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-rw-r--r--crates/hir_ty/src/autoderef.rs131
-rw-r--r--crates/hir_ty/src/db.rs158
-rw-r--r--crates/hir_ty/src/diagnostics.rs444
-rw-r--r--crates/hir_ty/src/diagnostics/expr.rs569
-rw-r--r--crates/hir_ty/src/diagnostics/match_check.rs1421
-rw-r--r--crates/hir_ty/src/diagnostics/unsafe_check.rs205
-rw-r--r--crates/hir_ty/src/display.rs632
-rw-r--r--crates/hir_ty/src/infer.rs802
-rw-r--r--crates/hir_ty/src/infer/coerce.rs197
-rw-r--r--crates/hir_ty/src/infer/expr.rs873
-rw-r--r--crates/hir_ty/src/infer/pat.rs241
-rw-r--r--crates/hir_ty/src/infer/path.rs287
-rw-r--r--crates/hir_ty/src/infer/unify.rs474
-rw-r--r--crates/hir_ty/src/lib.rs1078
-rw-r--r--crates/hir_ty/src/lower.rs1242
-rw-r--r--crates/hir_ty/src/method_resolution.rs769
-rw-r--r--crates/hir_ty/src/op.rs58
-rw-r--r--crates/hir_ty/src/primitive.rs139
-rw-r--r--crates/hir_ty/src/test_db.rs136
-rw-r--r--crates/hir_ty/src/tests.rs359
-rw-r--r--crates/hir_ty/src/tests/coercion.rs861
-rw-r--r--crates/hir_ty/src/tests/display_source_code.rs41
-rw-r--r--crates/hir_ty/src/tests/macros.rs787
-rw-r--r--crates/hir_ty/src/tests/method_resolution.rs1053
-rw-r--r--crates/hir_ty/src/tests/never_type.rs409
-rw-r--r--crates/hir_ty/src/tests/patterns.rs656
-rw-r--r--crates/hir_ty/src/tests/regression.rs842
-rw-r--r--crates/hir_ty/src/tests/simple.rs2218
-rw-r--r--crates/hir_ty/src/tests/traits.rs3113
-rw-r--r--crates/hir_ty/src/traits.rs285
-rw-r--r--crates/hir_ty/src/traits/chalk.rs589
-rw-r--r--crates/hir_ty/src/traits/chalk/interner.rs383
-rw-r--r--crates/hir_ty/src/traits/chalk/mapping.rs787
-rw-r--r--crates/hir_ty/src/traits/chalk/tls.rs358
-rw-r--r--crates/hir_ty/src/utils.rs257
35 files changed, 22854 insertions, 0 deletions
diff --git a/crates/hir_ty/src/autoderef.rs b/crates/hir_ty/src/autoderef.rs
new file mode 100644
index 000000000..ece68183e
--- /dev/null
+++ b/crates/hir_ty/src/autoderef.rs
@@ -0,0 +1,131 @@
1//! In certain situations, rust automatically inserts derefs as necessary: for
2//! example, field accesses `foo.bar` still work when `foo` is actually a
3//! reference to a type with the field `bar`. This is an approximation of the
4//! logic in rustc (which lives in librustc_typeck/check/autoderef.rs).
5
6use std::iter::successors;
7
8use base_db::CrateId;
9use hir_def::lang_item::LangItemTarget;
10use hir_expand::name::name;
11use log::{info, warn};
12
13use crate::{
14 db::HirDatabase,
15 traits::{InEnvironment, Solution},
16 utils::generics,
17 BoundVar, Canonical, DebruijnIndex, Obligation, Substs, TraitRef, Ty,
18};
19
20const AUTODEREF_RECURSION_LIMIT: usize = 10;
21
22pub fn autoderef<'a>(
23 db: &'a dyn HirDatabase,
24 krate: Option<CrateId>,
25 ty: InEnvironment<Canonical<Ty>>,
26) -> impl Iterator<Item = Canonical<Ty>> + 'a {
27 let InEnvironment { value: ty, environment } = ty;
28 successors(Some(ty), move |ty| {
29 deref(db, krate?, InEnvironment { value: ty, environment: environment.clone() })
30 })
31 .take(AUTODEREF_RECURSION_LIMIT)
32}
33
34pub(crate) fn deref(
35 db: &dyn HirDatabase,
36 krate: CrateId,
37 ty: InEnvironment<&Canonical<Ty>>,
38) -> Option<Canonical<Ty>> {
39 if let Some(derefed) = ty.value.value.builtin_deref() {
40 Some(Canonical { value: derefed, kinds: ty.value.kinds.clone() })
41 } else {
42 deref_by_trait(db, krate, ty)
43 }
44}
45
46fn deref_by_trait(
47 db: &dyn HirDatabase,
48 krate: CrateId,
49 ty: InEnvironment<&Canonical<Ty>>,
50) -> Option<Canonical<Ty>> {
51 let deref_trait = match db.lang_item(krate, "deref".into())? {
52 LangItemTarget::TraitId(it) => it,
53 _ => return None,
54 };
55 let target = db.trait_data(deref_trait).associated_type_by_name(&name![Target])?;
56
57 let generic_params = generics(db.upcast(), target.into());
58 if generic_params.len() != 1 {
59 // the Target type + Deref trait should only have one generic parameter,
60 // namely Deref's Self type
61 return None;
62 }
63
64 // FIXME make the Canonical / bound var handling nicer
65
66 let parameters =
67 Substs::build_for_generics(&generic_params).push(ty.value.value.clone()).build();
68
69 // Check that the type implements Deref at all
70 let trait_ref = TraitRef { trait_: deref_trait, substs: parameters.clone() };
71 let implements_goal = Canonical {
72 kinds: ty.value.kinds.clone(),
73 value: InEnvironment {
74 value: Obligation::Trait(trait_ref),
75 environment: ty.environment.clone(),
76 },
77 };
78 if db.trait_solve(krate, implements_goal).is_none() {
79 return None;
80 }
81
82 // Now do the assoc type projection
83 let projection = super::traits::ProjectionPredicate {
84 ty: Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, ty.value.kinds.len())),
85 projection_ty: super::ProjectionTy { associated_ty: target, parameters },
86 };
87
88 let obligation = super::Obligation::Projection(projection);
89
90 let in_env = InEnvironment { value: obligation, environment: ty.environment };
91
92 let canonical =
93 Canonical::new(in_env, ty.value.kinds.iter().copied().chain(Some(super::TyKind::General)));
94
95 let solution = db.trait_solve(krate, canonical)?;
96
97 match &solution {
98 Solution::Unique(vars) => {
99 // FIXME: vars may contain solutions for any inference variables
100 // that happened to be inside ty. To correctly handle these, we
101 // would have to pass the solution up to the inference context, but
102 // that requires a larger refactoring (especially if the deref
103 // happens during method resolution). So for the moment, we just
104 // check that we're not in the situation we're we would actually
105 // need to handle the values of the additional variables, i.e.
106 // they're just being 'passed through'. In the 'standard' case where
107 // we have `impl<T> Deref for Foo<T> { Target = T }`, that should be
108 // the case.
109
110 // FIXME: if the trait solver decides to truncate the type, these
111 // assumptions will be broken. We would need to properly introduce
112 // new variables in that case
113
114 for i in 1..vars.0.kinds.len() {
115 if vars.0.value[i - 1] != Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, i - 1))
116 {
117 warn!("complex solution for derefing {:?}: {:?}, ignoring", ty.value, solution);
118 return None;
119 }
120 }
121 Some(Canonical {
122 value: vars.0.value[vars.0.value.len() - 1].clone(),
123 kinds: vars.0.kinds.clone(),
124 })
125 }
126 Solution::Ambig(_) => {
127 info!("Ambiguous solution for derefing {:?}: {:?}", ty.value, solution);
128 None
129 }
130 }
131}
diff --git a/crates/hir_ty/src/db.rs b/crates/hir_ty/src/db.rs
new file mode 100644
index 000000000..25cf9eb7f
--- /dev/null
+++ b/crates/hir_ty/src/db.rs
@@ -0,0 +1,158 @@
1//! FIXME: write short doc here
2
3use std::sync::Arc;
4
5use arena::map::ArenaMap;
6use base_db::{impl_intern_key, salsa, CrateId, Upcast};
7use hir_def::{
8 db::DefDatabase, expr::ExprId, DefWithBodyId, FunctionId, GenericDefId, ImplId, LocalFieldId,
9 TypeParamId, VariantId,
10};
11
12use crate::{
13 method_resolution::{InherentImpls, TraitImpls},
14 traits::chalk,
15 Binders, CallableDefId, GenericPredicate, InferenceResult, OpaqueTyId, PolyFnSig,
16 ReturnTypeImplTraits, TraitRef, Ty, TyDefId, ValueTyDefId,
17};
18use hir_expand::name::Name;
19
20#[salsa::query_group(HirDatabaseStorage)]
21pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
22 #[salsa::invoke(infer_wait)]
23 #[salsa::transparent]
24 fn infer(&self, def: DefWithBodyId) -> Arc<InferenceResult>;
25
26 #[salsa::invoke(crate::infer::infer_query)]
27 fn infer_query(&self, def: DefWithBodyId) -> Arc<InferenceResult>;
28
29 #[salsa::invoke(crate::lower::ty_query)]
30 #[salsa::cycle(crate::lower::ty_recover)]
31 fn ty(&self, def: TyDefId) -> Binders<Ty>;
32
33 #[salsa::invoke(crate::lower::value_ty_query)]
34 fn value_ty(&self, def: ValueTyDefId) -> Binders<Ty>;
35
36 #[salsa::invoke(crate::lower::impl_self_ty_query)]
37 #[salsa::cycle(crate::lower::impl_self_ty_recover)]
38 fn impl_self_ty(&self, def: ImplId) -> Binders<Ty>;
39
40 #[salsa::invoke(crate::lower::impl_trait_query)]
41 fn impl_trait(&self, def: ImplId) -> Option<Binders<TraitRef>>;
42
43 #[salsa::invoke(crate::lower::field_types_query)]
44 fn field_types(&self, var: VariantId) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>>;
45
46 #[salsa::invoke(crate::callable_item_sig)]
47 fn callable_item_signature(&self, def: CallableDefId) -> PolyFnSig;
48
49 #[salsa::invoke(crate::lower::return_type_impl_traits)]
50 fn return_type_impl_traits(
51 &self,
52 def: FunctionId,
53 ) -> Option<Arc<Binders<ReturnTypeImplTraits>>>;
54
55 #[salsa::invoke(crate::lower::generic_predicates_for_param_query)]
56 #[salsa::cycle(crate::lower::generic_predicates_for_param_recover)]
57 fn generic_predicates_for_param(
58 &self,
59 param_id: TypeParamId,
60 ) -> Arc<[Binders<GenericPredicate>]>;
61
62 #[salsa::invoke(crate::lower::generic_predicates_query)]
63 fn generic_predicates(&self, def: GenericDefId) -> Arc<[Binders<GenericPredicate>]>;
64
65 #[salsa::invoke(crate::lower::generic_defaults_query)]
66 fn generic_defaults(&self, def: GenericDefId) -> Arc<[Binders<Ty>]>;
67
68 #[salsa::invoke(InherentImpls::inherent_impls_in_crate_query)]
69 fn inherent_impls_in_crate(&self, krate: CrateId) -> Arc<InherentImpls>;
70
71 #[salsa::invoke(TraitImpls::trait_impls_in_crate_query)]
72 fn trait_impls_in_crate(&self, krate: CrateId) -> Arc<TraitImpls>;
73
74 #[salsa::invoke(TraitImpls::trait_impls_in_deps_query)]
75 fn trait_impls_in_deps(&self, krate: CrateId) -> Arc<TraitImpls>;
76
77 // Interned IDs for Chalk integration
78 #[salsa::interned]
79 fn intern_callable_def(&self, callable_def: CallableDefId) -> InternedCallableDefId;
80 #[salsa::interned]
81 fn intern_type_param_id(&self, param_id: TypeParamId) -> GlobalTypeParamId;
82 #[salsa::interned]
83 fn intern_impl_trait_id(&self, id: OpaqueTyId) -> InternedOpaqueTyId;
84 #[salsa::interned]
85 fn intern_closure(&self, id: (DefWithBodyId, ExprId)) -> ClosureId;
86
87 #[salsa::invoke(chalk::associated_ty_data_query)]
88 fn associated_ty_data(&self, id: chalk::AssocTypeId) -> Arc<chalk::AssociatedTyDatum>;
89
90 #[salsa::invoke(chalk::trait_datum_query)]
91 fn trait_datum(&self, krate: CrateId, trait_id: chalk::TraitId) -> Arc<chalk::TraitDatum>;
92
93 #[salsa::invoke(chalk::struct_datum_query)]
94 fn struct_datum(&self, krate: CrateId, struct_id: chalk::AdtId) -> Arc<chalk::StructDatum>;
95
96 #[salsa::invoke(crate::traits::chalk::impl_datum_query)]
97 fn impl_datum(&self, krate: CrateId, impl_id: chalk::ImplId) -> Arc<chalk::ImplDatum>;
98
99 #[salsa::invoke(crate::traits::chalk::fn_def_datum_query)]
100 fn fn_def_datum(&self, krate: CrateId, fn_def_id: chalk::FnDefId) -> Arc<chalk::FnDefDatum>;
101
102 #[salsa::invoke(crate::traits::chalk::associated_ty_value_query)]
103 fn associated_ty_value(
104 &self,
105 krate: CrateId,
106 id: chalk::AssociatedTyValueId,
107 ) -> Arc<chalk::AssociatedTyValue>;
108
109 #[salsa::invoke(crate::traits::trait_solve_query)]
110 fn trait_solve(
111 &self,
112 krate: CrateId,
113 goal: crate::Canonical<crate::InEnvironment<crate::Obligation>>,
114 ) -> Option<crate::traits::Solution>;
115
116 #[salsa::invoke(crate::traits::chalk::program_clauses_for_chalk_env_query)]
117 fn program_clauses_for_chalk_env(
118 &self,
119 krate: CrateId,
120 env: chalk_ir::Environment<chalk::Interner>,
121 ) -> chalk_ir::ProgramClauses<chalk::Interner>;
122}
123
124fn infer_wait(db: &impl HirDatabase, def: DefWithBodyId) -> Arc<InferenceResult> {
125 let _p = profile::span("infer:wait").detail(|| match def {
126 DefWithBodyId::FunctionId(it) => db.function_data(it).name.to_string(),
127 DefWithBodyId::StaticId(it) => {
128 db.static_data(it).name.clone().unwrap_or_else(Name::missing).to_string()
129 }
130 DefWithBodyId::ConstId(it) => {
131 db.const_data(it).name.clone().unwrap_or_else(Name::missing).to_string()
132 }
133 });
134 db.infer_query(def)
135}
136
137#[test]
138fn hir_database_is_object_safe() {
139 fn _assert_object_safe(_: &dyn HirDatabase) {}
140}
141
142#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
143pub struct GlobalTypeParamId(salsa::InternId);
144impl_intern_key!(GlobalTypeParamId);
145
146#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
147pub struct InternedOpaqueTyId(salsa::InternId);
148impl_intern_key!(InternedOpaqueTyId);
149
150#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
151pub struct ClosureId(salsa::InternId);
152impl_intern_key!(ClosureId);
153
154/// This exists just for Chalk, because Chalk just has a single `FnDefId` where
155/// we have different IDs for struct and enum variant constructors.
