3 files changed, 373 insertions, 14 deletions

diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 209965fca..28b11cdde 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -1,7 +1,7 @@
 //! Transforms `ast::Expr` into an equivalent `hir_def::expr::Expr`
 //! representation.
 
-use std::{any::type_name, sync::Arc};
+use std::{any::type_name, mem, sync::Arc};
 
 use either::Either;
 use hir_expand::{
@@ -36,8 +36,8 @@ use crate::{
     item_tree::{ItemTree, ItemTreeId, ItemTreeNode},
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
-    AdtId, ConstLoc, ContainerId, DefWithBodyId, EnumLoc, FunctionLoc, Intern, ModuleDefId,
-    StaticLoc, StructLoc, TraitLoc, TypeAliasLoc, UnionLoc,
+    AdtId, BlockLoc, ConstLoc, ContainerId, DefWithBodyId, EnumLoc, FunctionLoc, Intern,
+    ModuleDefId, StaticLoc, StructLoc, TraitLoc, TypeAliasLoc, UnionLoc,
 };
 
 use super::{diagnostics::BodyDiagnostic, ExprSource, PatSource};
@@ -152,8 +152,8 @@ impl ExprCollector<'_> {
     fn alloc_expr_desugared(&mut self, expr: Expr) -> ExprId {
         self.make_expr(expr, Err(SyntheticSyntax))
     }
-    fn empty_block(&mut self) -> ExprId {
-        self.alloc_expr_desugared(Expr::Block { statements: Vec::new(), tail: None, label: None })
+    fn unit(&mut self) -> ExprId {
+        self.alloc_expr_desugared(Expr::Tuple { exprs: Vec::new() })
     }
     fn missing_expr(&mut self) -> ExprId {
         self.alloc_expr_desugared(Expr::Missing)
@@ -222,7 +222,7 @@ impl ExprCollector<'_> {
                                 MatchArm { pat, expr: then_branch, guard: None },
                                 MatchArm {
                                     pat: placeholder_pat,
-                                    expr: else_branch.unwrap_or_else(|| self.empty_block()),
+                                    expr: else_branch.unwrap_or_else(|| self.unit()),
                                     guard: None,
                                 },
                             ];
@@ -561,7 +561,7 @@ impl ExprCollector<'_> {
         let outer_file = self.expander.current_file_id;
 
         let macro_call = self.expander.to_source(AstPtr::new(&e));
-        let res = self.expander.enter_expand(self.db, Some(&self.body.item_scope), e);
+        let res = self.expander.enter_expand(self.db, e);
 
         match &res.err {
             Some(ExpandError::UnresolvedProcMacro) => {
@@ -697,12 +697,30 @@ impl ExprCollector<'_> {
     }
 
     fn collect_block(&mut self, block: ast::BlockExpr) -> ExprId {
-        let syntax_node_ptr = AstPtr::new(&block.clone().into());
+        let ast_id = self.expander.ast_id(&block);
+        let block_loc =
+            BlockLoc { ast_id, module: self.expander.def_map.module_id(self.expander.module) };
+        let block_id = self.db.intern_block(block_loc);
+        let opt_def_map = self.db.block_def_map(block_id);
+        let has_def_map = opt_def_map.is_some();
+        let def_map = opt_def_map.unwrap_or_else(|| self.expander.def_map.clone());
+        let module = if has_def_map { def_map.root() } else { self.expander.module };
+        let prev_def_map = mem::replace(&mut self.expander.def_map, def_map);
+        let prev_local_module = mem::replace(&mut self.expander.module, module);
+
         self.collect_stmts_items(block.statements());
         let statements =
             block.statements().filter_map(|s| self.collect_stmt(s)).flatten().collect();
         let tail = block.tail_expr().map(|e| self.collect_expr(e));
-        self.alloc_expr(Expr::Block { statements, tail, label: None }, syntax_node_ptr)
+        let syntax_node_ptr = AstPtr::new(&block.clone().into());
+        let expr_id = self.alloc_expr(
+            Expr::Block { id: block_id, statements, tail, label: None },
+            syntax_node_ptr,
+        );
+
+        self.expander.def_map = prev_def_map;
+        self.expander.module = prev_local_module;
+        expr_id
     }
 
