self.type_error_at(
845                    format!("Type mismatch: expected '{}', got '{}'", expected, actual),
846                    s,
847                ),
848                None => self.type_error(format!(
849                    "Type mismatch: expected '{}', got '{}'",
850                    expected, actual
851                )),
852            })
853        }
854    }
855
856    fn types_compatible(&self, expected: &Type, actual: &Type) -> bool {
857        if matches!(expected.kind, TypeKind::Unknown) || matches!(actual.kind, TypeKind::Unknown) {
858            return true;
859        }
860
861        if matches!(expected.kind, TypeKind::Infer) || matches!(actual.kind, TypeKind::Infer) {
862            return true;
863        }
864
865        match (&expected.kind, &actual.kind) {
866            (TypeKind::Generic(_), TypeKind::Generic(_)) => return true,
867            (TypeKind::Generic(_), _) | (_, TypeKind::Generic(_)) => return true,
868            _ => {}
869        }
870
871        match (&expected.kind, &actual.kind) {
872            (TypeKind::Array(e1), TypeKind::Array(e2)) => {
873                return self.types_compatible(e1, e2);
874            }
875
876            (TypeKind::Named(name), TypeKind::Array(_))
877            | (TypeKind::Array(_), TypeKind::Named(name))
878                if name == "Array" =>
879            {
880                return true;
881            }
882
883            _ => {}
884        }
885
886        match (&expected.kind, &actual.kind) {
887            (TypeKind::Map(k1, v1), TypeKind::Map(k2, v2)) => {
888                return self.types_compatible(k1, k2) && self.types_compatible(v1, v2);
889            }
890
891            _ => {}
892        }
893
894        match (&expected.kind, &actual.kind) {
895            (TypeKind::Option(t1), TypeKind::Option(t2)) => {
896                return self.types_compatible(t1, t2);
897            }
898
899            (TypeKind::Named(name), TypeKind::Option(_))
900            | (TypeKind::Option(_), TypeKind::Named(name))
901                if name == "Option" =>
902            {
903                return true;
904            }
905
906            _ => {}
907        }
908
909        match (&expected.kind, &actual.kind) {
910            (TypeKind::Result(ok1, err1), TypeKind::Result(ok2, err2)) => {
911                return self.types_compatible(ok1, ok2) && self.types_compatible(err1, err2);
912            }
913
914            (TypeKind::Named(name), TypeKind::Result(_, _))
915            | (TypeKind::Result(_, _), TypeKind::Named(name))
916                if name == "Result" =>
917            {
918                return true;
919            }
920
921            _ => {}
922        }
923
924        match (&expected.kind, &actual.kind) {
925            (
926                TypeKind::Function {
927                    params: p1,
928                    return_type: r1,
929                },
930                TypeKind::Function {
931                    params: p2,
932                    return_type: r2,
933                },
934            ) => {
935                if p1.len() != p2.len() {
936                    return false;
937                }
938
939                for (t1, t2) in p1.iter().zip(p2.iter()) {
940                    if !self.types_compatible(t1, t2) {
941                        return false;
942                    }
943                }
944
945                return self.types_compatible(r1, r2);
946            }
947
948            _ => {}
949        }
950
951        self.types_equal(expected, actual)
952    }
953
954    fn unify_with_bounds(&self, expected: &Type, actual: &Type) -> Result<()> {
955        if let TypeKind::Generic(type_param) = &expected.kind {
956            if let Some(trait_names) = self.current_trait_bounds.get(type_param) {
957                for trait_name in trait_names {
958                    if !self.env.type_implements_trait(actual, trait_name) {
959                        return Err(self.type_error(format!(
960                            "Type '{}' does not implement required trait '{}'",
961                            actual, trait_name
962                        )));
963                    }
964                }
965
966                return Ok(());
967            }
968
969            return Ok(());
970        }
971
972        self.unify(expected, actual)
973    }
974
975    fn record_short_circuit_info(&mut self, span: Span, info: &ShortCircuitInfo) {
976        let truthy = info.truthy.as_ref().map(|ty| self.canonicalize_type(ty));
977        let falsy = info.falsy.as_ref().map(|ty| self.canonicalize_type(ty));
978        let option_inner = info
979            .option_inner
980            .as_ref()
981            .map(|ty| self.canonicalize_type(ty));
982        let module_key = self.current_module_key();
983        self.short_circuit_info
984            .entry(module_key)
985            .or_default()
986            .insert(
987                span,
988                ShortCircuitInfo {
989                    truthy,
990                    falsy,
991                    option_inner,
992                },
993            );
994    }
995
996    fn short_circuit_profile(&self, expr: &Expr, ty: &Type) -> ShortCircuitInfo {
997        let module_key = self
998            .current_module
999            .as_ref()
1000            .map(String::as_str)
1001            .unwrap_or("");
1002        if let Some(module_map) = self.short_circuit_info.get(module_key) {