156#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
157pub struct InternedCallableDefId(salsa::InternId);
158impl_intern_key!(InternedCallableDefId);
diff --git a/crates/hir_ty/src/diagnostics.rs b/crates/hir_ty/src/diagnostics.rs
new file mode 100644
index 000000000..ae0cf8d09
--- /dev/null
+++ b/crates/hir_ty/src/diagnostics.rs
@@ -0,0 +1,444 @@
1//! FIXME: write short doc here
2mod expr;
3mod match_check;
4mod unsafe_check;
5
6use std::any::Any;
7
8use hir_def::DefWithBodyId;
9use hir_expand::diagnostics::{Diagnostic, DiagnosticSink};
10use hir_expand::{name::Name, HirFileId, InFile};
11use stdx::format_to;
12use syntax::{ast, AstPtr, SyntaxNodePtr};
13
14use crate::db::HirDatabase;
15
16pub use crate::diagnostics::expr::{record_literal_missing_fields, record_pattern_missing_fields};
17
18pub fn validate_body(db: &dyn HirDatabase, owner: DefWithBodyId, sink: &mut DiagnosticSink<'_>) {
19 let _p = profile::span("validate_body");
20 let infer = db.infer(owner);
21 infer.add_diagnostics(db, owner, sink);
22 let mut validator = expr::ExprValidator::new(owner, infer.clone(), sink);
23 validator.validate_body(db);
24 let mut validator = unsafe_check::UnsafeValidator::new(owner, infer, sink);
25 validator.validate_body(db);
26}
27
28#[derive(Debug)]
29pub struct NoSuchField {
30 pub file: HirFileId,
31 pub field: AstPtr<ast::RecordExprField>,
32}
33
34impl Diagnostic for NoSuchField {
35 fn message(&self) -> String {
36 "no such field".to_string()
37 }
38
39 fn display_source(&self) -> InFile<SyntaxNodePtr> {
40 InFile::new(self.file, self.field.clone().into())
41 }
42
43 fn as_any(&self) -> &(dyn Any + Send + 'static) {
44 self
45 }
46}
47
48#[derive(Debug)]
49pub struct MissingFields {
50 pub file: HirFileId,
51 pub field_list_parent: AstPtr<ast::RecordExpr>,
52 pub field_list_parent_path: Option<AstPtr<ast::Path>>,
53 pub missed_fields: Vec<Name>,
54}
55
56impl Diagnostic for MissingFields {
57 fn message(&self) -> String {
58 let mut buf = String::from("Missing structure fields:\n");
59 for field in &self.missed_fields {
60 format_to!(buf, "- {}\n", field);
61 }
62 buf
63 }
64
65 fn display_source(&self) -> InFile<SyntaxNodePtr> {
66 InFile {
67 file_id: self.file,
68 value: self
69 .field_list_parent_path
70 .clone()
71 .map(SyntaxNodePtr::from)
72 .unwrap_or_else(|| self.field_list_parent.clone().into()),
73 }
74 }
75
76 fn as_any(&self) -> &(dyn Any + Send + 'static) {
77 self
78 }
79}
80
81#[derive(Debug)]
82pub struct MissingPatFields {
83 pub file: HirFileId,
84 pub field_list_parent: AstPtr<ast::RecordPat>,
85 pub field_list_parent_path: Option<AstPtr<ast::Path>>,
86 pub missed_fields: Vec<Name>,
87}
88
89impl Diagnostic for MissingPatFields {
90 fn message(&self) -> String {
91 let mut buf = String::from("Missing structure fields:\n");
92 for field in &self.missed_fields {
93 format_to!(buf, "- {}\n", field);
94 }
95 buf
96 }
97 fn display_source(&self) -> InFile<SyntaxNodePtr> {
98 InFile {
99 file_id: self.file,
100 value: self
101 .field_list_parent_path
102 .clone()
103 .map(SyntaxNodePtr::from)
104 .unwrap_or_else(|| self.field_list_parent.clone().into()),
105 }
106 }
107 fn as_any(&self) -> &(dyn Any + Send + 'static) {
108 self
109 }
110}
111
112#[derive(Debug)]
113pub struct MissingMatchArms {
114 pub file: HirFileId,
115 pub match_expr: AstPtr<ast::Expr>,
116 pub arms: AstPtr<ast::MatchArmList>,
117}
118
119impl Diagnostic for MissingMatchArms {
120 fn message(&self) -> String {
121 String::from("Missing match arm")
122 }
123 fn display_source(&self) -> InFile<SyntaxNodePtr> {
124 InFile { file_id: self.file, value: self.match_expr.clone().into() }
125 }
126 fn as_any(&self) -> &(dyn Any + Send + 'static) {
127 self
128 }
129}
130
131#[derive(Debug)]
132pub struct MissingOkInTailExpr {
133 pub file: HirFileId,
134 pub expr: AstPtr<ast::Expr>,
135}
136
137impl Diagnostic for MissingOkInTailExpr {
138 fn message(&self) -> String {
139 "wrap return expression in Ok".to_string()
140 }
141 fn display_source(&self) -> InFile<SyntaxNodePtr> {
142 InFile { file_id: self.file, value: self.expr.clone().into() }
143 }
144 fn as_any(&self) -> &(dyn Any + Send + 'static) {
145 self
146 }
147}
148
149#[derive(Debug)]
150pub struct BreakOutsideOfLoop {
151 pub file: HirFileId,
152 pub expr: AstPtr<ast::Expr>,
153}
154
155impl Diagnostic for BreakOutsideOfLoop {
156 fn message(&self) -> String {
157 "break outside of loop".to_string()
158 }
159 fn display_source(&self) -> InFile<SyntaxNodePtr> {
160 InFile { file_id: self.file, value: self.expr.clone().into() }
161 }
162 fn as_any(&self) -> &(dyn Any + Send + 'static) {
163 self
164 }
165}
166
167#[derive(Debug)]
168pub struct MissingUnsafe {
169 pub file: HirFileId,
170 pub expr: AstPtr<ast::Expr>,
171}
172
173impl Diagnostic for MissingUnsafe {
174 fn message(&self) -> String {
175 format!("This operation is unsafe and requires an unsafe function or block")
176 }
177 fn display_source(&self) -> InFile<SyntaxNodePtr> {
178 InFile { file_id: self.file, value: self.expr.clone().into() }
179 }
180 fn as_any(&self) -> &(dyn Any + Send + 'static) {
181 self
182 }
183}
184
185#[derive(Debug)]
186pub struct MismatchedArgCount {
187 pub file: HirFileId,
188 pub call_expr: AstPtr<ast::Expr>,
189 pub expected: usize,
190 pub found: usize,
191}
192
193impl Diagnostic for MismatchedArgCount {
194 fn message(&self) -> String {
195 let s = if self.expected == 1 { "" } else { "s" };
196 format!("Expected {} argument{}, found {}", self.expected, s, self.found)
197 }
198 fn display_source(&self) -> InFile<SyntaxNodePtr> {
199 InFile { file_id: self.file, value: self.call_expr.clone().into() }
200 }
201 fn as_any(&self) -> &(dyn Any + Send + 'static) {
202 self
203 }
204 fn is_experimental(&self) -> bool {
205 true
206 }
207}
208
209#[cfg(test)]
210mod tests {
211 use base_db::{fixture::WithFixture, FileId, SourceDatabase, SourceDatabaseExt};
212 use hir_def::{db::DefDatabase, AssocItemId, ModuleDefId};
213 use hir_expand::{
214 db::AstDatabase,
215 diagnostics::{Diagnostic, DiagnosticSinkBuilder},
216 };
217 use rustc_hash::FxHashMap;
218 use syntax::{TextRange, TextSize};
219
220 use crate::{diagnostics::validate_body, test_db::TestDB};
221
222 impl TestDB {
223 fn diagnostics<F: FnMut(&dyn Diagnostic)>(&self, mut cb: F) {
224 let crate_graph = self.crate_graph();
225 for krate in crate_graph.iter() {
226 let crate_def_map = self.crate_def_map(krate);
227
228 let mut fns = Vec::new();
229 for (module_id, _) in crate_def_map.modules.iter() {
230 for decl in crate_def_map[module_id].scope.declarations() {
231 if let ModuleDefId::FunctionId(f) = decl {
232 fns.push(f)
233 }
234 }
235
236 for impl_id in crate_def_map[module_id].scope.impls() {
237 let impl_data = self.impl_data(impl_id);
238 for item in impl_data.items.iter() {
239 if let AssocItemId::FunctionId(f) = item {
240 fns.push(*f)
241 }
242 }
243 }
244 }
245
246 for f in fns {
247 let mut sink = DiagnosticSinkBuilder::new().build(&mut cb);
248 validate_body(self, f.into(), &mut sink);
249 }
250 }
251 }
252 }
253
254 pub(crate) fn check_diagnostics(ra_fixture: &str) {
255 let db = TestDB::with_files(ra_fixture);
256 let annotations = db.extract_annotations();
257
258 let mut actual: FxHashMap<FileId, Vec<(TextRange, String)>> = FxHashMap::default();
259 db.diagnostics(|d| {
260 let src = d.display_source();
261 let root = db.parse_or_expand(src.file_id).unwrap();
262 // FIXME: macros...
263 let file_id = src.file_id.original_file(&db);
264 let range = src.value.to_node(&root).text_range();
265 let message = d.message().to_owned();
266 actual.entry(file_id).or_default().push((range, message));
267 });
268
269 for (file_id, diags) in actual.iter_mut() {
270 diags.sort_by_key(|it| it.0.start());
271 let text = db.file_text(*file_id);
272 // For multiline spans, place them on line start
273 for (range, content) in diags {
274 if text[*range].contains('\n') {
275 *range = TextRange::new(range.start(), range.start() + TextSize::from(1));
276 *content = format!("... {}", content);
277 }
278 }
279 }
280
281 assert_eq!(annotations, actual);
282 }
283
284 #[test]
285 fn no_such_field_diagnostics() {
286 check_diagnostics(
287 r#"
288struct S { foo: i32, bar: () }
289impl S {
290 fn new() -> S {
291 S {
292 //^ Missing structure fields:
293 //| - bar
294 foo: 92,
295 baz: 62,
296 //^^^^^^^ no such field
297 }
298 }
299}
300"#,
301 );
302 }
303 #[test]
304 fn no_such_field_with_feature_flag_diagnostics() {
305 check_diagnostics(
306 r#"
307//- /lib.rs crate:foo cfg:feature=foo
308struct MyStruct {
309 my_val: usize,
310 #[cfg(feature = "foo")]
311 bar: bool,
312}
313
314impl MyStruct {
315 #[cfg(feature = "foo")]
316 pub(crate) fn new(my_val: usize, bar: bool) -> Self {
317 Self { my_val, bar }
318 }
319 #[cfg(not(feature = "foo"))]
320 pub(crate) fn new(my_val: usize, _bar: bool) -> Self {
321 Self { my_val }
322 }
323}
324"#,
325 );
326 }
327
328 #[test]
329 fn no_such_field_enum_with_feature_flag_diagnostics() {
330 check_diagnostics(
331 r#"
332//- /lib.rs crate:foo cfg:feature=foo
333enum Foo {
334 #[cfg(not(feature = "foo"))]
335 Buz,
336 #[cfg(feature = "foo")]
337 Bar,
338 Baz
339}
340
341fn test_fn(f: Foo) {
342 match f {
343 Foo::Bar => {},
344 Foo::Baz => {},
345 }
346}
347"#,
348 );
349 }
350
351 #[test]
352 fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
353 check_diagnostics(
354 r#"
355//- /lib.rs crate:foo cfg:feature=foo
356struct S {
357 #[cfg(feature = "foo")]
358 foo: u32,
359 #[cfg(not(feature = "foo"))]
360 bar: u32,
361}
362
363impl S {
364 #[cfg(feature = "foo")]
365 fn new(foo: u32) -> Self {
366 Self { foo }
367 }
368 #[cfg(not(feature = "foo"))]
369 fn new(bar: u32) -> Self {
370 Self { bar }
371 }
372 fn new2(bar: u32) -> Self {
373 #[cfg(feature = "foo")]
374 { Self { foo: bar } }
375 #[cfg(not(feature = "foo"))]
376 { Self { bar } }
377 }
378 fn new2(val: u32) -> Self {
379 Self {
380 #[cfg(feature = "foo")]
381 foo: val,
382 #[cfg(not(feature = "foo"))]
383 bar: val,
384 }
385 }
386}
387"#,
388 );
389 }
390
391 #[test]
392 fn no_such_field_with_type_macro() {
393 check_diagnostics(
394 r#"
395macro_rules! Type { () => { u32 }; }
396struct Foo { bar: Type![] }
397
398impl Foo {
399 fn new() -> Self {
400 Foo { bar: 0 }
401 }
402}
403"#,
404 );
405 }
406
407 #[test]
408 fn missing_record_pat_field_diagnostic() {
409 check_diagnostics(
410 r#"
411struct S { foo: i32, bar: () }
412fn baz(s: S) {
413 let S { foo: _ } = s;
414 //^ Missing structure fields:
415 //| - bar
416}
417"#,
418 );
419 }
420
421 #[test]
422 fn missing_record_pat_field_no_diagnostic_if_not_exhaustive() {
423 check_diagnostics(
424 r"
425struct S { foo: i32, bar: () }
426fn baz(s: S) -> i32 {
427 match s {
428 S { foo, .. } => foo,
429 }
430}
431",
432 )
433 }
434
435 #[test]
436 fn break_outside_of_loop() {
437 check_diagnostics(
438 r#"
439fn foo() { break; }
440 //^^^^^ break outside of loop
441"#,
442 );
443 }
444}
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
new file mode 100644
index 000000000..fb76e2e4e
--- /dev/null
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -0,0 +1,569 @@
1//! FIXME: write short doc here
2
3use std::sync::Arc;
4
5use hir_def::{path::path, resolver::HasResolver, AdtId, DefWithBodyId};
6use hir_expand::diagnostics::DiagnosticSink;
7use rustc_hash::FxHashSet;
8use syntax::{ast, AstPtr};
9
10use crate::{
11 db::HirDatabase,
12 diagnostics::{
13 match_check::{is_useful, MatchCheckCtx, Matrix, PatStack, Usefulness},
14 MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkInTailExpr, MissingPatFields,
15 },
16 utils::variant_data,
17 ApplicationTy, InferenceResult, Ty, TypeCtor,
18};
19
20pub use hir_def::{
21 body::{
22 scope::{ExprScopes, ScopeEntry, ScopeId},
23 Body, BodySourceMap, ExprPtr, ExprSource, PatPtr, PatSource,
24 },
25 expr::{
26 ArithOp, Array, BinaryOp, BindingAnnotation, CmpOp, Expr, ExprId, Literal, LogicOp,
27 MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField, Statement, UnaryOp,
28 },
29 src::HasSource,
30 LocalFieldId, Lookup, VariantId,
31};
32
33pub(super) struct ExprValidator<'a, 'b: 'a> {
34 owner: DefWithBodyId,
35 infer: Arc<InferenceResult>,
36 sink: &'a mut DiagnosticSink<'b>,
37}
38
39impl<'a, 'b> ExprValidator<'a, 'b> {
40 pub(super) fn new(
41 owner: DefWithBodyId,
42 infer: Arc<InferenceResult>,
43 sink: &'a mut DiagnosticSink<'b>,
44 ) -> ExprValidator<'a, 'b> {
45 ExprValidator { owner, infer, sink }
46 }
47
48 pub(super) fn validate_body(&mut self, db: &dyn HirDatabase) {
49 let body = db.body(self.owner.into());
50
51 for (id, expr) in body.exprs.iter() {
52 if let Some((variant_def, missed_fields, true)) =
53 record_literal_missing_fields(db, &self.infer, id, expr)
54 {
55 self.create_record_literal_missing_fields_diagnostic(
56 id,
57 db,
58 variant_def,
59 missed_fields,
60 );
61 }
62
63 match expr {
64 Expr::Match { expr, arms } => {
65 self.validate_match(id, *expr, arms, db, self.infer.clone());
66 }
67 Expr::Call { .. } | Expr::MethodCall { .. } => {
68 self.validate_call(db, id, expr);
69 }
70 _ => {}
71 }
72 }
73 for (id, pat) in body.pats.iter() {
74 if let Some((variant_def, missed_fields, true)) =
75 record_pattern_missing_fields(db, &self.infer, id, pat)
76 {
77 self.create_record_pattern_missing_fields_diagnostic(
78 id,
79 db,
80 variant_def,
81 missed_fields,
82 );
83 }
84 }
85 let body_expr = &body[body.body_expr];
86 if let Expr::Block { tail: Some(t), .. } = body_expr {
87 self.validate_results_in_tail_expr(body.body_expr, *t, db);
88 }
89 }
90
91 fn create_record_literal_missing_fields_diagnostic(
92 &mut self,
93 id: ExprId,
94 db: &dyn HirDatabase,
95 variant_def: VariantId,
96 missed_fields: Vec<LocalFieldId>,
97 ) {
98 // XXX: only look at source_map if we do have missing fields
99 let (_, source_map) = db.body_with_source_map(self.owner.into());
100
101 if let Ok(source_ptr) = source_map.expr_syntax(id) {
102 let root = source_ptr.file_syntax(db.upcast());
103 if let ast::Expr::RecordExpr(record_expr) = &source_ptr.value.to_node(&root) {
104 if let Some(_) = record_expr.record_expr_field_list() {
105 let variant_data = variant_data(db.upcast(), variant_def);
106 let missed_fields = missed_fields
107 .into_iter()
108 .map(|idx| variant_data.fields()[idx].name.clone())
109 .collect();
110 self.sink.push(MissingFields {
111 file: source_ptr.file_id,
112 field_list_parent: AstPtr::new(&record_expr),
113 field_list_parent_path: record_expr.path().map(|path| AstPtr::new(&path)),
114 missed_fields,
115 })
116 }
117 }
118 }
119 }
120
121 fn create_record_pattern_missing_fields_diagnostic(
122 &mut self,
123 id: PatId,
124 db: &dyn HirDatabase,
125 variant_def: VariantId,
126 missed_fields: Vec<LocalFieldId>,
127 ) {
128 // XXX: only look at source_map if we do have missing fields
129 let (_, source_map) = db.body_with_source_map(self.owner.into());
130
131 if let Ok(source_ptr) = source_map.pat_syntax(id) {
132 if let Some(expr) = source_ptr.value.as_ref().left() {
133 let root = source_ptr.file_syntax(db.upcast());
134 if let ast::Pat::RecordPat(record_pat) = expr.to_node(&root) {
135 if let Some(_) = record_pat.record_pat_field_list() {
136 let variant_data = variant_data(db.upcast(), variant_def);
137 let missed_fields = missed_fields
138 .into_iter()
139 .map(|idx| variant_data.fields()[idx].name.clone())
140 .collect();
141 self.sink.push(MissingPatFields {
142 file: source_ptr.file_id,
143 field_list_parent: AstPtr::new(&record_pat),
144 field_list_parent_path: record_pat
145 .path()
146 .map(|path| AstPtr::new(&path)),
147 missed_fields,
148 })
149 }
150 }
151 }
152 }
153 }
154
155 fn validate_call(&mut self, db: &dyn HirDatabase, call_id: ExprId, expr: &Expr) -> Option<()> {
156 // Check that the number of arguments matches the number of parameters.
