3 files changed, 228 insertions, 3 deletions

diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
index 09a39e721..10cb87d37 100644
--- a/crates/ra_hir_def/src/body/scope.rs
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -67,6 +67,11 @@ impl ExprScopes {
         std::iter::successors(scope, move |&scope| self.scopes[scope].parent)
     }
 
+    pub fn resolve_name_in_scope(&self, scope: ScopeId, name: &Name) -> Option<&ScopeEntry> {
+        self.scope_chain(Some(scope))
+            .find_map(|scope| self.entries(scope).iter().find(|it| it.name == *name))
+    }
+
     pub fn scope_for(&self, expr: ExprId) -> Option<ScopeId> {
         self.scope_by_expr.get(&expr).copied()
     }
@@ -163,3 +168,217 @@ fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope
         e => e.walk_child_exprs(|e| compute_expr_scopes(e, body, scopes, scope)),
     };
 }
+
+#[cfg(test)]
+mod tests {
+    use hir_expand::{name::AsName, Source};
+    use ra_db::{fixture::WithFixture, FileId, SourceDatabase};
+    use ra_syntax::{algo::find_node_at_offset, ast, AstNode};
+    use test_utils::{assert_eq_text, extract_offset};
+
+    use crate::{db::DefDatabase2, test_db::TestDB, FunctionId, ModuleDefId};
+
+    fn find_function(db: &TestDB, file_id: FileId) -> FunctionId {
+        let krate = db.test_crate();
+        let crate_def_map = db.crate_def_map(krate);
+
+        let module = crate_def_map.modules_for_file(file_id).next().unwrap();
+        let (_, res) = crate_def_map[module].scope.entries().next().unwrap();
+        match res.def.take_values().unwrap() {
+            ModuleDefId::FunctionId(it) => it,
+            _ => panic!(),
+        }
+    }
+
+    fn do_check(code: &str, expected: &[&str]) {
+        let (off, code) = extract_offset(code);
+        let code = {
+            let mut buf = String::new();
+            let off = u32::from(off) as usize;
+            buf.push_str(&code[..off]);
+            buf.push_str("marker");
+            buf.push_str(&code[off..]);
+            buf
+        };
+
+        let (db, file_id) = TestDB::with_single_file(&code);
+
+        let file_syntax = db.parse(file_id).syntax_node();
+        let marker: ast::PathExpr = find_node_at_offset(&file_syntax, off).unwrap();
+        let function = find_function(&db, file_id);
+
+        let scopes = db.expr_scopes(function.into());
+        let (_body, source_map) = db.body_with_source_map(function.into());
+
+        let expr_id =
+            source_map.node_expr(Source { file_id: file_id.into(), ast: &marker.into() }).unwrap();
+        let scope = scopes.scope_for(expr_id);
+
+        let actual = scopes
+            .scope_chain(scope)
+            .flat_map(|scope| scopes.entries(scope))
+            .map(|it| it.name().to_string())
+            .collect::<Vec<_>>()
+            .join("\n");
+        let expected = expected.join("\n");
+        assert_eq_text!(&expected, &actual);
+    }
+
+    #[test]
+    fn test_lambda_scope() {
+        do_check(
+            r"
+            fn quux(foo: i32) {
+                let f = |bar, baz: i32| {
+                    <|>
+                };
+            }",
+            &["bar", "baz", "foo"],
+        );
+    }
+
+    #[test]
+    fn test_call_scope() {
+        do_check(
+            r"
+            fn quux() {
+                f(|x| <|> );
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_method_call_scope() {
+        do_check(
+            r"
+            fn quux() {
+                z.f(|x| <|> );
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_loop_scope() {
+        do_check(
+            r"
+            fn quux() {
+                loop {
+                    let x = ();
+                    <|>
+                };
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_match() {
+        do_check(
+            r"
+            fn quux() {
+                match () {
+                    Some(x) => {
+                        <|>
+                    }
+                };
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_shadow_variable() {
+        do_check(
+            r"
+            fn foo(x: String) {
+                let x : &str = &x<|>;
+            }",
+            &["x"],
+        );
+    }
+
+    fn do_check_local_name(code: &str, expected_offset: u32) {
+        let (off, code) = extract_offset(code);
+
+        let (db, file_id) = TestDB::with_single_file(&code);
+
+        let file = db.parse(file_id).ok().unwrap();
+        let expected_name = find_node_at_offset::<ast::Name>(file.syntax(), expected_offset.into())
+            .expect("failed to find a name at the target offset");
+        let name_ref: ast::NameRef = find_node_at_offset(file.syntax(), off).unwrap();
+
+        let function = find_function(&db, file_id);
+
+        let scopes = db.expr_scopes(function.into());
+        let (_body, source_map) = db.body_with_source_map(function.into());
+
+        let expr_scope = {
+            let expr_ast = name_ref.syntax().ancestors().find_map(ast::Expr::cast).unwrap();
+            let expr_id =
+                source_map.node_expr(Source { file_id: file_id.into(), ast: &expr_ast }).unwrap();
+            scopes.scope_for(expr_id).unwrap()
+        };
+
+        let resolved = scopes.resolve_name_in_scope(expr_scope, &name_ref.as_name()).unwrap();
+        let pat_src = source_map.pat_syntax(resolved.pat()).unwrap();
+
+        let local_name = pat_src.ast.either(|it| it.syntax_node_ptr(), |it| it.syntax_node_ptr());
+        assert_eq!(local_name.range(), expected_name.syntax().text_range());
+    }
+
+    #[test]
+    fn test_resolve_local_name() {
+        do_check_local_name(
+            r#"
+            fn foo(x: i32, y: u32) {
+                {
+                    let z = x * 2;
+                }
+                {
+                    let t = x<|> * 3;
+                }
+            }"#,
+            21,
+        );
+    }
+
+    #[test]
+    fn test_resolve_local_name_declaration() {
+        do_check_local_name(
+            r#"
+            fn foo(x: String) {
+                let x : &str = &x<|>;
+            }"#,
+            21,
+        );
+    }
+
+    #[test]
+    fn test_resolve_local_name_shadow() {
+        do_check_local_name(
+            r"
+            fn foo(x: String) {
+                let x : &str = &x;
+                x<|>
+            }
+            ",
+            53,
+        );
+    }
+
+    #[test]
+    fn ref_patterns_contribute_bindings() {
+        do_check_local_name(
+            r"
+            fn foo() {
+                if let Some(&from) = bar() {
+                    from<|>;
+                }
+            }
+            ",
+            53,
+        );
+    }
+}
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index 5fc592150..21d5f62e0 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -58,7 +58,7 @@ mod tests;
 
