Merge #4497

4497: Create LowerCtx on the fly r=matklad a=edwin0cheng

Previously we create `LowerCtx` at the beginning of lowering, however, the hygiene content is in fact changing between macro expression expanding. 

This PR change it to create the `LowerCtx` on the fly to fix above bug.

However, #4465 is not fixed by this PR, the goto-def is still not work yet. It only fixed the infer part. 

Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>

crates/ra_hir_def/src/body/lower.rs

@@ -60,13 +60,10 @@ pub(super) fn lower(
     params: Option<ast::ParamList>,
     body: Option<ast::Expr>,
 ) -> (Body, BodySourceMap) {
-    let ctx = LowerCtx::new(db, expander.current_file_id.clone());
-
     ExprCollector {
         db,
         def,
         expander,
-        ctx,
         source_map: BodySourceMap::default(),
         body: Body {
             exprs: Arena::default(),
@@ -83,7 +80,6 @@ struct ExprCollector<'a> {
     db: &'a dyn DefDatabase,
     def: DefWithBodyId,
     expander: Expander,
-    ctx: LowerCtx,
     body: Body,
     source_map: BodySourceMap,
 }
@@ -122,6 +118,10 @@ fn collect(
         (self.body, self.source_map)
     }
 
+    fn ctx(&self) -> LowerCtx {
+        LowerCtx::new(self.db, self.expander.current_file_id)
+    }
+
     fn alloc_expr(&mut self, expr: Expr, ptr: AstPtr<ast::Expr>) -> ExprId {
         let src = self.expander.to_source(ptr);
         let id = self.make_expr(expr, Ok(src.clone()));
@@ -268,7 +268,7 @@ fn collect_expr(&mut self, expr: ast::Expr) -> ExprId {
                 };
                 let method_name = e.name_ref().map(|nr| nr.as_name()).unwrap_or_else(Name::missing);
                 let generic_args =
-                    e.type_arg_list().and_then(|it| GenericArgs::from_ast(&self.ctx, it));
+                    e.type_arg_list().and_then(|it| GenericArgs::from_ast(&self.ctx(), it));
                 self.alloc_expr(
                     Expr::MethodCall { receiver, method_name, args, generic_args },
                     syntax_ptr,
@@ -373,7 +373,7 @@ fn collect_expr(&mut self, expr: ast::Expr) -> ExprId {
             }
             ast::Expr::CastExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
-                let type_ref = TypeRef::from_ast_opt(&self.ctx, e.type_ref());
+                let type_ref = TypeRef::from_ast_opt(&self.ctx(), e.type_ref());
                 self.alloc_expr(Expr::Cast { expr, type_ref }, syntax_ptr)
             }
             ast::Expr::RefExpr(e) => {
@@ -396,7 +396,7 @@ fn collect_expr(&mut self, expr: ast::Expr) -> ExprId {
                     for param in pl.params() {
                         let pat = self.collect_pat_opt(param.pat());
                         let type_ref =
-                            param.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx, it));
+                            param.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx(), it));
                         args.push(pat);
                         arg_types.push(type_ref);
                     }
@@ -404,7 +404,7 @@ fn collect_expr(&mut self, expr: ast::Expr) -> ExprId {
                 let ret_type = e
                     .ret_type()
                     .and_then(|r| r.type_ref())
-                    .map(|it| TypeRef::from_ast(&self.ctx, it));
+                    .map(|it| TypeRef::from_ast(&self.ctx(), it));
                 let body = self.collect_expr_opt(e.body());
                 self.alloc_expr(Expr::Lambda { args, arg_types, ret_type, body }, syntax_ptr)
             }
@@ -507,7 +507,8 @@ fn collect_block(&mut self, block: ast::BlockExpr) -> ExprId {
             .map(|s| match s {
                 ast::Stmt::LetStmt(stmt) => {
                     let pat = self.collect_pat_opt(stmt.pat());
-                    let type_ref = stmt.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx, it));
+                    let type_ref =
+                        stmt.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx(), it));
                     let initializer = stmt.initializer().map(|e| self.collect_expr(e));
                     Statement::Let { pat, type_ref, initializer }
                 }

crates/ra_hir_ty/src/tests/regression.rs

@@ -563,6 +563,37 @@ fn main() {
     );
 }
 
+#[test]
+fn issue_4465_dollar_crate_at_type() {
+    assert_snapshot!(
+        infer(r#"
+pub struct Foo {}
+pub fn anything<T>() -> T {
+    loop {}
+}
+macro_rules! foo {
+    () => {{
+        let r: $crate::Foo = anything();
+        r
+    }};
+}
+fn main() {
+    let _a = foo!();
+}
+"#), @r###"
+    45..60 '{     loop {} }': T
+    51..58 'loop {}': !
+    56..58 '{}': ()
+    !0..31 '{letr:...g();r}': Foo
+    !4..5 'r': Foo
+    !18..26 'anything': fn anything<Foo>() -> Foo
+    !18..28 'anything()': Foo
+    !29..30 'r': Foo
+    164..188 '{     ...!(); }': ()
+    174..176 '_a': Foo
+"###);
+}
+
 #[test]
 fn issue_4053_diesel_where_clauses() {
     assert_snapshot!(