157
158 // FIXME: Due to shortcomings in the current type system implementation, only emit this
159 // diagnostic if there are no type mismatches in the containing function.
160 if self.infer.type_mismatches.iter().next().is_some() {
161 return Some(());
162 }
163
164 let is_method_call = matches!(expr, Expr::MethodCall { .. });
165 let (sig, args) = match expr {
166 Expr::Call { callee, args } => {
167 let callee = &self.infer.type_of_expr[*callee];
168 let sig = callee.callable_sig(db)?;
169 (sig, args.clone())
170 }
171 Expr::MethodCall { receiver, args, .. } => {
172 let mut args = args.clone();
173 args.insert(0, *receiver);
174
175 // FIXME: note that we erase information about substs here. This
176 // is not right, but, luckily, doesn't matter as we care only
177 // about the number of params
178 let callee = self.infer.method_resolution(call_id)?;
179 let sig = db.callable_item_signature(callee.into()).value;
180
181 (sig, args)
182 }
183 _ => return None,
184 };
185
186 if sig.is_varargs {
187 return None;
188 }
189
190 let params = sig.params();
191
192 let mut param_count = params.len();
193 let mut arg_count = args.len();
194
195 if arg_count != param_count {
196 let (_, source_map) = db.body_with_source_map(self.owner.into());
197 if let Ok(source_ptr) = source_map.expr_syntax(call_id) {
198 if is_method_call {
199 param_count -= 1;
200 arg_count -= 1;
201 }
202 self.sink.push(MismatchedArgCount {
203 file: source_ptr.file_id,
204 call_expr: source_ptr.value,
205 expected: param_count,
206 found: arg_count,
207 });
208 }
209 }
210
211 None
212 }
213
214 fn validate_match(
215 &mut self,
216 id: ExprId,
217 match_expr: ExprId,
218 arms: &[MatchArm],
219 db: &dyn HirDatabase,
220 infer: Arc<InferenceResult>,
221 ) {
222 let (body, source_map): (Arc<Body>, Arc<BodySourceMap>) =
223 db.body_with_source_map(self.owner.into());
224
225 let match_expr_ty = match infer.type_of_expr.get(match_expr) {
226 Some(ty) => ty,
227 // If we can't resolve the type of the match expression
228 // we cannot perform exhaustiveness checks.
229 None => return,
230 };
231
232 let cx = MatchCheckCtx { match_expr, body, infer: infer.clone(), db };
233 let pats = arms.iter().map(|arm| arm.pat);
234
235 let mut seen = Matrix::empty();
236 for pat in pats {
237 if let Some(pat_ty) = infer.type_of_pat.get(pat) {
238 // We only include patterns whose type matches the type
239 // of the match expression. If we had a InvalidMatchArmPattern
240 // diagnostic or similar we could raise that in an else
241 // block here.
242 //
243 // When comparing the types, we also have to consider that rustc
244 // will automatically de-reference the match expression type if
245 // necessary.
246 //
247 // FIXME we should use the type checker for this.
248 if pat_ty == match_expr_ty
249 || match_expr_ty
250 .as_reference()
251 .map(|(match_expr_ty, _)| match_expr_ty == pat_ty)
252 .unwrap_or(false)
253 {
254 // If we had a NotUsefulMatchArm diagnostic, we could
255 // check the usefulness of each pattern as we added it
256 // to the matrix here.
257 let v = PatStack::from_pattern(pat);
258 seen.push(&cx, v);
259 continue;
260 }
261 }
262
263 // If we can't resolve the type of a pattern, or the pattern type doesn't
264 // fit the match expression, we skip this diagnostic. Skipping the entire
265 // diagnostic rather than just not including this match arm is preferred
266 // to avoid the chance of false positives.
267 return;
268 }
269
270 match is_useful(&cx, &seen, &PatStack::from_wild()) {
271 Ok(Usefulness::Useful) => (),
272 // if a wildcard pattern is not useful, then all patterns are covered
273 Ok(Usefulness::NotUseful) => return,
274 // this path is for unimplemented checks, so we err on the side of not
275 // reporting any errors
276 _ => return,
277 }
278
279 if let Ok(source_ptr) = source_map.expr_syntax(id) {
280 let root = source_ptr.file_syntax(db.upcast());
281 if let ast::Expr::MatchExpr(match_expr) = &source_ptr.value.to_node(&root) {
282 if let (Some(match_expr), Some(arms)) =
283 (match_expr.expr(), match_expr.match_arm_list())
284 {
285 self.sink.push(MissingMatchArms {
286 file: source_ptr.file_id,
287 match_expr: AstPtr::new(&match_expr),
288 arms: AstPtr::new(&arms),
289 })
290 }
291 }
292 }
293 }
294
295 fn validate_results_in_tail_expr(&mut self, body_id: ExprId, id: ExprId, db: &dyn HirDatabase) {
296 // the mismatch will be on the whole block currently
297 let mismatch = match self.infer.type_mismatch_for_expr(body_id) {
298 Some(m) => m,
299 None => return,
300 };
301
302 let core_result_path = path![core::result::Result];
303
304 let resolver = self.owner.resolver(db.upcast());
305 let core_result_enum = match resolver.resolve_known_enum(db.upcast(), &core_result_path) {
306 Some(it) => it,
307 _ => return,
308 };
309
310 let core_result_ctor = TypeCtor::Adt(AdtId::EnumId(core_result_enum));
311 let params = match &mismatch.expected {
312 Ty::Apply(ApplicationTy { ctor, parameters }) if ctor == &core_result_ctor => {
313 parameters
314 }
315 _ => return,
316 };
317
318 if params.len() == 2 && params[0] == mismatch.actual {
319 let (_, source_map) = db.body_with_source_map(self.owner.into());
320
321 if let Ok(source_ptr) = source_map.expr_syntax(id) {
322 self.sink
323 .push(MissingOkInTailExpr { file: source_ptr.file_id, expr: source_ptr.value });
324 }
325 }
326 }
327}
328
329pub fn record_literal_missing_fields(
330 db: &dyn HirDatabase,
331 infer: &InferenceResult,
332 id: ExprId,
333 expr: &Expr,
334) -> Option<(VariantId, Vec<LocalFieldId>, /*exhaustive*/ bool)> {
335 let (fields, exhausitve) = match expr {
336 Expr::RecordLit { path: _, fields, spread } => (fields, spread.is_none()),
337 _ => return None,
338 };
339
340 let variant_def = infer.variant_resolution_for_expr(id)?;
341 if let VariantId::UnionId(_) = variant_def {
342 return None;
343 }
344
345 let variant_data = variant_data(db.upcast(), variant_def);
346
347 let specified_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
348 let missed_fields: Vec<LocalFieldId> = variant_data
349 .fields()
350 .iter()
351 .filter_map(|(f, d)| if specified_fields.contains(&d.name) { None } else { Some(f) })
352 .collect();
353 if missed_fields.is_empty() {
354 return None;
355 }
356 Some((variant_def, missed_fields, exhausitve))
357}
358
359pub fn record_pattern_missing_fields(
360 db: &dyn HirDatabase,
361 infer: &InferenceResult,
362 id: PatId,
363 pat: &Pat,
364) -> Option<(VariantId, Vec<LocalFieldId>, /*exhaustive*/ bool)> {
365 let (fields, exhaustive) = match pat {
366 Pat::Record { path: _, args, ellipsis } => (args, !ellipsis),
367 _ => return None,
368 };
369
370 let variant_def = infer.variant_resolution_for_pat(id)?;
371 if let VariantId::UnionId(_) = variant_def {
372 return None;
373 }
374
375 let variant_data = variant_data(db.upcast(), variant_def);
376
377 let specified_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
378 let missed_fields: Vec<LocalFieldId> = variant_data
379 .fields()
380 .iter()
381 .filter_map(|(f, d)| if specified_fields.contains(&d.name) { None } else { Some(f) })
382 .collect();
383 if missed_fields.is_empty() {
384 return None;
385 }
386 Some((variant_def, missed_fields, exhaustive))
387}
388
389#[cfg(test)]
390mod tests {
391 use crate::diagnostics::tests::check_diagnostics;
392
393 #[test]
394 fn simple_free_fn_zero() {
395 check_diagnostics(
396 r#"
397fn zero() {}
398fn f() { zero(1); }
399 //^^^^^^^ Expected 0 arguments, found 1
400"#,
401 );
402
403 check_diagnostics(
404 r#"
405fn zero() {}
406fn f() { zero(); }
407"#,
408 );
409 }
410
411 #[test]
412 fn simple_free_fn_one() {
413 check_diagnostics(
414 r#"
415fn one(arg: u8) {}
416fn f() { one(); }
417 //^^^^^ Expected 1 argument, found 0
418"#,
419 );
420
421 check_diagnostics(
422 r#"
423fn one(arg: u8) {}
424fn f() { one(1); }
425"#,
426 );
427 }
428
429 #[test]
430 fn method_as_fn() {
431 check_diagnostics(
432 r#"
433struct S;
434impl S { fn method(&self) {} }
435
436fn f() {
437 S::method();
438} //^^^^^^^^^^^ Expected 1 argument, found 0
439"#,
440 );
441
442 check_diagnostics(
443 r#"
444struct S;
445impl S { fn method(&self) {} }
446
447fn f() {
448 S::method(&S);
449 S.method();
450}
451"#,
452 );
453 }
454
455 #[test]
456 fn method_with_arg() {
457 check_diagnostics(
458 r#"
459struct S;
460impl S { fn method(&self, arg: u8) {} }
461
462 fn f() {
463 S.method();
464 } //^^^^^^^^^^ Expected 1 argument, found 0
465 "#,
466 );
467
468 check_diagnostics(
469 r#"
470struct S;
471impl S { fn method(&self, arg: u8) {} }
472
473fn f() {
474 S::method(&S, 0);
475 S.method(1);
476}
477"#,
478 );
479 }
480
481 #[test]
482 fn tuple_struct() {
483 check_diagnostics(
484 r#"
485struct Tup(u8, u16);
486fn f() {
487 Tup(0);
488} //^^^^^^ Expected 2 arguments, found 1
489"#,
490 )
491 }
492
493 #[test]
494 fn enum_variant() {
495 check_diagnostics(
496 r#"
497enum En { Variant(u8, u16), }
498fn f() {
499 En::Variant(0);
500} //^^^^^^^^^^^^^^ Expected 2 arguments, found 1
501"#,
502 )
503 }
504
505 #[test]
506 fn enum_variant_type_macro() {
507 check_diagnostics(
508 r#"
509macro_rules! Type {
510 () => { u32 };
511}
512enum Foo {
513 Bar(Type![])
514}
515impl Foo {
516 fn new() {
517 Foo::Bar(0);
518 Foo::Bar(0, 1);
519 //^^^^^^^^^^^^^^ Expected 1 argument, found 2
520 Foo::Bar();
521 //^^^^^^^^^^ Expected 1 argument, found 0
522 }
523}
524 "#,
525 );
526 }
527
528 #[test]
529 fn varargs() {
530 check_diagnostics(
531 r#"
532extern "C" {
533 fn fixed(fixed: u8);
534 fn varargs(fixed: u8, ...);
535 fn varargs2(...);
536}
537
538fn f() {
539 unsafe {
540 fixed(0);
541 fixed(0, 1);
542 //^^^^^^^^^^^ Expected 1 argument, found 2
543 varargs(0);
544 varargs(0, 1);
545 varargs2();
546 varargs2(0);
547 varargs2(0, 1);
548 }
549}
550 "#,
551 )
552 }
553
554 #[test]
555 fn arg_count_lambda() {
556 check_diagnostics(
557 r#"
558fn main() {
559 let f = |()| ();
560 f();
561 //^^^ Expected 1 argument, found 0
562 f(());
563 f((), ());
564 //^^^^^^^^^ Expected 1 argument, found 2
565}
566"#,
567 )
568 }
569}
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
new file mode 100644
index 000000000..7f007f1d6
--- /dev/null
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -0,0 +1,1421 @@
1//! This module implements match statement exhaustiveness checking and usefulness checking
2//! for match arms.
3//!
4//! It is modeled on the rustc module `librustc_mir_build::hair::pattern::_match`, which
5//! contains very detailed documentation about the algorithms used here. I've duplicated
6//! most of that documentation below.
7//!
8//! This file includes the logic for exhaustiveness and usefulness checking for
9//! pattern-matching. Specifically, given a list of patterns for a type, we can
10//! tell whether:
11//! - (a) the patterns cover every possible constructor for the type (exhaustiveness).
12//! - (b) each pattern is necessary (usefulness).
13//!
14//! The algorithm implemented here is a modified version of the one described in
15//! <http://moscova.inria.fr/~maranget/papers/warn/index.html>.
16//! However, to save future implementors from reading the original paper, we
17//! summarise the algorithm here to hopefully save time and be a little clearer
18//! (without being so rigorous).
19//!
20//! The core of the algorithm revolves about a "usefulness" check. In particular, we
21//! are trying to compute a predicate `U(P, p)` where `P` is a list of patterns (we refer to this as
22//! a matrix). `U(P, p)` represents whether, given an existing list of patterns
23//! `P_1 ..= P_m`, adding a new pattern `p` will be "useful" (that is, cover previously-
24//! uncovered values of the type).
25//!
26//! If we have this predicate, then we can easily compute both exhaustiveness of an
27//! entire set of patterns and the individual usefulness of each one.
28//! (a) the set of patterns is exhaustive iff `U(P, _)` is false (i.e., adding a wildcard
29//! match doesn't increase the number of values we're matching)
30//! (b) a pattern `P_i` is not useful if `U(P[0..=(i-1), P_i)` is false (i.e., adding a
31//! pattern to those that have come before it doesn't increase the number of values
32//! we're matching).
33//!
34//! During the course of the algorithm, the rows of the matrix won't just be individual patterns,
35//! but rather partially-deconstructed patterns in the form of a list of patterns. The paper
36//! calls those pattern-vectors, and we will call them pattern-stacks. The same holds for the
37//! new pattern `p`.
38//!
39//! For example, say we have the following:
40//!
41//! ```ignore
42//! // x: (Option<bool>, Result<()>)
43//! match x {
44//! (Some(true), _) => (),
45//! (None, Err(())) => (),
46//! (None, Err(_)) => (),
47//! }
48//! ```
49//!
50//! Here, the matrix `P` starts as:
51//!
52//! ```text
53//! [
54//! [(Some(true), _)],
55//! [(None, Err(()))],
56//! [(None, Err(_))],
57//! ]
58//! ```
59//!
60//! We can tell it's not exhaustive, because `U(P, _)` is true (we're not covering
61//! `[(Some(false), _)]`, for instance). In addition, row 3 is not useful, because
62//! all the values it covers are already covered by row 2.
63//!
64//! A list of patterns can be thought of as a stack, because we are mainly interested in the top of
65//! the stack at any given point, and we can pop or apply constructors to get new pattern-stacks.
66//! To match the paper, the top of the stack is at the beginning / on the left.
67//!
68//! There are two important operations on pattern-stacks necessary to understand the algorithm:
69//!
70//! 1. We can pop a given constructor off the top of a stack. This operation is called
71//! `specialize`, and is denoted `S(c, p)` where `c` is a constructor (like `Some` or
72//! `None`) and `p` a pattern-stack.
73//! If the pattern on top of the stack can cover `c`, this removes the constructor and
74//! pushes its arguments onto the stack. It also expands OR-patterns into distinct patterns.
75//! Otherwise the pattern-stack is discarded.
76//! This essentially filters those pattern-stacks whose top covers the constructor `c` and
77//! discards the others.
78//!