 use std::sync::Arc;
 
-use hir_expand::{diagnostics::DiagnosticSink, name::Name, MacroDefId};
+use hir_expand::{ast_id_map::FileAstId, diagnostics::DiagnosticSink, name::Name, MacroDefId};
 use once_cell::sync::Lazy;
 use ra_arena::Arena;
 use ra_db::{CrateId, Edition, FileId};
@@ -73,7 +73,7 @@ use crate::{
         diagnostics::DefDiagnostic, path_resolution::ResolveMode, per_ns::PerNs, raw::ImportId,
     },
     path::Path,
-    AstId, CrateModuleId, ModuleDefId, ModuleId, TraitId,
+    AstId, CrateModuleId, FunctionId, ModuleDefId, ModuleId, TraitId,
 };
 
 /// Contains all top-level defs from a macro-expanded crate
@@ -124,6 +124,11 @@ pub struct ModuleData {
     pub definition: Option<FileId>,
 }
 
+#[derive(Default, Debug, PartialEq, Eq, Clone)]
+pub(crate) struct Declarations {
+    fns: FxHashMap<FileAstId<ast::FnDef>, FunctionId>,
+}
+
 #[derive(Debug, Default, PartialEq, Eq, Clone)]
 pub struct ModuleScope {
     pub items: FxHashMap<Name, Resolution>,
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 83eef821f..5c899aff3 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -664,7 +664,8 @@ where
         let name = def.name.clone();
         let def: PerNs = match def.kind {
             raw::DefKind::Function(ast_id) => {
-                PerNs::values(FunctionId::from_ast_id(ctx, ast_id).into())
+                let f = FunctionId::from_ast_id(ctx, ast_id);
+                PerNs::values(f.into())
             }
             raw::DefKind::Struct(ast_id) => {
                 let id = StructOrUnionId::from_ast_id(ctx, ast_id).into();