allow normal dotted names

crates/ruff_python_parser/resources/inline/ok/decorator_expression_dotted_ident_before_py39.py

@@ -0,0 +1,3 @@
+# parse_options: { "target_version": "3.8" }
+@buttons.clicked.connect
+def spam(): ...

crates/ruff_python_parser/src/parser/statement.rs

@@ -2530,11 +2530,25 @@ impl<'src> Parser<'src> {
     fn try_parse_old_decorators(&mut self) -> Option<ParsedExpr> {
         let errors = self.errors.len();
         let start = self.node_start();
-        let name = self.parse_name();
-        if name.ctx.is_invalid() {
+        // initial identifier
+        let ident = self.parse_identifier();
+        if !ident.is_valid() {
             return None;
         }
-        let name = Expr::from(name);
+        let mut name = Expr::from(ast::ExprName {
+            range: self.node_range(start),
+            id: ident.id,
+            ctx: ExprContext::Load,
+        });
+        // ("." identifier)*
+        while self.at(TokenKind::Dot) {
+            let attr = self.parse_attribute_expression(name, start);
+            if !attr.attr.is_valid() {
+                return None;
+            }
+            name = Expr::from(attr);
+        }
+        // ["(" [argument_list [","]] ")"] NEWLINE
         let parsed = match self.current_token_kind() {
             TokenKind::Lpar => Some(Expr::Call(self.parse_call_expression(name, start)).into()),
             TokenKind::Newline => Some(name.into()),
@@ -2564,6 +2578,11 @@ impl<'src> Parser<'src> {
         // before 3.9 but avoid false positives on examples like the `@_` "identity function hack"
         // or the "eval hack" called out in the PEP.
 
+        // test_ok decorator_expression_dotted_ident_before_py39
+        // # parse_options: { "target_version": "3.8" }
+        // @buttons.clicked.connect
+        // def spam(): ...
+
         // test_ok decorator_expression_identity_hack_before_py39
         // # parse_options: { "target_version": "3.8" }
         // def _(x): return x

crates/ruff_python_parser/tests/snapshots/valid_syntax@decorator_expression_dotted_ident_before_py39.py.snap

@@ -0,0 +1,79 @@
+---
+source: crates/ruff_python_parser/tests/fixtures.rs
+input_file: crates/ruff_python_parser/resources/inline/ok/decorator_expression_dotted_ident_before_py39.py
+---
+## AST
+
+```
+Module(
+    ModModule {
+        range: 0..86,
+        body: [
+            FunctionDef(
+                StmtFunctionDef {
+                    range: 45..85,
+                    is_async: false,
+                    decorator_list: [
+                        Decorator {
+                            range: 45..69,
+                            expression: Attribute(
+                                ExprAttribute {
+                                    range: 46..69,
+                                    value: Attribute(
+                                        ExprAttribute {
+                                            range: 46..61,
+                                            value: Name(
+                                                ExprName {
+                                                    range: 46..53,
+                                                    id: Name("buttons"),
+                                                    ctx: Load,
+                                                },
+                                            ),
+                                            attr: Identifier {
+                                                id: Name("clicked"),
+                                                range: 54..61,
+                                            },
+                                            ctx: Load,
+                                        },
+                                    ),
+                                    attr: Identifier {
+                                        id: Name("connect"),
+                                        range: 62..69,
+                                    },
+                                    ctx: Load,
+                                },
+                            ),
+                        },
+                    ],
+                    name: Identifier {
+                        id: Name("spam"),
+                        range: 74..78,
+                    },
+                    type_params: None,
+                    parameters: Parameters {
+                        range: 78..80,
+                        posonlyargs: [],
+                        args: [],
+                        vararg: None,
+                        kwonlyargs: [],
+                        kwarg: None,
+                    },
+                    returns: None,
+                    body: [
+                        Expr(
+                            StmtExpr {
+                                range: 82..85,
+                                value: EllipsisLiteral(
+                                    ExprEllipsisLiteral {
+                                        range: 82..85,
+                                    },
+                                ),
+                            },
+                        ),
+                    ],
+                },
+            ),
+        ],
+    },
+)
+```