79//! For example, the first pattern above initially gives a stack `[(Some(true), _)]`. If we
80//! pop the tuple constructor, we are left with `[Some(true), _]`, and if we then pop the
81//! `Some` constructor we get `[true, _]`. If we had popped `None` instead, we would get
82//! nothing back.
83//!
84//! This returns zero or more new pattern-stacks, as follows. We look at the pattern `p_1`
85//! on top of the stack, and we have four cases:
86//!
87//! * 1.1. `p_1 = c(r_1, .., r_a)`, i.e. the top of the stack has constructor `c`. We push onto
88//! the stack the arguments of this constructor, and return the result:
89//!
90//! r_1, .., r_a, p_2, .., p_n
91//!
92//! * 1.2. `p_1 = c'(r_1, .., r_a')` where `c ≠ c'`. We discard the current stack and return
93//! nothing.
94//! * 1.3. `p_1 = _`. We push onto the stack as many wildcards as the constructor `c` has
95//! arguments (its arity), and return the resulting stack:
96//!
97//! _, .., _, p_2, .., p_n
98//!
99//! * 1.4. `p_1 = r_1 | r_2`. We expand the OR-pattern and then recurse on each resulting stack:
100//!
101//! S(c, (r_1, p_2, .., p_n))
102//! S(c, (r_2, p_2, .., p_n))
103//!
104//! 2. We can pop a wildcard off the top of the stack. This is called `D(p)`, where `p` is
105//! a pattern-stack.
106//! This is used when we know there are missing constructor cases, but there might be
107//! existing wildcard patterns, so to check the usefulness of the matrix, we have to check
108//! all its *other* components.
109//!
110//! It is computed as follows. We look at the pattern `p_1` on top of the stack,
111//! and we have three cases:
112//! * 1.1. `p_1 = c(r_1, .., r_a)`. We discard the current stack and return nothing.
113//! * 1.2. `p_1 = _`. We return the rest of the stack:
114//!
115//! p_2, .., p_n
116//!
117//! * 1.3. `p_1 = r_1 | r_2`. We expand the OR-pattern and then recurse on each resulting stack:
118//!
119//! D((r_1, p_2, .., p_n))
120//! D((r_2, p_2, .., p_n))
121//!
122//! Note that the OR-patterns are not always used directly in Rust, but are used to derive the
123//! exhaustive integer matching rules, so they're written here for posterity.
124//!
125//! Both those operations extend straightforwardly to a list or pattern-stacks, i.e. a matrix, by
126//! working row-by-row. Popping a constructor ends up keeping only the matrix rows that start with
127//! the given constructor, and popping a wildcard keeps those rows that start with a wildcard.
128//!
129//!
130//! The algorithm for computing `U`
131//! -------------------------------
132//! The algorithm is inductive (on the number of columns: i.e., components of tuple patterns).
133//! That means we're going to check the components from left-to-right, so the algorithm
134//! operates principally on the first component of the matrix and new pattern-stack `p`.
135//! This algorithm is realised in the `is_useful` function.
136//!
137//! Base case (`n = 0`, i.e., an empty tuple pattern):
138//! - If `P` already contains an empty pattern (i.e., if the number of patterns `m > 0`), then
139//! `U(P, p)` is false.
140//! - Otherwise, `P` must be empty, so `U(P, p)` is true.
141//!
142//! Inductive step (`n > 0`, i.e., whether there's at least one column [which may then be expanded
143//! into further columns later]). We're going to match on the top of the new pattern-stack, `p_1`:
144//!
145//! - If `p_1 == c(r_1, .., r_a)`, i.e. we have a constructor pattern.
146//! Then, the usefulness of `p_1` can be reduced to whether it is useful when
147//! we ignore all the patterns in the first column of `P` that involve other constructors.
148//! This is where `S(c, P)` comes in:
149//!
150//! ```text
151//! U(P, p) := U(S(c, P), S(c, p))
152//! ```
153//!
154//! This special case is handled in `is_useful_specialized`.
155//!
156//! For example, if `P` is:
157//!
158//! ```text
159//! [
160//! [Some(true), _],
161//! [None, 0],
162//! ]
163//! ```
164//!
165//! and `p` is `[Some(false), 0]`, then we don't care about row 2 since we know `p` only
166//! matches values that row 2 doesn't. For row 1 however, we need to dig into the
167//! arguments of `Some` to know whether some new value is covered. So we compute
168//! `U([[true, _]], [false, 0])`.
169//!
170//! - If `p_1 == _`, then we look at the list of constructors that appear in the first component of
171//! the rows of `P`:
172//! - If there are some constructors that aren't present, then we might think that the
173//! wildcard `_` is useful, since it covers those constructors that weren't covered
174//! before.
175//! That's almost correct, but only works if there were no wildcards in those first
176//! components. So we need to check that `p` is useful with respect to the rows that
177//! start with a wildcard, if there are any. This is where `D` comes in:
178//! `U(P, p) := U(D(P), D(p))`
179//!
180//! For example, if `P` is:
181//! ```text
182//! [
183//! [_, true, _],
184//! [None, false, 1],
185//! ]
186//! ```
187//! and `p` is `[_, false, _]`, the `Some` constructor doesn't appear in `P`. So if we
188//! only had row 2, we'd know that `p` is useful. However row 1 starts with a
189//! wildcard, so we need to check whether `U([[true, _]], [false, 1])`.
190//!
191//! - Otherwise, all possible constructors (for the relevant type) are present. In this
192//! case we must check whether the wildcard pattern covers any unmatched value. For
193//! that, we can think of the `_` pattern as a big OR-pattern that covers all
194//! possible constructors. For `Option`, that would mean `_ = None | Some(_)` for
195//! example. The wildcard pattern is useful in this case if it is useful when
196//! specialized to one of the possible constructors. So we compute:
197//! `U(P, p) := ∃(k ϵ constructors) U(S(k, P), S(k, p))`
198//!
199//! For example, if `P` is:
200//! ```text
201//! [
202//! [Some(true), _],
203//! [None, false],
204//! ]
205//! ```
206//! and `p` is `[_, false]`, both `None` and `Some` constructors appear in the first
207//! components of `P`. We will therefore try popping both constructors in turn: we
208//! compute `U([[true, _]], [_, false])` for the `Some` constructor, and `U([[false]],
209//! [false])` for the `None` constructor. The first case returns true, so we know that
210//! `p` is useful for `P`. Indeed, it matches `[Some(false), _]` that wasn't matched
211//! before.
212//!
213//! - If `p_1 == r_1 | r_2`, then the usefulness depends on each `r_i` separately:
214//!
215//! ```text
216//! U(P, p) := U(P, (r_1, p_2, .., p_n))
217//! || U(P, (r_2, p_2, .., p_n))
218//! ```
219use std::sync::Arc;
220
221use arena::Idx;
222use hir_def::{
223 adt::VariantData,
224 body::Body,
225 expr::{Expr, Literal, Pat, PatId},
226 AdtId, EnumVariantId, VariantId,
227};
228use smallvec::{smallvec, SmallVec};
229
230use crate::{db::HirDatabase, ApplicationTy, InferenceResult, Ty, TypeCtor};
231
232#[derive(Debug, Clone, Copy)]
233/// Either a pattern from the source code being analyzed, represented as
234/// as `PatId`, or a `Wild` pattern which is created as an intermediate
235/// step in the match checking algorithm and thus is not backed by a
236/// real `PatId`.
237///
238/// Note that it is totally valid for the `PatId` variant to contain
239/// a `PatId` which resolves to a `Wild` pattern, if that wild pattern
240/// exists in the source code being analyzed.
241enum PatIdOrWild {
242 PatId(PatId),
243 Wild,
244}
245
246impl PatIdOrWild {
247 fn as_pat(self, cx: &MatchCheckCtx) -> Pat {
248 match self {
249 PatIdOrWild::PatId(id) => cx.body.pats[id].clone(),
250 PatIdOrWild::Wild => Pat::Wild,
251 }
252 }
253
254 fn as_id(self) -> Option<PatId> {
255 match self {
256 PatIdOrWild::PatId(id) => Some(id),
257 PatIdOrWild::Wild => None,
258 }
259 }
260}
261
262impl From<PatId> for PatIdOrWild {
263 fn from(pat_id: PatId) -> Self {
264 Self::PatId(pat_id)
265 }
266}
267
268impl From<&PatId> for PatIdOrWild {
269 fn from(pat_id: &PatId) -> Self {
270 Self::PatId(*pat_id)
271 }
272}
273
274#[derive(Debug, Clone, Copy, PartialEq)]
275pub(super) enum MatchCheckErr {
276 NotImplemented,
277 MalformedMatchArm,
278 /// Used when type inference cannot resolve the type of
279 /// a pattern or expression.
280 Unknown,
281}
282
283/// The return type of `is_useful` is either an indication of usefulness
284/// of the match arm, or an error in the case the match statement
285/// is made up of types for which exhaustiveness checking is currently
286/// not completely implemented.
287///
288/// The `std::result::Result` type is used here rather than a custom enum
289/// to allow the use of `?`.
290pub(super) type MatchCheckResult<T> = Result<T, MatchCheckErr>;
291
292#[derive(Debug)]
293/// A row in a Matrix.
294///
295/// This type is modeled from the struct of the same name in `rustc`.
296pub(super) struct PatStack(PatStackInner);
297type PatStackInner = SmallVec<[PatIdOrWild; 2]>;
298
299impl PatStack {
300 pub(super) fn from_pattern(pat_id: PatId) -> PatStack {
301 Self(smallvec!(pat_id.into()))
302 }
303
304 pub(super) fn from_wild() -> PatStack {
305 Self(smallvec!(PatIdOrWild::Wild))
306 }
307
308 fn from_slice(slice: &[PatIdOrWild]) -> PatStack {
309 Self(SmallVec::from_slice(slice))
310 }
311
312 fn from_vec(v: PatStackInner) -> PatStack {
313 Self(v)
314 }
315
316 fn get_head(&self) -> Option<PatIdOrWild> {
317 self.0.first().copied()
318 }
319
320 fn tail(&self) -> &[PatIdOrWild] {
321 self.0.get(1..).unwrap_or(&[])
322 }
323
324 fn to_tail(&self) -> PatStack {
325 Self::from_slice(self.tail())
326 }
327
328 fn replace_head_with<I, T>(&self, pats: I) -> PatStack
329 where
330 I: Iterator<Item = T>,
331 T: Into<PatIdOrWild>,
332 {
333 let mut patterns: PatStackInner = smallvec![];
334 for pat in pats {
335 patterns.push(pat.into());
336 }
337 for pat in &self.0[1..] {
338 patterns.push(*pat);
339 }
340 PatStack::from_vec(patterns)
341 }
342
343 /// Computes `D(self)`.
344 ///
345 /// See the module docs and the associated documentation in rustc for details.
346 fn specialize_wildcard(&self, cx: &MatchCheckCtx) -> Option<PatStack> {
347 if matches!(self.get_head()?.as_pat(cx), Pat::Wild) {
348 Some(self.to_tail())
349 } else {
350 None
351 }
352 }
353
354 /// Computes `S(constructor, self)`.
355 ///
356 /// See the module docs and the associated documentation in rustc for details.
357 fn specialize_constructor(
358 &self,
359 cx: &MatchCheckCtx,
360 constructor: &Constructor,
361 ) -> MatchCheckResult<Option<PatStack>> {
362 let head = match self.get_head() {
363 Some(head) => head,
364 None => return Ok(None),
365 };
366
367 let head_pat = head.as_pat(cx);
368 let result = match (head_pat, constructor) {
369 (Pat::Tuple { args: ref pat_ids, ellipsis }, Constructor::Tuple { arity: _ }) => {
370 if ellipsis.is_some() {
371 // If there are ellipsis here, we should add the correct number of
372 // Pat::Wild patterns to `pat_ids`. We should be able to use the
373 // constructors arity for this, but at the time of writing we aren't
374 // correctly calculating this arity when ellipsis are present.
375 return Err(MatchCheckErr::NotImplemented);
376 }
377
378 Some(self.replace_head_with(pat_ids.iter()))
379 }
380 (Pat::Lit(lit_expr), Constructor::Bool(constructor_val)) => {
381 match cx.body.exprs[lit_expr] {
382 Expr::Literal(Literal::Bool(pat_val)) if *constructor_val == pat_val => {
383 Some(self.to_tail())
384 }
385 // it was a bool but the value doesn't match
386 Expr::Literal(Literal::Bool(_)) => None,
387 // perhaps this is actually unreachable given we have
388 // already checked that these match arms have the appropriate type?
389 _ => return Err(MatchCheckErr::NotImplemented),
390 }
391 }
392 (Pat::Wild, constructor) => Some(self.expand_wildcard(cx, constructor)?),
393 (Pat::Path(_), Constructor::Enum(constructor)) => {
394 // unit enum variants become `Pat::Path`
395 let pat_id = head.as_id().expect("we know this isn't a wild");
396 if !enum_variant_matches(cx, pat_id, *constructor) {
397 None
398 } else {
399 Some(self.to_tail())
400 }
401 }
402 (
403 Pat::TupleStruct { args: ref pat_ids, ellipsis, .. },
404 Constructor::Enum(enum_constructor),
405 ) => {
406 let pat_id = head.as_id().expect("we know this isn't a wild");
407 if !enum_variant_matches(cx, pat_id, *enum_constructor) {
408 None
409 } else {
410 let constructor_arity = constructor.arity(cx)?;
411 if let Some(ellipsis_position) = ellipsis {
412 // If there are ellipsis in the pattern, the ellipsis must take the place
413 // of at least one sub-pattern, so `pat_ids` should be smaller than the
414 // constructor arity.
415 if pat_ids.len() < constructor_arity {
416 let mut new_patterns: Vec<PatIdOrWild> = vec![];
417
418 for pat_id in &pat_ids[0..ellipsis_position] {
419 new_patterns.push((*pat_id).into());
420 }
421
422 for _ in 0..(constructor_arity - pat_ids.len()) {
423 new_patterns.push(PatIdOrWild::Wild);
424 }
425
426 for pat_id in &pat_ids[ellipsis_position..pat_ids.len()] {
427 new_patterns.push((*pat_id).into());
428 }
429
430 Some(self.replace_head_with(new_patterns.into_iter()))
431 } else {
432 return Err(MatchCheckErr::MalformedMatchArm);
433 }
434 } else {
435 // If there is no ellipsis in the tuple pattern, the number
436 // of patterns must equal the constructor arity.
437 if pat_ids.len() == constructor_arity {
438 Some(self.replace_head_with(pat_ids.into_iter()))
439 } else {
440 return Err(MatchCheckErr::MalformedMatchArm);
441 }
442 }
443 }
444 }
445 (Pat::Record { args: ref arg_patterns, .. }, Constructor::Enum(e)) => {
446 let pat_id = head.as_id().expect("we know this isn't a wild");
447 if !enum_variant_matches(cx, pat_id, *e) {
448 None
449 } else {
450 match cx.db.enum_data(e.parent).variants[e.local_id].variant_data.as_ref() {
451 VariantData::Record(struct_field_arena) => {
452 // Here we treat any missing fields in the record as the wild pattern, as
453 // if the record has ellipsis. We want to do this here even if the
454 // record does not contain ellipsis, because it allows us to continue
455 // enforcing exhaustiveness for the rest of the match statement.
456 //
457 // Creating the diagnostic for the missing field in the pattern
458 // should be done in a different diagnostic.
459 let patterns = struct_field_arena.iter().map(|(_, struct_field)| {
460 arg_patterns
461 .iter()
462 .find(|pat| pat.name == struct_field.name)
463 .map(|pat| PatIdOrWild::from(pat.pat))
464 .unwrap_or(PatIdOrWild::Wild)
465 });
466
467 Some(self.replace_head_with(patterns))
468 }
469 _ => return Err(MatchCheckErr::Unknown),
470 }
471 }
472 }
473 (Pat::Or(_), _) => return Err(MatchCheckErr::NotImplemented),
474 (_, _) => return Err(MatchCheckErr::NotImplemented),
475 };
476
477 Ok(result)
478 }
479
480 /// A special case of `specialize_constructor` where the head of the pattern stack
481 /// is a Wild pattern.
482 ///
483 /// Replaces the Wild pattern at the head of the pattern stack with N Wild patterns
484 /// (N >= 0), where N is the arity of the given constructor.
485 fn expand_wildcard(
486 &self,
487 cx: &MatchCheckCtx,
488 constructor: &Constructor,
489 ) -> MatchCheckResult<PatStack> {
490 assert_eq!(
491 Pat::Wild,
492 self.get_head().expect("expand_wildcard called on empty PatStack").as_pat(cx),
493 "expand_wildcard must only be called on PatStack with wild at head",
494 );
495
496 let mut patterns: PatStackInner = smallvec![];
497
498 for _ in 0..constructor.arity(cx)? {
499 patterns.push(PatIdOrWild::Wild);
500 }
501
502 for pat in &self.0[1..] {
503 patterns.push(*pat);
504 }
505
506 Ok(PatStack::from_vec(patterns))
507 }
508}
509
510/// A collection of PatStack.