     fn collect_stmts_items(&mut self, stmts: ast::AstChildren<ast::Stmt>) {
@@ -794,7 +812,7 @@ impl ExprCollector<'_> {
                 }
                 Either::Right(e) => {
                     let mac = MacroDefId {
-                        krate: self.expander.module.krate,
+                        krate: self.expander.def_map.krate(),
                         ast_id: Some(self.expander.ast_id(&e)),
                         kind: MacroDefKind::Declarative,
                         local_inner: false,
@@ -832,9 +850,9 @@ impl ExprCollector<'_> {
                 if annotation == BindingAnnotation::Unannotated && subpat.is_none() {
                     // This could also be a single-segment path pattern. To
                     // decide that, we need to try resolving the name.
-                    let (resolved, _) = self.expander.crate_def_map.resolve_path(
+                    let (resolved, _) = self.expander.def_map.resolve_path(
                         self.db,
-                        self.expander.module.local_id,
+                        self.expander.module,
                         &name.clone().into(),
                         BuiltinShadowMode::Other,
                     );
diff --git a/crates/hir_def/src/body/tests.rs b/crates/hir_def/src/body/tests.rs
index 2e5d0a01e..a92134ba7 100644
--- a/crates/hir_def/src/body/tests.rs
+++ b/crates/hir_def/src/body/tests.rs
@@ -1,7 +1,10 @@
-use base_db::{fixture::WithFixture, SourceDatabase};
+mod block;
+
+use base_db::{fixture::WithFixture, FilePosition, SourceDatabase};
+use expect_test::Expect;
 use test_utils::mark;
 
-use crate::{test_db::TestDB, ModuleDefId};
+use crate::{test_db::TestDB, BlockId, ModuleDefId};
 
 use super::*;
 
@@ -31,6 +34,114 @@ fn check_diagnostics(ra_fixture: &str) {
     db.check_diagnostics();
 }
 
