Improve type check

crates/hir-analysis/src/ty/ty_check/env.rs

@@ -334,7 +334,7 @@ impl<'db> BlockEnv<'db> {
 pub struct ExprProp<'db> {
     pub ty: TyId<'db>,
     pub is_mut: bool,
-    pub(crate) binding: Option<LocalBinding<'db>>,
+    pub binding: Option<LocalBinding<'db>>,
 }
 
 impl<'db> ExprProp<'db> {
@@ -371,8 +371,9 @@ impl<'db> ExprProp<'db> {
     }
 }
 
+/// Represents a definition site of a local variable.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub(crate) enum LocalBinding<'db> {
+pub enum LocalBinding<'db> {
     Local {
         pat: PatId,
         is_mut: bool,

crates/hir-analysis/src/ty/ty_check/mod.rs

@@ -8,15 +8,14 @@ mod stmt;
 
 pub use callable::Callable;
 pub use env::ExprProp;
-use env::TyCheckEnv;
+use env::{LocalBinding, TyCheckEnv};
 pub(super) use expr::TraitOps;
 use hir::{
     hir_def::{Body, Expr, ExprId, Func, LitKind, Pat, PatId, PathId, TypeId as HirTyId},
     span::{expr::LazyExprSpan, pat::LazyPatSpan, DynLazySpan},
     visitor::{walk_expr, walk_pat, Visitor, VisitorCtxt},
 };
 pub(super) use path::RecordLike;
-
 use rustc_hash::{FxHashMap, FxHashSet};
 
 use super::{
@@ -234,13 +233,26 @@ impl<'db> TypedBody<'db> {
             .unwrap_or_else(|| ExprProp::invalid(db))
     }
 
+    /// Returns a local variable binding information.
+    /// Returns `None` if
+    /// * Expression is not a local variable, or
+    /// * Binding is missing in a user code.
+    pub fn binding_for(&self, expr: ExprId) -> Option<LocalBinding<'db>> {
+        let expr_prop = self.expr_ty.get(&expr)?;
+        expr_prop.binding
+    }
+
     pub fn pat_ty(&self, db: &'db dyn HirAnalysisDb, pat: PatId) -> TyId<'db> {
         self.pat_ty
             .get(&pat)
             .copied()
             .unwrap_or_else(|| TyId::invalid(db, InvalidCause::Other))
     }
 
+    /// Returns the callee information.
+    /// Returns `None` if
+    /// * the given `expr` is not a call or method call,  or
+    /// * the given `expr` isn't typed properly.
     pub fn callable_expr(&self, expr: ExprId) -> Option<&Callable<'db>> {
         self.callables.get(&expr)
     }