511///
512/// This type is modeled from the struct of the same name in `rustc`.
513pub(super) struct Matrix(Vec<PatStack>);
514
515impl Matrix {
516 pub(super) fn empty() -> Self {
517 Self(vec![])
518 }
519
520 pub(super) fn push(&mut self, cx: &MatchCheckCtx, row: PatStack) {
521 if let Some(Pat::Or(pat_ids)) = row.get_head().map(|pat_id| pat_id.as_pat(cx)) {
522 // Or patterns are expanded here
523 for pat_id in pat_ids {
524 self.0.push(PatStack::from_pattern(pat_id));
525 }
526 } else {
527 self.0.push(row);
528 }
529 }
530
531 fn is_empty(&self) -> bool {
532 self.0.is_empty()
533 }
534
535 fn heads(&self) -> Vec<PatIdOrWild> {
536 self.0.iter().flat_map(|p| p.get_head()).collect()
537 }
538
539 /// Computes `D(self)` for each contained PatStack.
540 ///
541 /// See the module docs and the associated documentation in rustc for details.
542 fn specialize_wildcard(&self, cx: &MatchCheckCtx) -> Self {
543 Self::collect(cx, self.0.iter().filter_map(|r| r.specialize_wildcard(cx)))
544 }
545
546 /// Computes `S(constructor, self)` for each contained PatStack.
547 ///
548 /// See the module docs and the associated documentation in rustc for details.
549 fn specialize_constructor(
550 &self,
551 cx: &MatchCheckCtx,
552 constructor: &Constructor,
553 ) -> MatchCheckResult<Self> {
554 let mut new_matrix = Matrix::empty();
555 for pat in &self.0 {
556 if let Some(pat) = pat.specialize_constructor(cx, constructor)? {
557 new_matrix.push(cx, pat);
558 }
559 }
560
561 Ok(new_matrix)
562 }
563
564 fn collect<T: IntoIterator<Item = PatStack>>(cx: &MatchCheckCtx, iter: T) -> Self {
565 let mut matrix = Matrix::empty();
566
567 for pat in iter {
568 // using push ensures we expand or-patterns
569 matrix.push(cx, pat);
570 }
571
572 matrix
573 }
574}
575
576#[derive(Clone, Debug, PartialEq)]
577/// An indication of the usefulness of a given match arm, where
578/// usefulness is defined as matching some patterns which were
579/// not matched by an prior match arms.
580///
581/// We may eventually need an `Unknown` variant here.
582pub(super) enum Usefulness {
583 Useful,
584 NotUseful,
585}
586
587pub(super) struct MatchCheckCtx<'a> {
588 pub(super) match_expr: Idx<Expr>,
589 pub(super) body: Arc<Body>,
590 pub(super) infer: Arc<InferenceResult>,
591 pub(super) db: &'a dyn HirDatabase,
592}
593
594/// Given a set of patterns `matrix`, and pattern to consider `v`, determines
595/// whether `v` is useful. A pattern is useful if it covers cases which were
596/// not previously covered.
597///
598/// When calling this function externally (that is, not the recursive calls) it
599/// expected that you have already type checked the match arms. All patterns in
600/// matrix should be the same type as v, as well as they should all be the same
601/// type as the match expression.
602pub(super) fn is_useful(
603 cx: &MatchCheckCtx,
604 matrix: &Matrix,
605 v: &PatStack,
606) -> MatchCheckResult<Usefulness> {
607 // Handle two special cases:
608 // - enum with no variants
609 // - `!` type
610 // In those cases, no match arm is useful.
611 match cx.infer[cx.match_expr].strip_references() {
612 Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(AdtId::EnumId(enum_id)), .. }) => {
613 if cx.db.enum_data(*enum_id).variants.is_empty() {
614 return Ok(Usefulness::NotUseful);
615 }
616 }
617 Ty::Apply(ApplicationTy { ctor: TypeCtor::Never, .. }) => {
618 return Ok(Usefulness::NotUseful);
619 }
620 _ => (),
621 }
622
623 let head = match v.get_head() {
624 Some(head) => head,
625 None => {
626 let result = if matrix.is_empty() { Usefulness::Useful } else { Usefulness::NotUseful };
627
628 return Ok(result);
629 }
630 };
631
632 if let Pat::Or(pat_ids) = head.as_pat(cx) {
633 let mut found_unimplemented = false;
634 let any_useful = pat_ids.iter().any(|&pat_id| {
635 let v = PatStack::from_pattern(pat_id);
636
637 match is_useful(cx, matrix, &v) {
638 Ok(Usefulness::Useful) => true,
639 Ok(Usefulness::NotUseful) => false,
640 _ => {
641 found_unimplemented = true;
642 false
643 }
644 }
645 });
646
647 return if any_useful {
648 Ok(Usefulness::Useful)
649 } else if found_unimplemented {
650 Err(MatchCheckErr::NotImplemented)
651 } else {
652 Ok(Usefulness::NotUseful)
653 };
654 }
655
656 if let Some(constructor) = pat_constructor(cx, head)? {
657 let matrix = matrix.specialize_constructor(&cx, &constructor)?;
658 let v = v
659 .specialize_constructor(&cx, &constructor)?
660 .expect("we know this can't fail because we get the constructor from `v.head()` above");
661
662 is_useful(&cx, &matrix, &v)
663 } else {
664 // expanding wildcard
665 let mut used_constructors: Vec<Constructor> = vec![];
666 for pat in matrix.heads() {
667 if let Some(constructor) = pat_constructor(cx, pat)? {
668 used_constructors.push(constructor);
669 }
670 }
671
672 // We assume here that the first constructor is the "correct" type. Since we
673 // only care about the "type" of the constructor (i.e. if it is a bool we
674 // don't care about the value), this assumption should be valid as long as
675 // the match statement is well formed. We currently uphold this invariant by
676 // filtering match arms before calling `is_useful`, only passing in match arms
677 // whose type matches the type of the match expression.
678 match &used_constructors.first() {
679 Some(constructor) if all_constructors_covered(&cx, constructor, &used_constructors) => {
680 // If all constructors are covered, then we need to consider whether
681 // any values are covered by this wildcard.
682 //
683 // For example, with matrix '[[Some(true)], [None]]', all
684 // constructors are covered (`Some`/`None`), so we need
685 // to perform specialization to see that our wildcard will cover
686 // the `Some(false)` case.
687 //
688 // Here we create a constructor for each variant and then check
689 // usefulness after specializing for that constructor.
690 let mut found_unimplemented = false;
691 for constructor in constructor.all_constructors(cx) {
692 let matrix = matrix.specialize_constructor(&cx, &constructor)?;
693 let v = v.expand_wildcard(&cx, &constructor)?;
694
695 match is_useful(&cx, &matrix, &v) {
696 Ok(Usefulness::Useful) => return Ok(Usefulness::Useful),
697 Ok(Usefulness::NotUseful) => continue,
698 _ => found_unimplemented = true,
699 };
700 }
701
702 if found_unimplemented {
703 Err(MatchCheckErr::NotImplemented)
704 } else {
705 Ok(Usefulness::NotUseful)
706 }
707 }
708 _ => {
709 // Either not all constructors are covered, or the only other arms
710 // are wildcards. Either way, this pattern is useful if it is useful
711 // when compared to those arms with wildcards.
712 let matrix = matrix.specialize_wildcard(&cx);
713 let v = v.to_tail();
714
715 is_useful(&cx, &matrix, &v)
716 }
717 }
718 }
719}
720
721#[derive(Debug, Clone, Copy)]
722/// Similar to TypeCtor, but includes additional information about the specific
723/// value being instantiated. For example, TypeCtor::Bool doesn't contain the
724/// boolean value.
725enum Constructor {
726 Bool(bool),
727 Tuple { arity: usize },
728 Enum(EnumVariantId),
729}
730
731impl Constructor {
732 fn arity(&self, cx: &MatchCheckCtx) -> MatchCheckResult<usize> {
733 let arity = match self {
734 Constructor::Bool(_) => 0,
735 Constructor::Tuple { arity } => *arity,
736 Constructor::Enum(e) => {
737 match cx.db.enum_data(e.parent).variants[e.local_id].variant_data.as_ref() {
738 VariantData::Tuple(struct_field_data) => struct_field_data.len(),
739 VariantData::Record(struct_field_data) => struct_field_data.len(),
740 VariantData::Unit => 0,
741 }
742 }
743 };
744
745 Ok(arity)
746 }
747
748 fn all_constructors(&self, cx: &MatchCheckCtx) -> Vec<Constructor> {
749 match self {
750 Constructor::Bool(_) => vec![Constructor::Bool(true), Constructor::Bool(false)],
751 Constructor::Tuple { .. } => vec![*self],
752 Constructor::Enum(e) => cx
753 .db
754 .enum_data(e.parent)
755 .variants
756 .iter()
757 .map(|(local_id, _)| {
758 Constructor::Enum(EnumVariantId { parent: e.parent, local_id })
759 })
760 .collect(),
761 }
762 }
763}
764
765/// Returns the constructor for the given pattern. Should only return None
766/// in the case of a Wild pattern.
767fn pat_constructor(cx: &MatchCheckCtx, pat: PatIdOrWild) -> MatchCheckResult<Option<Constructor>> {
768 let res = match pat.as_pat(cx) {
769 Pat::Wild => None,
770 // FIXME somehow create the Tuple constructor with the proper arity. If there are
771 // ellipsis, the arity is not equal to the number of patterns.
772 Pat::Tuple { args: pats, ellipsis } if ellipsis.is_none() => {
773 Some(Constructor::Tuple { arity: pats.len() })
774 }
775 Pat::Lit(lit_expr) => match cx.body.exprs[lit_expr] {
776 Expr::Literal(Literal::Bool(val)) => Some(Constructor::Bool(val)),
777 _ => return Err(MatchCheckErr::NotImplemented),
778 },
779 Pat::TupleStruct { .. } | Pat::Path(_) | Pat::Record { .. } => {
780 let pat_id = pat.as_id().expect("we already know this pattern is not a wild");
781 let variant_id =
782 cx.infer.variant_resolution_for_pat(pat_id).ok_or(MatchCheckErr::Unknown)?;
783 match variant_id {
784 VariantId::EnumVariantId(enum_variant_id) => {
785 Some(Constructor::Enum(enum_variant_id))
786 }
787 _ => return Err(MatchCheckErr::NotImplemented),
788 }
789 }
790 _ => return Err(MatchCheckErr::NotImplemented),
791 };
792
793 Ok(res)
794}
795
796fn all_constructors_covered(
797 cx: &MatchCheckCtx,
798 constructor: &Constructor,
799 used_constructors: &[Constructor],
800) -> bool {
801 match constructor {
802 Constructor::Tuple { arity } => {
803 used_constructors.iter().any(|constructor| match constructor {
804 Constructor::Tuple { arity: used_arity } => arity == used_arity,
805 _ => false,
806 })
807 }
808 Constructor::Bool(_) => {
809 if used_constructors.is_empty() {
810 return false;
811 }
812
813 let covers_true =
814 used_constructors.iter().any(|c| matches!(c, Constructor::Bool(true)));
815 let covers_false =
816 used_constructors.iter().any(|c| matches!(c, Constructor::Bool(false)));
817
818 covers_true && covers_false
819 }
820 Constructor::Enum(e) => cx.db.enum_data(e.parent).variants.iter().all(|(id, _)| {
821 for constructor in used_constructors {
822 if let Constructor::Enum(e) = constructor {
823 if id == e.local_id {
824 return true;
825 }
826 }
827 }
828
829 false
830 }),
831 }
832}
833
834fn enum_variant_matches(cx: &MatchCheckCtx, pat_id: PatId, enum_variant_id: EnumVariantId) -> bool {
835 Some(enum_variant_id.into()) == cx.infer.variant_resolution_for_pat(pat_id)
836}
837
838#[cfg(test)]
839mod tests {
840 use crate::diagnostics::tests::check_diagnostics;
841
842 #[test]
843 fn empty_tuple() {
844 check_diagnostics(
845 r#"
846fn main() {
847 match () { }
848 //^^ Missing match arm
849 match (()) { }
850 //^^^^ Missing match arm
851
852 match () { _ => (), }
853 match () { () => (), }
854 match (()) { (()) => (), }
855}
856"#,
857 );
858 }
859
860 #[test]
861 fn tuple_of_two_empty_tuple() {
862 check_diagnostics(
863 r#"
864fn main() {
865 match ((), ()) { }
866 //^^^^^^^^ Missing match arm
867
868 match ((), ()) { ((), ()) => (), }
869}
870"#,
871 );
872 }
873
874 #[test]
875 fn boolean() {
876 check_diagnostics(
877 r#"
878fn test_main() {
879 match false { }
880 //^^^^^ Missing match arm
881 match false { true => (), }
882 //^^^^^ Missing match arm
883 match (false, true) {}
884 //^^^^^^^^^^^^^ Missing match arm
885 match (false, true) { (true, true) => (), }
886 //^^^^^^^^^^^^^ Missing match arm
887 match (false, true) {
888 //^^^^^^^^^^^^^ Missing match arm
889 (false, true) => (),
890 (false, false) => (),
891 (true, false) => (),
892 }
893 match (false, true) { (true, _x) => (), }
894 //^^^^^^^^^^^^^ Missing match arm
895
896 match false { true => (), false => (), }
897 match (false, true) {
898 (false, _) => (),
899 (true, false) => (),
900 (_, true) => (),
901 }
902 match (false, true) {
903 (true, true) => (),
904 (true, false) => (),
905 (false, true) => (),
906 (false, false) => (),
907 }
908 match (false, true) {
909 (true, _x) => (),
910 (false, true) => (),
911 (false, false) => (),
912 }
913 match (false, true, false) {
914 (false, ..) => (),
915 (true, ..) => (),
916 }
917 match (false, true, false) {
918 (.., false) => (),
919 (.., true) => (),
920 }
921 match (false, true, false) { (..) => (), }
922}
923"#,
924 );
925 }
926
927 #[test]
928 fn tuple_of_tuple_and_bools() {
929 check_diagnostics(
930 r#"
931fn main() {
932 match (false, ((), false)) {}
933 //^^^^^^^^^^^^^^^^^^^^ Missing match arm
934 match (false, ((), false)) { (true, ((), true)) => (), }
935 //^^^^^^^^^^^^^^^^^^^^ Missing match arm
936 match (false, ((), false)) { (true, _) => (), }
937 //^^^^^^^^^^^^^^^^^^^^ Missing match arm
938
939 match (false, ((), false)) {
940 (true, ((), true)) => (),
941 (true, ((), false)) => (),
942 (false, ((), true)) => (),
943 (false, ((), false)) => (),
944 }
945 match (false, ((), false)) {
946 (true, ((), true)) => (),
947 (true, ((), false)) => (),
948 (false, _) => (),
949 }
950}
951"#,
952 );
953 }
954
955 #[test]
956 fn enums() {
957 check_diagnostics(
958 r#"
959enum Either { A, B, }
960
961fn main() {
962 match Either::A { }
963 //^^^^^^^^^ Missing match arm
964 match Either::B { Either::A => (), }
965 //^^^^^^^^^ Missing match arm
966
967 match &Either::B {
968 //^^^^^^^^^^ Missing match arm
969 Either::A => (),
970 }
971
972 match Either::B {
973 Either::A => (), Either::B => (),
974 }
975 match &Either::B {
976 Either::A => (), Either::B => (),
977 }
978}
979"#,
980 );
981 }
982
983 #[test]
984 fn enum_containing_bool() {
985 check_diagnostics(
986 r#"
987enum Either { A(bool), B }
988
989fn main() {
990 match Either::B { }
991 //^^^^^^^^^ Missing match arm
992 match Either::B {
993 //^^^^^^^^^ Missing match arm
994 Either::A(true) => (), Either::B => ()
995 }
996
997 match Either::B {
998 Either::A(true) => (),
999 Either::A(false) => (),
1000 Either::B => (),
1001 }
1002 match Either::B {
1003 Either::B => (),
1004 _ => (),
1005 }
1006 match Either::B {
1007 Either::A(_) => (),
1008 Either::B => (),
1009 }
1010
1011}
1012 "#,
1013 );
1014 }
1015
1016 #[test]
1017 fn enum_different_sizes() {
1018 check_diagnostics(
1019 r#"
1020enum Either { A(bool), B(bool, bool) }
1021
1022fn main() {
1023 match Either::A(false) {
1024 //^^^^^^^^^^^^^^^^ Missing match arm
1025 Either::A(_) => (),
1026 Either::B(false, _) => (),
1027 }
1028
1029 match Either::A(false) {
1030 Either::A(_) => (),
1031 Either::B(true, _) => (),
1032 Either::B(false, _) => (),
1033 }
1034 match Either::A(false) {
1035 Either::A(true) | Either::A(false) => (),
1036 Either::B(true, _) => (),
1037 Either::B(false, _) => (),
1038 }
1039}
1040"#,
1041 );
1042 }
1043
1044 #[test]
1045 fn tuple_of_enum_no_diagnostic() {
1046 check_diagnostics(
1047 r#"
1048enum Either { A(bool), B(bool, bool) }
1049enum Either2 { C, D }
1050
1051fn main() {
1052 match (Either::A(false), Either2::C) {
1053 (Either::A(true), _) | (Either::A(false), _) => (),
1054 (Either::B(true, _), Either2::C) => (),
1055 (Either::B(false, _), Either2::C) => (),
1056 (Either::B(_, _), Either2::D) => (),
1057 }
1058}
1059"#,
1060 );
1061 }
1062
1063 #[test]
1064 fn mismatched_types() {
1065 // Match statements with arms that don't match the
1066 // expression pattern do not fire this diagnostic.