+fn block_def_map_at(ra_fixture: &str) -> String {
+    let (db, position) = crate::test_db::TestDB::with_position(ra_fixture);
+
+    let krate = db.crate_graph().iter().next().unwrap();
+    let def_map = db.crate_def_map(krate);
+
+    let mut block =
+        block_at_pos(&db, &def_map, position).expect("couldn't find enclosing function or block");
+    loop {
+        let def_map = db.block_def_map(block).unwrap_or_else(|| def_map.clone());
+        let new_block = block_at_pos(&db, &def_map, position);
+        match new_block {
+            Some(new_block) => {
+                assert_ne!(block, new_block);
+                block = new_block;
+            }
+            None => {
+                return def_map.dump(&db);
+            }
+        }
+    }
+}
+
+fn block_at_pos(db: &dyn DefDatabase, def_map: &DefMap, position: FilePosition) -> Option<BlockId> {
+    // Find the smallest (innermost) function containing the cursor.
+    let mut size = None;
+    let mut fn_def = None;
+    for (_, module) in def_map.modules() {
+        let file_id = module.definition_source(db).file_id;
+        if file_id != position.file_id.into() {
+            continue;
+        }
+        let root = db.parse_or_expand(file_id).unwrap();
+        let ast_map = db.ast_id_map(file_id);
+        let item_tree = db.item_tree(file_id);
+        for decl in module.scope.declarations() {
+            if let ModuleDefId::FunctionId(it) = decl {
+                let ast = ast_map.get(item_tree[it.lookup(db).id.value].ast_id).to_node(&root);
+                let range = ast.syntax().text_range();
+
+                if !range.contains(position.offset) {
+                    continue;
+                }
+
+                let new_size = match size {
+                    None => range.len(),
+                    Some(size) => {
+                        if range.len() < size {
+                            range.len()
+                        } else {
+                            size
+                        }
+                    }
+                };
+                if size != Some(new_size) {
+                    size = Some(new_size);
+                    fn_def = Some(it);
+                }
+            }
+        }
+    }
+
+    let (body, source_map) = db.body_with_source_map(fn_def?.into());
+
+    // Now find the smallest encompassing block expression in the function body.
+    let mut size = None;
+    let mut block_id = None;
+    for (expr_id, expr) in body.exprs.iter() {
+        if let Expr::Block { id, .. } = expr {
+            if let Ok(ast) = source_map.expr_syntax(expr_id) {
+                if ast.file_id != position.file_id.into() {
+                    continue;
+                }
+
+                let root = db.parse_or_expand(ast.file_id).unwrap();
+                let ast = ast.value.to_node(&root);
+                let range = ast.syntax().text_range();
+
+                if !range.contains(position.offset) {
+                    continue;
+                }
+
+                let new_size = match size {
+                    None => range.len(),
+                    Some(size) => {
+                        if range.len() < size {
+                            range.len()
+                        } else {
+                            size
+                        }
+                    }
+                };
+                if size != Some(new_size) {
+                    size = Some(new_size);
+                    block_id = Some(*id);
+                }
+            }
+        }
+    }
+
+    Some(block_id.expect("can't find block containing cursor"))
+}
+
+fn check_at(ra_fixture: &str, expect: Expect) {
+    let actual = block_def_map_at(ra_fixture);
+    expect.assert_eq(&actual);
+}
+
 #[test]
 fn your_stack_belongs_to_me() {
     mark::check!(your_stack_belongs_to_me);
diff --git a/crates/hir_def/src/body/tests/block.rs b/crates/hir_def/src/body/tests/block.rs
new file mode 100644
index 000000000..062560a70
--- /dev/null
+++ b/crates/hir_def/src/body/tests/block.rs
@@ -0,0 +1,230 @@
+use super::*;
+use expect_test::expect;
+
+#[test]
+fn inner_item_smoke() {
+    check_at(
+        r#"
+struct inner {}
+fn outer() {
+    $0
+    fn inner() {}
+}
+"#,
+        expect![[r#"
+            block scope
+            inner: v
+
+            crate
+            inner: t
+            outer: v
+        "#]],
+    );
+}
+
+#[test]
+fn use_from_crate() {
+    check_at(
+        r#"
+struct Struct;
+fn outer() {
+    use Struct;
+    use crate::Struct as CrateStruct;
+    use self::Struct as SelfStruct;
+    $0
+}
+"#,
+        expect![[r#"
+            block scope
+            CrateStruct: t v
+            SelfStruct: t v
+            Struct: t v
+
+            crate
+            Struct: t v
+            outer: v
+        "#]],
+    );
+}
+
+#[test]
+fn merge_namespaces() {
+    check_at(
+        r#"
+struct name {}
+fn outer() {
+    fn name() {}
+
+    use name as imported; // should import both `name`s
+
+    $0
+}
+"#,
+        expect![[r#"
+            block scope
+            imported: t v
+            name: v
+
+            crate
+            name: t
+            outer: v
+        "#]],
+    );
+}
+
+#[test]
+fn nested_blocks() {
+    check_at(
+        r#"
+fn outer() {
+    struct inner1 {}
+    fn inner() {
+        use inner1;
+        use outer;
+        fn inner2() {}
+        $0
+    }
+}
+"#,
+        expect![[r#"
+            block scope
+            inner1: t
+            inner2: v
+            outer: v
+
+            block scope
+            inner: v
+            inner1: t
+
+            crate
+            outer: v
+        "#]],
+    );
+}
+
+#[test]
+fn super_imports() {
+    check_at(
+        r#"
+mod module {
+    fn f() {
+        use super::Struct;
+        $0
+    }
+}
+
+struct Struct {}
+"#,
+        expect![[r#"
+            block scope
+            Struct: t
+
+            crate
+            Struct: t
+            module: t
+
+            crate::module
+            f: v
+        "#]],
+    );
+}
+
+#[test]
+fn legacy_macro_items() {
+    // Checks that legacy-scoped `macro_rules!` from parent namespaces are resolved and expanded
+    // correctly.
+    check_at(
+        r#"
+macro_rules! hit {
+    () => {
+        struct Hit {}
+    }
+}
+
+fn f() {
+    hit!();
+    $0
+}
+"#,
+        expect![[r#"
+            block scope
+            Hit: t
+
+            crate
+            f: v
+        "#]],
+    );
+}
+
+#[test]
+fn macro_resolve() {
+    check_at(
+        r#"
+//- /lib.rs crate:lib deps:core
+use core::mark;
+
+fn f() {
+    fn nested() {
+        mark::hit!(Hit);
+        $0
+    }
+}
+//- /core.rs crate:core
+pub mod mark {
+    #[macro_export]
+    macro_rules! _hit {
+        ($name:ident) => {
+            struct $name {}
+        }
+    }
+
+    pub use crate::_hit as hit;
+}
+"#,
+        expect![[r#"
+            block scope
+            Hit: t
+
+            block scope
+            nested: v
+
+            crate
+            f: v
+            mark: t
+        "#]],
+    );
+}
+
+#[test]
+fn macro_resolve_legacy() {
+    check_at(
+        r#"
+//- /lib.rs
+mod module;
+
+//- /module.rs
+macro_rules! m {
+    () => {
+        struct Def {}
+    };
+}
+
+fn f() {
+    {
+        m!();
+        $0
+    }
+}
+        "#,
+        expect![[r#"
+            block scope
+            Def: t
+
+            crate
+            module: t
+
+            crate::module
+            f: v
+        "#]],
+    )
+}