1003            if let Some(info) = module_map.get(&expr.span) {
1004                return info.clone();
1005            }
1006        }
1007
1008        ShortCircuitInfo {
1009            truthy: if self.type_can_be_truthy(ty) {
1010                Some(self.canonicalize_type(ty))
1011            } else {
1012                None
1013            },
1014            falsy: self.extract_falsy_type(ty),
1015            option_inner: None,
1016        }
1017    }
1018
1019    fn current_module_key(&self) -> String {
1020        self.current_module
1021            .as_ref()
1022            .cloned()
1023            .unwrap_or_else(|| "".to_string())
1024    }
1025
1026    fn clear_option_for_span(&mut self, span: Span) {
1027        let module_key = self.current_module_key();
1028        if let Some(module_map) = self.short_circuit_info.get_mut(&module_key) {
1029            if let Some(info) = module_map.get_mut(&span) {
1030                info.option_inner = None;
1031            }
1032        }
1033    }
1034
1035    fn type_can_be_truthy(&self, ty: &Type) -> bool {
1036        match &ty.kind {
1037            TypeKind::Union(members) => {
1038                members.iter().any(|member| self.type_can_be_truthy(member))
1039            }
1040            TypeKind::Bool => true,
1041            TypeKind::Unknown => true,
1042            _ => true,
1043        }
1044    }
1045
1046    fn type_can_be_falsy(&self, ty: &Type) -> bool {
1047        match &ty.kind {
1048            TypeKind::Union(members) => members.iter().any(|member| self.type_can_be_falsy(member)),
1049            TypeKind::Bool => true,
1050            TypeKind::Unknown => true,
1051            TypeKind::Option(_) => true,
1052            _ => false,
1053        }
1054    }
1055
1056    fn extract_falsy_type(&self, ty: &Type) -> Option<Type> {
1057        match &ty.kind {
1058            TypeKind::Bool => Some(Type::new(TypeKind::Bool, ty.span)),
1059            TypeKind::Unknown => Some(Type::new(TypeKind::Unknown, ty.span)),
1060            TypeKind::Option(inner) => Some(Type::new(
1061                TypeKind::Option(Box::new(self.canonicalize_type(inner))),
1062                ty.span,
1063            )),
1064            TypeKind::Union(members) => {
1065                let mut parts = Vec::new();
1066                for member in members {
1067                    if let Some(part) = self.extract_falsy_type(member) {
1068                        parts.push(part);
1069                    }
1070                }
1071                self.merge_optional_types(parts)
1072            }
1073            _ => None,
1074        }
1075    }
1076
1077    fn merge_optional_types(&self, types: Vec<Type>) -> Option<Type> {
1078        if types.is_empty() {
1079            return None;
1080        }
1081
1082        Some(self.make_union_from_types(types))
1083    }
1084
1085    fn make_union_from_types(&self, types: Vec<Type>) -> Type {
1086        let mut flat: Vec<Type> = Vec::new();
1087        for ty in types {
1088            let canonical = self.canonicalize_type(&ty);
1089            match &canonical.kind {
1090                TypeKind::Union(members) => {
1091                    for member in members {
1092                        self.push_unique_type(&mut flat, member.clone());
1093                    }
1094                }
1095                _ => self.push_unique_type(&mut flat, canonical),
1096            }
1097        }
1098
1099        match flat.len() {
1100            0 => Type::new(TypeKind::Unknown, Self::dummy_span()),
1101            1 => flat.into_iter().next().unwrap(),
1102            _ => Type::new(TypeKind::Union(flat), Self::dummy_span()),
1103        }
1104    }
1105
1106    fn push_unique_type(&self, list: &mut Vec<Type>, candidate: Type) {
1107        if !list
1108            .iter()
1109            .any(|existing| self.types_equal(existing, &candidate))
1110        {
1111            list.push(candidate);
1112        }
1113    }
1114
1115    fn combine_truthy_falsy(&self, truthy: Option<Type>, falsy: Option<Type>) -> Type {
1116        match (truthy, falsy) {
1117            (Some(t), Some(f)) => self.make_union_from_types(vec![t, f]),
1118            (Some(t), None) => t,
1119            (None, Some(f)) => f,
1120            (None, None) => Type::new(TypeKind::Unknown, Self::dummy_span()),
1121        }
1122    }
1123
1124    fn is_bool_like(&self, ty: &Type) -> bool {
1125        match &ty.kind {
1126            TypeKind::Bool => true,
1127            TypeKind::Union(members) => members.iter().all(|member| self.is_bool_like(member)),
1128            _ => false,
1129        }
1130    }
1131
1132    fn option_inner_type<'a>(&self, ty: &'a Type) -> Option<&'a Type> {
1133        match &ty.kind {
1134            TypeKind::Option(inner) => Some(inner.as_ref()),
1135            TypeKind::Union(members) => {
1136                for member in members {
1137                    if let Some(inner) = self.option_inner_type(member) {
1138                        return Some(inner);
1139                    }
1140                }
1141                None
1142            }
1143            _ => None,
1144        }
1145    }
1146
1147    fn should_optionize(&self, left: &Type, right: &Type) -> bool {
1148        self.is_bool_like(left)
1149            && !self.is_bool_like(right)
1150            && self.option_inner_type(right).is_none()
1151    }
1152}
lust/typechecker/mod.rs

lust/typechecker/
mod.rs