1067 check_diagnostics(
1068 r#"
1069enum Either { A, B }
1070enum Either2 { C, D }
1071
1072fn main() {
1073 match Either::A {
1074 Either2::C => (),
1075 Either2::D => (),
1076 }
1077 match (true, false) {
1078 (true, false, true) => (),
1079 (true) => (),
1080 }
1081 match (0) { () => () }
1082 match Unresolved::Bar { Unresolved::Baz => () }
1083}
1084 "#,
1085 );
1086 }
1087
1088 #[test]
1089 fn malformed_match_arm_tuple_enum_missing_pattern() {
1090 // We are testing to be sure we don't panic here when the match
1091 // arm `Either::B` is missing its pattern.
1092 check_diagnostics(
1093 r#"
1094enum Either { A, B(u32) }
1095
1096fn main() {
1097 match Either::A {
1098 Either::A => (),
1099 Either::B() => (),
1100 }
1101}
1102"#,
1103 );
1104 }
1105
1106 #[test]
1107 fn expr_diverges() {
1108 check_diagnostics(
1109 r#"
1110enum Either { A, B }
1111
1112fn main() {
1113 match loop {} {
1114 Either::A => (),
1115 Either::B => (),
1116 }
1117 match loop {} {
1118 Either::A => (),
1119 }
1120 match loop { break Foo::A } {
1121 //^^^^^^^^^^^^^^^^^^^^^ Missing match arm
1122 Either::A => (),
1123 }
1124 match loop { break Foo::A } {
1125 Either::A => (),
1126 Either::B => (),
1127 }
1128}
1129"#,
1130 );
1131 }
1132
1133 #[test]
1134 fn expr_partially_diverges() {
1135 check_diagnostics(
1136 r#"
1137enum Either<T> { A(T), B }
1138
1139fn foo() -> Either<!> { Either::B }
1140fn main() -> u32 {
1141 match foo() {
1142 Either::A(val) => val,
1143 Either::B => 0,
1144 }
1145}
1146"#,
1147 );
1148 }
1149
1150 #[test]
1151 fn enum_record() {
1152 check_diagnostics(
1153 r#"
1154enum Either { A { foo: bool }, B }
1155
1156fn main() {
1157 let a = Either::A { foo: true };
1158 match a { }
1159 //^ Missing match arm
1160 match a { Either::A { foo: true } => () }
1161 //^ Missing match arm
1162 match a {
1163 Either::A { } => (),
1164 //^^^^^^^^^ Missing structure fields:
1165 // | - foo
1166 Either::B => (),
1167 }
1168 match a {
1169 //^ Missing match arm
1170 Either::A { } => (),
1171 } //^^^^^^^^^ Missing structure fields:
1172 // | - foo
1173
1174 match a {
1175 Either::A { foo: true } => (),
1176 Either::A { foo: false } => (),
1177 Either::B => (),
1178 }
1179 match a {
1180 Either::A { foo: _ } => (),
1181 Either::B => (),
1182 }
1183}
1184"#,
1185 );
1186 }
1187
1188 #[test]
1189 fn enum_record_fields_out_of_order() {
1190 check_diagnostics(
1191 r#"
1192enum Either {
1193 A { foo: bool, bar: () },
1194 B,
1195}
1196
1197fn main() {
1198 let a = Either::A { foo: true, bar: () };
1199 match a {
1200 //^ Missing match arm
1201 Either::A { bar: (), foo: false } => (),
1202 Either::A { foo: true, bar: () } => (),
1203 }
1204
1205 match a {
1206 Either::A { bar: (), foo: false } => (),
1207 Either::A { foo: true, bar: () } => (),
1208 Either::B => (),
1209 }
1210}
1211"#,
1212 );
1213 }
1214
1215 #[test]
1216 fn enum_record_ellipsis() {
1217 check_diagnostics(
1218 r#"
1219enum Either {
1220 A { foo: bool, bar: bool },
1221 B,
1222}
1223
1224fn main() {
1225 let a = Either::B;
1226 match a {
1227 //^ Missing match arm
1228 Either::A { foo: true, .. } => (),
1229 Either::B => (),
1230 }
1231 match a {
1232 //^ Missing match arm
1233 Either::A { .. } => (),
1234 }
1235
1236 match a {
1237 Either::A { foo: true, .. } => (),
1238 Either::A { foo: false, .. } => (),
1239 Either::B => (),
1240 }
1241
1242 match a {
1243 Either::A { .. } => (),
1244 Either::B => (),
1245 }
1246}
1247"#,
1248 );
1249 }
1250
1251 #[test]
1252 fn enum_tuple_partial_ellipsis() {
1253 check_diagnostics(
1254 r#"
1255enum Either {
1256 A(bool, bool, bool, bool),
1257 B,
1258}
1259
1260fn main() {
1261 match Either::B {
1262 //^^^^^^^^^ Missing match arm
1263 Either::A(true, .., true) => (),
1264 Either::A(true, .., false) => (),
1265 Either::A(false, .., false) => (),
1266 Either::B => (),
1267 }
1268 match Either::B {
1269 //^^^^^^^^^ Missing match arm
1270 Either::A(true, .., true) => (),
1271 Either::A(true, .., false) => (),
1272 Either::A(.., true) => (),
1273 Either::B => (),
1274 }
1275
1276 match Either::B {
1277 Either::A(true, .., true) => (),
1278 Either::A(true, .., false) => (),
1279 Either::A(false, .., true) => (),
1280 Either::A(false, .., false) => (),
1281 Either::B => (),
1282 }
1283 match Either::B {
1284 Either::A(true, .., true) => (),
1285 Either::A(true, .., false) => (),
1286 Either::A(.., true) => (),
1287 Either::A(.., false) => (),
1288 Either::B => (),
1289 }
1290}
1291"#,
1292 );
1293 }
1294
1295 #[test]
1296 fn never() {
1297 check_diagnostics(
1298 r#"
1299enum Never {}
1300
1301fn enum_(never: Never) {
1302 match never {}
1303}
1304fn enum_ref(never: &Never) {
1305 match never {}
1306}
1307fn bang(never: !) {
1308 match never {}
1309}
1310"#,
1311 );
1312 }
1313
1314 #[test]
1315 fn or_pattern_panic() {
1316 check_diagnostics(
1317 r#"
1318pub enum Category { Infinity, Zero }
1319
1320fn panic(a: Category, b: Category) {
1321 match (a, b) {
1322 (Category::Zero | Category::Infinity, _) => (),
1323 (_, Category::Zero | Category::Infinity) => (),
1324 }
1325
1326 // FIXME: This is a false positive, but the code used to cause a panic in the match checker,
1327 // so this acts as a regression test for that.
1328 match (a, b) {
1329 //^^^^^^ Missing match arm
1330 (Category::Infinity, Category::Infinity) | (Category::Zero, Category::Zero) => (),
1331 (Category::Infinity | Category::Zero, _) => (),
1332 }
1333}
1334"#,
1335 );
1336 }
1337
1338 mod false_negatives {
1339 //! The implementation of match checking here is a work in progress. As we roll this out, we
1340 //! prefer false negatives to false positives (ideally there would be no false positives). This
1341 //! test module should document known false negatives. Eventually we will have a complete
1342 //! implementation of match checking and this module will be empty.
1343 //!
1344 //! The reasons for documenting known false negatives:
1345 //!
1346 //! 1. It acts as a backlog of work that can be done to improve the behavior of the system.
1347 //! 2. It ensures the code doesn't panic when handling these cases.
1348 use super::*;
1349
1350 #[test]
1351 fn integers() {
1352 // We don't currently check integer exhaustiveness.
1353 check_diagnostics(
1354 r#"
1355fn main() {
1356 match 5 {
1357 10 => (),
1358 11..20 => (),
1359 }
1360}
1361"#,
1362 );
1363 }
1364
1365 #[test]
1366 fn internal_or() {
1367 // We do not currently handle patterns with internal `or`s.
1368 check_diagnostics(
1369 r#"
1370fn main() {
1371 enum Either { A(bool), B }
1372 match Either::B {
1373 Either::A(true | false) => (),
1374 }
1375}
1376"#,
1377 );
1378 }
1379
1380 #[test]
1381 fn tuple_of_bools_with_ellipsis_at_end_missing_arm() {
1382 // We don't currently handle tuple patterns with ellipsis.
1383 check_diagnostics(
1384 r#"
1385fn main() {
1386 match (false, true, false) {
1387 (false, ..) => (),
1388 }
1389}
1390"#,
1391 );
1392 }
1393
1394 #[test]
1395 fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() {
1396 // We don't currently handle tuple patterns with ellipsis.
1397 check_diagnostics(
1398 r#"
1399fn main() {
1400 match (false, true, false) {
1401 (.., false) => (),
1402 }
1403}
1404"#,
1405 );
1406 }
1407
1408 #[test]
1409 fn struct_missing_arm() {
1410 // We don't currently handle structs.
1411 check_diagnostics(
1412 r#"
1413struct Foo { a: bool }
1414fn main(f: Foo) {
1415 match f { Foo { a: true } => () }
1416}
1417"#,
1418 );
1419 }
1420 }
1421}
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
new file mode 100644
index 000000000..61ffbf5d1
--- /dev/null
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -0,0 +1,205 @@
1//! Provides validations for unsafe code. Currently checks if unsafe functions are missing
2//! unsafe blocks.
3
4use std::sync::Arc;
5
6use hir_def::{
7 body::Body,
8 expr::{Expr, ExprId, UnaryOp},
9 resolver::{resolver_for_expr, ResolveValueResult, ValueNs},
10 DefWithBodyId,
11};
12use hir_expand::diagnostics::DiagnosticSink;
13
14use crate::{
15 db::HirDatabase, diagnostics::MissingUnsafe, lower::CallableDefId, ApplicationTy,
16 InferenceResult, Ty, TypeCtor,
17};
18
19pub(super) struct UnsafeValidator<'a, 'b: 'a> {
20 owner: DefWithBodyId,
21 infer: Arc<InferenceResult>,
22 sink: &'a mut DiagnosticSink<'b>,
23}
24
25impl<'a, 'b> UnsafeValidator<'a, 'b> {
26 pub(super) fn new(
27 owner: DefWithBodyId,
28 infer: Arc<InferenceResult>,
29 sink: &'a mut DiagnosticSink<'b>,
30 ) -> UnsafeValidator<'a, 'b> {
31 UnsafeValidator { owner, infer, sink }
32 }
33
34 pub(super) fn validate_body(&mut self, db: &dyn HirDatabase) {
35 let def = self.owner.into();
36 let unsafe_expressions = unsafe_expressions(db, self.infer.as_ref(), def);
37 let is_unsafe = match self.owner {
38 DefWithBodyId::FunctionId(it) => db.function_data(it).is_unsafe,
39 DefWithBodyId::StaticId(_) | DefWithBodyId::ConstId(_) => false,
40 };
41 if is_unsafe
42 || unsafe_expressions
43 .iter()
44 .filter(|unsafe_expr| !unsafe_expr.inside_unsafe_block)
45 .count()
46 == 0
47 {
48 return;
49 }
50
51 let (_, body_source) = db.body_with_source_map(def);
52 for unsafe_expr in unsafe_expressions {
53 if !unsafe_expr.inside_unsafe_block {
54 if let Ok(in_file) = body_source.as_ref().expr_syntax(unsafe_expr.expr) {
55 self.sink.push(MissingUnsafe { file: in_file.file_id, expr: in_file.value })
56 }
57 }
58 }
59 }
60}
61
62pub struct UnsafeExpr {
63 pub expr: ExprId,
64 pub inside_unsafe_block: bool,
65}
66
67pub fn unsafe_expressions(
68 db: &dyn HirDatabase,
69 infer: &InferenceResult,
70 def: DefWithBodyId,
71) -> Vec<UnsafeExpr> {
72 let mut unsafe_exprs = vec![];
73 let body = db.body(def);
74 walk_unsafe(&mut unsafe_exprs, db, infer, def, &body, body.body_expr, false);
75
76 unsafe_exprs
77}
78
79fn walk_unsafe(
80 unsafe_exprs: &mut Vec<UnsafeExpr>,
81 db: &dyn HirDatabase,
82 infer: &InferenceResult,
83 def: DefWithBodyId,
84 body: &Body,
85 current: ExprId,
86 inside_unsafe_block: bool,
87) {
88 let expr = &body.exprs[current];
89 match expr {
90 Expr::Call { callee, .. } => {
91 let ty = &infer[*callee];
92 if let &Ty::Apply(ApplicationTy {
93 ctor: TypeCtor::FnDef(CallableDefId::FunctionId(func)),
94 ..
95 }) = ty
96 {
97 if db.function_data(func).is_unsafe {
98 unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
99 }
100 }
101 }
102 Expr::Path(path) => {
103 let resolver = resolver_for_expr(db.upcast(), def, current);
104 let value_or_partial = resolver.resolve_path_in_value_ns(db.upcast(), path.mod_path());
105 if let Some(ResolveValueResult::ValueNs(ValueNs::StaticId(id))) = value_or_partial {
106 if db.static_data(id).mutable {
107 unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
108 }
109 }
110 }
111 Expr::MethodCall { .. } => {
112 if infer
113 .method_resolution(current)
114 .map(|func| db.function_data(func).is_unsafe)
115 .unwrap_or(false)
116 {
117 unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
118 }
119 }
120 Expr::UnaryOp { expr, op: UnaryOp::Deref } => {
121 if let Ty::Apply(ApplicationTy { ctor: TypeCtor::RawPtr(..), .. }) = &infer[*expr] {
122 unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
123 }
124 }
125 Expr::Unsafe { body: child } => {
126 return walk_unsafe(unsafe_exprs, db, infer, def, body, *child, true);
127 }
128 _ => {}
129 }
130
131 expr.walk_child_exprs(|child| {
132 walk_unsafe(unsafe_exprs, db, infer, def, body, child, inside_unsafe_block);
133 });
134}
135
136#[cfg(test)]
137mod tests {
138 use crate::diagnostics::tests::check_diagnostics;
139
140 #[test]
141 fn missing_unsafe_diagnostic_with_raw_ptr() {
142 check_diagnostics(
143 r#"
144fn main() {
145 let x = &5 as *const usize;
146 unsafe { let y = *x; }
147 let z = *x;
148} //^^ This operation is unsafe and requires an unsafe function or block
149"#,
150 )
151 }
152
153 #[test]
154 fn missing_unsafe_diagnostic_with_unsafe_call() {
155 check_diagnostics(
156 r#"
157struct HasUnsafe;
158
159impl HasUnsafe {
160 unsafe fn unsafe_fn(&self) {
161 let x = &5 as *const usize;
162 let y = *x;
163 }
164}
165
166unsafe fn unsafe_fn() {
167 let x = &5 as *const usize;
168 let y = *x;
169}
170
171fn main() {
172 unsafe_fn();
173 //^^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
174 HasUnsafe.unsafe_fn();
175 //^^^^^^^^^^^^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
176 unsafe {
177 unsafe_fn();
178 HasUnsafe.unsafe_fn();
179 }
180}
181"#,
182 );
183 }
184
185 #[test]
186 fn missing_unsafe_diagnostic_with_static_mut() {
187 check_diagnostics(
188 r#"
189struct Ty {
190 a: u8,
191}
192
193static mut static_mut: Ty = Ty { a: 0 };
194
195fn main() {
196 let x = static_mut.a;
197 //^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
198 unsafe {
199 let x = static_mut.a;
200 }
201}
202"#,
203 );
204 }
205}
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
new file mode 100644
index 000000000..64b68014d
--- /dev/null
+++ b/crates/hir_ty/src/display.rs
@@ -0,0 +1,632 @@
1//! FIXME: write short doc here
2
3use std::fmt;
4
5use crate::{
6 db::HirDatabase, utils::generics, ApplicationTy, CallableDefId, FnSig, GenericPredicate,
7 Obligation, OpaqueTyId, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
8};
9use hir_def::{
10 find_path, generics::TypeParamProvenance, item_scope::ItemInNs, AdtId, AssocContainerId,
11 Lookup, ModuleId,
12};
13use hir_expand::name::Name;
14
15pub struct HirFormatter<'a> {
16 pub db: &'a dyn HirDatabase,
17 fmt: &'a mut dyn fmt::Write,
18 buf: String,
19 curr_size: usize,
20 pub(crate) max_size: Option<usize>,
21 omit_verbose_types: bool,
22 display_target: DisplayTarget,
23}
24
25pub trait HirDisplay {
26 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError>;
27
28 /// Returns a `Display`able type that is human-readable.
29 /// Use this for showing types to the user (e.g. diagnostics)
30 fn display<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
31 where
32 Self: Sized,
33 {
34 HirDisplayWrapper {
35 db,
36 t: self,
37 max_size: None,
38 omit_verbose_types: false,
39 display_target: DisplayTarget::Diagnostics,
40 }
41 }
42
43 /// Returns a `Display`able type that is human-readable and tries to be succinct.
44 /// Use this for showing types to the user where space is constrained (e.g. doc popups)
45 fn display_truncated<'a>(
46 &'a self,
47 db: &'a dyn HirDatabase,
48 max_size: Option<usize>,
49 ) -> HirDisplayWrapper<'a, Self>
50 where
51 Self: Sized,
52 {
53 HirDisplayWrapper {
54 db,
55 t: self,
56 max_size,
57 omit_verbose_types: true,
58 display_target: DisplayTarget::Diagnostics,
59 }
60 }
61
62 /// Returns a String representation of `self` that can be inserted into the given module.
63 /// Use this when generating code (e.g. assists)
64 fn display_source_code<'a>(
65 &'a self,
66 db: &'a dyn HirDatabase,
67 module_id: ModuleId,
68 ) -> Result<String, DisplaySourceCodeError> {
69 let mut result = String::new();
70 match self.hir_fmt(&mut HirFormatter {
71 db,
72 fmt: &mut result,
73 buf: String::with_capacity(20),
74 curr_size: 0,
75 max_size: None,
76 omit_verbose_types: false,
77 display_target: DisplayTarget::SourceCode { module_id },
78 }) {
79 Ok(()) => {}
80 Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
81 Err(HirDisplayError::DisplaySourceCodeError(e)) => return Err(e),
82 };
83 Ok(result)
84 }
85}
86
87impl<'a> HirFormatter<'a> {
88 pub fn write_joined<T: HirDisplay>(
89 &mut self,
90 iter: impl IntoIterator<Item = T>,
91 sep: &str,
92 ) -> Result<(), HirDisplayError> {
93 let mut first = true;
94 for e in iter {
95 if !first {
96 write!(self, "{}", sep)?;
97 }
98 first = false;
99 e.hir_fmt(self)?;
100 }
101 Ok(())
102 }
103
104 /// This allows using the `write!` macro directly with a `HirFormatter`.
105 pub fn write_fmt(&mut self, args: fmt::Arguments) -> Result<(), HirDisplayError> {
106 // We write to a buffer first to track output size
107 self.buf.clear();
108 fmt::write(&mut self.buf, args)?;
109 self.curr_size += self.buf.len();
110
111 // Then we write to the internal formatter from the buffer
112 self.fmt.write_str(&self.buf).map_err(HirDisplayError::from)
113 }
114
115 pub fn should_truncate(&self) -> bool {
116 if let Some(max_size) = self.max_size {
117 self.curr_size >= max_size
118 } else {
119 false
120 }
121 }
122
123 pub fn omit_verbose_types(&self) -> bool {
124 self.omit_verbose_types
125 }
126}
127
128#[derive(Clone, Copy)]
129enum DisplayTarget {
130 /// Display types for inlays, doc popups, autocompletion, etc...
131 /// Showing `{unknown}` or not qualifying paths is fine here.
132 /// There's no reason for this to fail.
133 Diagnostics,
134 /// Display types for inserting them in source files.
135 /// The generated code should compile, so paths need to be qualified.
136 SourceCode { module_id: ModuleId },
137}
138
139impl DisplayTarget {
140 fn is_source_code(&self) -> bool {
141 matches!(self, Self::SourceCode {..})
142 }
143}
144
145#[derive(Debug)]
146pub enum DisplaySourceCodeError {
147 PathNotFound,
148}
149
150pub enum HirDisplayError {
151 /// Errors that can occur when generating source code
152 DisplaySourceCodeError(DisplaySourceCodeError),
153 /// `FmtError` is required to be compatible with std::fmt::Display
154 FmtError,
155}
156impl From<fmt::Error> for HirDisplayError {
157 fn from(_: fmt::Error) -> Self {
158 Self::FmtError
159 }
160}
161
162pub struct HirDisplayWrapper<'a, T> {
163 db: &'a dyn HirDatabase,
164 t: &'a T,
165 max_size: Option<usize>,
166 omit_verbose_types: bool,
167 display_target: DisplayTarget,
168}
169
170impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
171where
172 T: HirDisplay,
173{
174 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
175 match self.t.hir_fmt(&mut HirFormatter {
176 db: self.db,
177 fmt: f,
178 buf: String::with_capacity(20),
179 curr_size: 0,
180 max_size: self.max_size,
181 omit_verbose_types: self.omit_verbose_types,
182 display_target: self.display_target,
183 }) {
184 Ok(()) => Ok(()),
185 Err(HirDisplayError::FmtError) => Err(fmt::Error),
186 Err(HirDisplayError::DisplaySourceCodeError(_)) => {
187 // This should never happen
188 panic!("HirDisplay failed when calling Display::fmt!")
189 }
190 }
191 }
192}
193
194const TYPE_HINT_TRUNCATION: &str = "…";
195
196impl HirDisplay for &Ty {
197 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
198 HirDisplay::hir_fmt(*self, f)
199 }
200}
201
202impl HirDisplay for ApplicationTy {
203 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
204 if f.should_truncate() {
205 return write!(f, "{}", TYPE_HINT_TRUNCATION);
206 }
207
208 match self.ctor {
209 TypeCtor::Bool => write!(f, "bool")?,
210 TypeCtor::Char => write!(f, "char")?,
211 TypeCtor::Int(t) => write!(f, "{}", t)?,
212 TypeCtor::Float(t) => write!(f, "{}", t)?,
213 TypeCtor::Str => write!(f, "str")?,
214 TypeCtor::Slice => {
215 let t = self.parameters.as_single();
216 write!(f, "[{}]", t.display(f.db))?;
217 }
218 TypeCtor::Array => {
219 let t = self.parameters.as_single();
220 write!(f, "[{}; _]", t.display(f.db))?;
221 }
222 TypeCtor::RawPtr(m) => {
223 let t = self.parameters.as_single();
224 write!(f, "*{}{}", m.as_keyword_for_ptr(), t.display(f.db))?;
225 }
226 TypeCtor::Ref(m) => {
227 let t = self.parameters.as_single();
228 let ty_display = if f.omit_verbose_types() {
229 t.display_truncated(f.db, f.max_size)
230 } else {
231 t.display(f.db)
232 };
233 write!(f, "&{}{}", m.as_keyword_for_ref(), ty_display)?;
234 }
235 TypeCtor::Never => write!(f, "!")?,
236 TypeCtor::Tuple { .. } => {
237 let ts = &self.parameters;
238 if ts.len() == 1 {
239 write!(f, "({},)", ts[0].display(f.db))?;
240 } else {
241 write!(f, "(")?;
242 f.write_joined(&*ts.0, ", ")?;
243 write!(f, ")")?;
244 }
245 }
246 TypeCtor::FnPtr { is_varargs, .. } => {
247 let sig = FnSig::from_fn_ptr_substs(&self.parameters, is_varargs);
248 write!(f, "fn(")?;
249 f.write_joined(sig.params(), ", ")?;
250 if is_varargs {
251 if sig.params().is_empty() {
252 write!(f, "...")?;
253 } else {
254 write!(f, ", ...")?;
255 }
256 }
257 write!(f, ")")?;
258 let ret = sig.ret();
259 if *ret != Ty::unit() {
260 let ret_display = if f.omit_verbose_types() {
261 ret.display_truncated(f.db, f.max_size)
262 } else {
263 ret.display(f.db)
264 };
265 write!(f, " -> {}", ret_display)?;
266 }
267 }
268 TypeCtor::FnDef(def) => {
269 let sig = f.db.callable_item_signature(def).subst(&self.parameters);
270 match def {
271 CallableDefId::FunctionId(ff) => {
272 write!(f, "fn {}", f.db.function_data(ff).name)?
273 }
274 CallableDefId::StructId(s) => write!(f, "{}", f.db.struct_data(s).name)?,
275 CallableDefId::EnumVariantId(e) => {
276 write!(f, "{}", f.db.enum_data(e.parent).variants[e.local_id].name)?
277 }
278 };
279 if self.parameters.len() > 0 {
280 let generics = generics(f.db.upcast(), def.into());
281 let (parent_params, self_param, type_params, _impl_trait_params) =
282 generics.provenance_split();
283 let total_len = parent_params + self_param + type_params;
284 // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
285 if total_len > 0 {
286 write!(f, "<")?;
287 f.write_joined(&self.parameters.0[..total_len], ", ")?;
288 write!(f, ">")?;
289 }
290 }
291 write!(f, "(")?;
292 f.write_joined(sig.params(), ", ")?;
293 write!(f, ")")?;
294 let ret = sig.ret();
295 if *ret != Ty::unit() {
296 let ret_display = if f.omit_verbose_types() {
297 ret.display_truncated(f.db, f.max_size)
298 } else {
299 ret.display(f.db)
300 };
301 write!(f, " -> {}", ret_display)?;
302 }
303 }
304 TypeCtor::Adt(def_id) => {
305 match f.display_target {
306 DisplayTarget::Diagnostics => {
307 let name = match def_id {
308 AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
309 AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
310 AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
311 };
312 write!(f, "{}", name)?;
313 }
314 DisplayTarget::SourceCode { module_id } => {
315 if let Some(path) = find_path::find_path(
316 f.db.upcast(),
317 ItemInNs::Types(def_id.into()),
318 module_id,
319 ) {
320 write!(f, "{}", path)?;
321 } else {
322 return Err(HirDisplayError::DisplaySourceCodeError(
323 DisplaySourceCodeError::PathNotFound,
324 ));
325 }
326 }
327 }
328
329 if self.parameters.len() > 0 {
330 let parameters_to_write =
331 if f.display_target.is_source_code() || f.omit_verbose_types() {
332 match self
333 .ctor
334 .as_generic_def()
335 .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
336 .filter(|defaults| !defaults.is_empty())
337 {
338 None => self.parameters.0.as_ref(),
339 Some(default_parameters) => {
340 let mut default_from = 0;
341 for (i, parameter) in self.parameters.iter().enumerate() {
342 match (parameter, default_parameters.get(i)) {
343 (&Ty::Unknown, _) | (_, None) => {
344 default_from = i + 1;
345 }
346 (_, Some(default_parameter)) => {
347 let actual_default = default_parameter
348 .clone()
349 .subst(&self.parameters.prefix(i));
350 if parameter != &actual_default {
351 default_from = i + 1;
352 }
353 }
354 }
355 }
356 &self.parameters.0[0..default_from]
357 }
358 }
359 } else {
360 self.parameters.0.as_ref()
361 };
362 if !parameters_to_write.is_empty() {
363 write!(f, "<")?;
364 f.write_joined(parameters_to_write, ", ")?;
365 write!(f, ">")?;
366 }
367 }
368 }
369 TypeCtor::AssociatedType(type_alias) => {
370 let trait_ = match type_alias.lookup(f.db.upcast()).container {
371 AssocContainerId::TraitId(it) => it,
372 _ => panic!("not an associated type"),
373 };
374 let trait_ = f.db.trait_data(trait_);
375 let type_alias = f.db.type_alias_data(type_alias);
376 write!(f, "{}::{}", trait_.name, type_alias.name)?;
377 if self.parameters.len() > 0 {
378 write!(f, "<")?;
379 f.write_joined(&*self.parameters.0, ", ")?;
380 write!(f, ">")?;
381 }
382 }
383 TypeCtor::OpaqueType(opaque_ty_id) => {
384 let bounds = match opaque_ty_id {
385 OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
386 let datas =
387 f.db.return_type_impl_traits(func).expect("impl trait id without data");
388 let data = (*datas)
389 .as_ref()
390 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
391 data.subst(&self.parameters)
392 }
393 };
394 write!(f, "impl ")?;
395 write_bounds_like_dyn_trait(&bounds.value, f)?;
396 // FIXME: it would maybe be good to distinguish this from the alias type (when debug printing), and to show the substitution
397 }
398 TypeCtor::Closure { .. } => {
399 let sig = self.parameters[0].callable_sig(f.db);
400 if let Some(sig) = sig {
401 if sig.params().is_empty() {
402 write!(f, "||")?;
403 } else if f.omit_verbose_types() {
404 write!(f, "|{}|", TYPE_HINT_TRUNCATION)?;
405 } else {
406 write!(f, "|")?;
407 f.write_joined(sig.params(), ", ")?;
408 write!(f, "|")?;
409 };
410
411 let ret_display = if f.omit_verbose_types() {
412 sig.ret().display_truncated(f.db, f.max_size)
413 } else {
414 sig.ret().display(f.db)
415 };
416 write!(f, " -> {}", ret_display)?;
417 } else {
418 write!(f, "{{closure}}")?;
419 }
420 }
421 }
422 Ok(())
423 }
424}
425
426impl HirDisplay for ProjectionTy {
427 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
428 if f.should_truncate() {
429 return write!(f, "{}", TYPE_HINT_TRUNCATION);
430 }
431
432 let trait_ = f.db.trait_data(self.trait_(f.db));
433 write!(f, "<{} as {}", self.parameters[0].display(f.db), trait_.name)?;
434 if self.parameters.len() > 1 {
435 write!(f, "<")?;
436 f.write_joined(&self.parameters[1..], ", ")?;
437 write!(f, ">")?;
438 }
439 write!(f, ">::{}", f.db.type_alias_data(self.associated_ty).name)?;
440 Ok(())
441 }
442}
443
444impl HirDisplay for Ty {
445 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
446 if f.should_truncate() {
447 return write!(f, "{}", TYPE_HINT_TRUNCATION);
448 }
449
450 match self {
451 Ty::Apply(a_ty) => a_ty.hir_fmt(f)?,
452 Ty::Projection(p_ty) => p_ty.hir_fmt(f)?,
453 Ty::Placeholder(id) => {
454 let generics = generics(f.db.upcast(), id.parent);
455 let param_data = &generics.params.types[id.local_id];
456 match param_data.provenance {
457 TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
458 write!(f, "{}", param_data.name.clone().unwrap_or_else(Name::missing))?
459 }
460 TypeParamProvenance::ArgumentImplTrait => {
461 write!(f, "impl ")?;
462 let bounds = f.db.generic_predicates_for_param(*id);
463 let substs = Substs::type_params_for_generics(&generics);
464 write_bounds_like_dyn_trait(
465 &bounds.iter().map(|b| b.clone().subst(&substs)).collect::<Vec<_>>(),
466 f,
467 )?;
468 }
469 }
470 }
471 Ty::Bound(idx) => write!(f, "?{}.{}", idx.debruijn.depth(), idx.index)?,
472 Ty::Dyn(predicates) => {
473 write!(f, "dyn ")?;
474 write_bounds_like_dyn_trait(predicates, f)?;
475 }
476 Ty::Opaque(opaque_ty) => {
477 let bounds = match opaque_ty.opaque_ty_id {
478 OpaqueTyId::ReturnTypeImplTrait(func, idx) => {
479 let datas =
480 f.db.return_type_impl_traits(func).expect("impl trait id without data");
481 let data = (*datas)
482 .as_ref()
483 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
484 data.subst(&opaque_ty.parameters)
485 }
486 };
487 write!(f, "impl ")?;
488 write_bounds_like_dyn_trait(&bounds.value, f)?;
489 }
490 Ty::Unknown => write!(f, "{{unknown}}")?,
491 Ty::Infer(..) => write!(f, "_")?,
492 }
493 Ok(())
494 }
495}
496
497fn write_bounds_like_dyn_trait(
498 predicates: &[GenericPredicate],
499 f: &mut HirFormatter,
500) -> Result<(), HirDisplayError> {
501 // Note: This code is written to produce nice results (i.e.
502 // corresponding to surface Rust) for types that can occur in
503 // actual Rust. It will have weird results if the predicates
504 // aren't as expected (i.e. self types = $0, projection
505 // predicates for a certain trait come after the Implemented
506 // predicate for that trait).
507 let mut first = true;
508 let mut angle_open = false;
509 for p in predicates.iter() {
510 match p {
511 GenericPredicate::Implemented(trait_ref) => {
512 if angle_open {
513 write!(f, ">")?;
514 angle_open = false;
515 }
516 if !first {
517 write!(f, " + ")?;
518 }
519 // We assume that the self type is $0 (i.e. the
520 // existential) here, which is the only thing that's
521 // possible in actual Rust, and hence don't print it
522 write!(f, "{}", f.db.trait_data(trait_ref.trait_).name)?;
523 if trait_ref.substs.len() > 1 {
524 write!(f, "<")?;
525 f.write_joined(&trait_ref.substs[1..], ", ")?;
526 // there might be assoc type bindings, so we leave the angle brackets open
527 angle_open = true;
528 }
529 }
530 GenericPredicate::Projection(projection_pred) => {
531 // in types in actual Rust, these will always come
532 // after the corresponding Implemented predicate
533 if angle_open {
534 write!(f, ", ")?;
535 } else {
536 write!(f, "<")?;
537 angle_open = true;
538 }
539 let type_alias = f.db.type_alias_data(projection_pred.projection_ty.associated_ty);
540 write!(f, "{} = ", type_alias.name)?;
541 projection_pred.ty.hir_fmt(f)?;
542 }
543 GenericPredicate::Error => {
544 if angle_open {
545 // impl Trait<X, {error}>
546 write!(f, ", ")?;
547 } else if !first {
548 // impl Trait + {error}
549 write!(f, " + ")?;
550 }
551 p.hir_fmt(f)?;
552 }
553 }
554 first = false;
555 }
556 if angle_open {
557 write!(f, ">")?;
558 }
559 Ok(())
560}
561
562impl TraitRef {
563 fn hir_fmt_ext(&self, f: &mut HirFormatter, use_as: bool) -> Result<(), HirDisplayError> {
564 if f.should_truncate() {
565 return write!(f, "{}", TYPE_HINT_TRUNCATION);
566 }
567
568 self.substs[0].hir_fmt(f)?;
569 if use_as {
570 write!(f, " as ")?;
571 } else {
572 write!(f, ": ")?;
573 }
574 write!(f, "{}", f.db.trait_data(self.trait_).name)?;
575 if self.substs.len() > 1 {
576 write!(f, "<")?;
577 f.write_joined(&self.substs[1..], ", ")?;
578 write!(f, ">")?;
579 }
580 Ok(())
581 }
582}
583
584impl HirDisplay for TraitRef {
585 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
586 self.hir_fmt_ext(f, false)
587 }
588}
589
590impl HirDisplay for &GenericPredicate {
591 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
592 HirDisplay::hir_fmt(*self, f)
593 }
594}
595
596impl HirDisplay for GenericPredicate {
597 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
598 if f.should_truncate() {
599 return write!(f, "{}", TYPE_HINT_TRUNCATION);
600 }
601
602 match self {
603 GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
604 GenericPredicate::Projection(projection_pred) => {
605 write!(f, "<")?;
606 projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
607 write!(
608 f,
609 ">::{} = {}",
610 f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name,
611 projection_pred.ty.display(f.db)
612 )?;
613 }
614 GenericPredicate::Error => write!(f, "{{error}}")?,
615 }
616 Ok(())
617 }
618}
619
620impl HirDisplay for Obligation {
621 fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
622 Ok(match self {
623 Obligation::Trait(tr) => write!(f, "Implements({})", tr.display(f.db))?,
624 Obligation::Projection(proj) => write!(
625 f,
626 "Normalize({} => {})",
627 proj.projection_ty.display(f.db),
628 proj.ty.display(f.db)
629 )?,
630 })
631 }
632}
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
new file mode 100644
index 000000000..03b00b101
--- /dev/null
+++ b/crates/hir_ty/src/infer.rs
@@ -0,0 +1,802 @@
1//! Type inference, i.e. the process of walking through the code and determining
2//! the type of each expression and pattern.
3//!
4//! For type inference, compare the implementations in rustc (the various
5//! check_* methods in librustc_typeck/check/mod.rs are a good entry point) and
6//! IntelliJ-Rust (org.rust.lang.core.types.infer). Our entry point for
7//! inference here is the `infer` function, which infers the types of all
8//! expressions in a given function.
9//!
10//! During inference, types (i.e. the `Ty` struct) can contain type 'variables'
11//! which represent currently unknown types; as we walk through the expressions,
12//! we might determine that certain variables need to be equal to each other, or
13//! to certain types. To record this, we use the union-find implementation from
14//! the `ena` crate, which is extracted from rustc.
15
16use std::borrow::Cow;
17use std::mem;
18use std::ops::Index;
19use std::sync::Arc;
20
21use arena::map::ArenaMap;
22use hir_def::{
23 body::Body,
24 data::{ConstData, FunctionData, StaticData},
25 expr::{BindingAnnotation, ExprId, PatId},
26 lang_item::LangItemTarget,
27 path::{path, Path},
28 resolver::{HasResolver, Resolver, TypeNs},
29 type_ref::{Mutability, TypeRef},
30 AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, FunctionId, Lookup, TraitId,
31 TypeAliasId, VariantId,
32};
33use hir_expand::{diagnostics::DiagnosticSink, name::name};
34use rustc_hash::FxHashMap;
35use stdx::impl_from;
36use syntax::SmolStr;
37
38use super::{
39 primitive::{FloatTy, IntTy},
40 traits::{Guidance, Obligation, ProjectionPredicate, Solution},
41 InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor, TypeWalk,
42};
43use crate::{
44 db::HirDatabase, infer::diagnostics::InferenceDiagnostic, lower::ImplTraitLoweringMode,
45};
46
47pub(crate) use unify::unify;
48
49macro_rules! ty_app {
50 ($ctor:pat, $param:pat) => {
51 crate::Ty::Apply(crate::ApplicationTy { ctor: $ctor, parameters: $param })
52 };
53 ($ctor:pat) => {
54 ty_app!($ctor, _)
55 };
56}
57
58mod unify;
59mod path;
60mod expr;
61mod pat;
62mod coerce;
63
64/// The entry point of type inference.
65pub(crate) fn infer_query(db: &dyn HirDatabase, def: DefWithBodyId) -> Arc<InferenceResult> {
66 let _p = profile::span("infer_query");
67 let resolver = def.resolver(db.upcast());
68 let mut ctx = InferenceContext::new(db, def, resolver);
69
70 match def {
71 DefWithBodyId::ConstId(c) => ctx.collect_const(&db.const_data(c)),
72 DefWithBodyId::FunctionId(f) => ctx.collect_fn(&db.function_data(f)),
73 DefWithBodyId::StaticId(s) => ctx.collect_static(&db.static_data(s)),
74 }
75
76 ctx.infer_body();
77
78 Arc::new(ctx.resolve_all())
79}
80
81#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
82enum ExprOrPatId {
83 ExprId(ExprId),
84 PatId(PatId),
85}
86impl_from!(ExprId, PatId for ExprOrPatId);
87
88/// Binding modes inferred for patterns.
89/// https://doc.rust-lang.org/reference/patterns.html#binding-modes
90#[derive(Copy, Clone, Debug, Eq, PartialEq)]
91enum BindingMode {
92 Move,
93 Ref(Mutability),
94}
95
96impl BindingMode {
97 pub fn convert(annotation: BindingAnnotation) -> BindingMode {
98 match annotation {
99 BindingAnnotation::Unannotated | BindingAnnotation::Mutable => BindingMode::Move,
100 BindingAnnotation::Ref => BindingMode::Ref(Mutability::Shared),
101 BindingAnnotation::RefMut => BindingMode::Ref(Mutability::Mut),
102 }
103 }
104}
105
106impl Default for BindingMode {
107 fn default() -> Self {
108 BindingMode::Move
109 }
110}
111
112/// A mismatch between an expected and an inferred type.
113#[derive(Clone, PartialEq, Eq, Debug, Hash)]
114pub struct TypeMismatch {
115 pub expected: Ty,
116 pub actual: Ty,
117}
118
119/// The result of type inference: A mapping from expressions and patterns to types.
120#[derive(Clone, PartialEq, Eq, Debug, Default)]
121pub struct InferenceResult {
122 /// For each method call expr, records the function it resolves to.
123 method_resolutions: FxHashMap<ExprId, FunctionId>,
124 /// For each field access expr, records the field it resolves to.
125 field_resolutions: FxHashMap<ExprId, FieldId>,
126 /// For each field in record literal, records the field it resolves to.
127 record_field_resolutions: FxHashMap<ExprId, FieldId>,
128 record_field_pat_resolutions: FxHashMap<PatId, FieldId>,
129 /// For each struct literal, records the variant it resolves to.
130 variant_resolutions: FxHashMap<ExprOrPatId, VariantId>,
131 /// For each associated item record what it resolves to
132 assoc_resolutions: FxHashMap<ExprOrPatId, AssocItemId>,
133 diagnostics: Vec<InferenceDiagnostic>,
134 pub type_of_expr: ArenaMap<ExprId, Ty>,
135 pub type_of_pat: ArenaMap<PatId, Ty>,
136 pub(super) type_mismatches: ArenaMap<ExprId, TypeMismatch>,
137}
138
139impl InferenceResult {
140 pub fn method_resolution(&self, expr: ExprId) -> Option<FunctionId> {
141 self.method_resolutions.get(&expr).copied()
142 }
143 pub fn field_resolution(&self, expr: ExprId) -> Option<FieldId> {
144 self.field_resolutions.get(&expr).copied()
145 }
146 pub fn record_field_resolution(&self, expr: ExprId) -> Option<FieldId> {
147 self.record_field_resolutions.get(&expr).copied()
148 }
149 pub fn record_field_pat_resolution(&self, pat: PatId) -> Option<FieldId> {
150 self.record_field_pat_resolutions.get(&pat).copied()
151 }
152 pub fn variant_resolution_for_expr(&self, id: ExprId) -> Option<VariantId> {
153 self.variant_resolutions.get(&id.into()).copied()
154 }
155 pub fn variant_resolution_for_pat(&self, id: PatId) -> Option<VariantId> {
156 self.variant_resolutions.get(&id.into()).copied()
157 }
158 pub fn assoc_resolutions_for_expr(&self, id: ExprId) -> Option<AssocItemId> {
159 self.assoc_resolutions.get(&id.into()).copied()
160 }
161 pub fn assoc_resolutions_for_pat(&self, id: PatId) -> Option<AssocItemId> {
162 self.assoc_resolutions.get(&id.into()).copied()
163 }
164 pub fn type_mismatch_for_expr(&self, expr: ExprId) -> Option<&TypeMismatch> {
165 self.type_mismatches.get(expr)
166 }
167 pub fn add_diagnostics(
168 &self,
169 db: &dyn HirDatabase,
170 owner: DefWithBodyId,
171 sink: &mut DiagnosticSink,
172 ) {
173 self.diagnostics.iter().for_each(|it| it.add_to(db, owner, sink))
174 }
175}
176
177impl Index<ExprId> for InferenceResult {
178 type Output = Ty;
179
180 fn index(&self, expr: ExprId) -> &Ty {
181 self.type_of_expr.get(expr).unwrap_or(&Ty::Unknown)
182 }
183}
184
185impl Index<PatId> for InferenceResult {
186 type Output = Ty;
187
188 fn index(&self, pat: PatId) -> &Ty {
189 self.type_of_pat.get(pat).unwrap_or(&Ty::Unknown)
190 }
191}
192
193/// The inference context contains all information needed during type inference.
194#[derive(Clone, Debug)]
195struct InferenceContext<'a> {
196 db: &'a dyn HirDatabase,
197 owner: DefWithBodyId,
198 body: Arc<Body>,
199 resolver: Resolver,
200 table: unify::InferenceTable,
201 trait_env: Arc<TraitEnvironment>,
202 obligations: Vec<Obligation>,
203 result: InferenceResult,
204 /// The return type of the function being inferred, or the closure if we're
205 /// currently within one.
206 ///
207 /// We might consider using a nested inference context for checking
208 /// closures, but currently this is the only field that will change there,
209 /// so it doesn't make sense.
210 return_ty: Ty,
211 diverges: Diverges,
212 breakables: Vec<BreakableContext>,
213}
214
215#[derive(Clone, Debug)]
216struct BreakableContext {
217 pub may_break: bool,
218 pub break_ty: Ty,
219 pub label: Option<name::Name>,
220}
221
222fn find_breakable<'c>(
223 ctxs: &'c mut [BreakableContext],
224 label: Option<&name::Name>,
225) -> Option<&'c mut BreakableContext> {
226 match label {
227 Some(_) => ctxs.iter_mut().rev().find(|ctx| ctx.label.as_ref() == label),
228 None => ctxs.last_mut(),
229 }
230}
231
232impl<'a> InferenceContext<'a> {
233 fn new(db: &'a dyn HirDatabase, owner: DefWithBodyId, resolver: Resolver) -> Self {
234 InferenceContext {
235 result: InferenceResult::default(),
236 table: unify::InferenceTable::new(),
237 obligations: Vec::default(),
238 return_ty: Ty::Unknown, // set in collect_fn_signature
239 trait_env: TraitEnvironment::lower(db, &resolver),
240 db,
241 owner,
242 body: db.body(owner),
243 resolver,
244 diverges: Diverges::Maybe,
245 breakables: Vec::new(),
246 }
247 }
248
249 fn resolve_all(mut self) -> InferenceResult {
250 // FIXME resolve obligations as well (use Guidance if necessary)
251 let mut result = std::mem::take(&mut self.result);
252 for ty in result.type_of_expr.values_mut() {
253 let resolved = self.table.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
254 *ty = resolved;
255 }
256 for ty in result.type_of_pat.values_mut() {
257 let resolved = self.table.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
258 *ty = resolved;
259 }
260 result
261 }
262
263 fn write_expr_ty(&mut self, expr: ExprId, ty: Ty) {
264 self.result.type_of_expr.insert(expr, ty);
265 }
266
267 fn write_method_resolution(&mut self, expr: ExprId, func: FunctionId) {
268 self.result.method_resolutions.insert(expr, func);
269 }
270
271 fn write_field_resolution(&mut self, expr: ExprId, field: FieldId) {
272 self.result.field_resolutions.insert(expr, field);
273 }
274
275 fn write_variant_resolution(&mut self, id: ExprOrPatId, variant: VariantId) {
276 self.result.variant_resolutions.insert(id, variant);
277 }
278
279 fn write_assoc_resolution(&mut self, id: ExprOrPatId, item: AssocItemId) {
280 self.result.assoc_resolutions.insert(id, item);
281 }
282
283 fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
284 self.result.type_of_pat.insert(pat, ty);
285 }
286
287 fn push_diagnostic(&mut self, diagnostic: InferenceDiagnostic) {
288 self.result.diagnostics.push(diagnostic);
289 }
290
291 fn make_ty_with_mode(
292 &mut self,
293 type_ref: &TypeRef,
294 impl_trait_mode: ImplTraitLoweringMode,
295 ) -> Ty {
296 // FIXME use right resolver for block
297 let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver)
298 .with_impl_trait_mode(impl_trait_mode);
299 let ty = Ty::from_hir(&ctx, type_ref);
300 let ty = self.insert_type_vars(ty);
301 self.normalize_associated_types_in(ty)
302 }
303
304 fn make_ty(&mut self, type_ref: &TypeRef) -> Ty {
305 self.make_ty_with_mode(type_ref, ImplTraitLoweringMode::Disallowed)
306 }
307
308 /// Replaces Ty::Unknown by a new type var, so we can maybe still infer it.
309 fn insert_type_vars_shallow(&mut self, ty: Ty) -> Ty {
310 match ty {
311 Ty::Unknown => self.table.new_type_var(),
312 _ => ty,
313 }
314 }
315
316 fn insert_type_vars(&mut self, ty: Ty) -> Ty {
317 ty.fold(&mut |ty| self.insert_type_vars_shallow(ty))
318 }
319
320 fn resolve_obligations_as_possible(&mut self) {
321 let obligations = mem::replace(&mut self.obligations, Vec::new());
322 for obligation in obligations {
323 let in_env = InEnvironment::new(self.trait_env.clone(), obligation.clone());
324 let canonicalized = self.canonicalizer().canonicalize_obligation(in_env);
325 let solution =
326 self.db.trait_solve(self.resolver.krate().unwrap(), canonicalized.value.clone());
327
328 match solution {
329 Some(Solution::Unique(substs)) => {
330 canonicalized.apply_solution(self, substs.0);
331 }
332 Some(Solution::Ambig(Guidance::Definite(substs))) => {
333 canonicalized.apply_solution(self, substs.0);
334 self.obligations.push(obligation);
335 }
336 Some(_) => {
337 // FIXME use this when trying to resolve everything at the end
338 self.obligations.push(obligation);
339 }
340