ignore type aliases in pyrefly report #3150

Author: jorenham

pyrefly/lib/commands/report.rs

@@ -507,7 +507,20 @@ impl ReportArgs {
                 _ => continue,
             };
             match binding {
-                BindingExport::AnnotatedForward(annot_idx, _) => {
+                BindingExport::AnnotatedForward(annot_idx, key_idx) => {
+                    // IMPLICIT: type aliases are type-level constructs with 0 slots.
+                    if matches!(
+                        bindings.get(*key_idx),
+                        Binding::TypeAlias(_) | Binding::TypeAliasRef(_)
+                    ) {
+                        variables.push(Variable {
+                            name: qualified_name,
+                            annotation: None,
+                            slots: SlotCounts::default(),
+                            location,
+                        });
+                        continue;
+                    }
                     let annotation_text = match bindings.get(*annot_idx) {
                         BindingAnnotation::AnnotateExpr(_, expr, _) => {
                             Some(module.code_at(expr.range()).to_owned())
@@ -531,8 +544,12 @@ impl ReportArgs {
                     match bindings.get(*idx) {
                         // Skip injected implicit globals
                         Binding::Global(_) => {}
-                        // IMPLICIT: special type forms have 0 slots
-                        Binding::TypeVar(_) | Binding::ParamSpec(_) | Binding::TypeVarTuple(_) => {
+                        // IMPLICIT: special type forms and type aliases have 0 slots
+                        Binding::TypeVar(_)
+                        | Binding::ParamSpec(_)
+                        | Binding::TypeVarTuple(_)
+                        | Binding::TypeAlias(_)
+                        | Binding::TypeAliasRef(_) => {
                             variables.push(Variable {
                                 name: qualified_name,
                                 annotation: None,
@@ -2248,4 +2265,12 @@ mod tests {
         let report = build_module_report_for_test("partial_any.py");
         compare_snapshot("partial_any.expected.json", &report);
     }
+
+    /// Type aliases (explicit `TypeAlias`, bare assignments, PEP 695, TypeAliasType)
+    /// are type-level constructs and should have 0 typable slots.
+    #[test]
+    fn test_report_type_aliases() {
+        let report = build_module_report_for_test("type_aliases.py");
+        compare_snapshot("type_aliases.expected.json", &report);
+    }
 }

pyrefly/lib/test/report/test_files/type_aliases.expected.json

@@ -0,0 +1,127 @@
+{
+  "name": "test",
+  "names": [
+    "test.T",
+    "test.Alias1",
+    "test.Alias2",
+    "test.Alias3",
+    "test.x",
+    "test.y",
+    "test.some_func",
+    "test.SomeClass"
+  ],
+  "line_count": 30,
+  "symbol_reports": [
+    {
+      "kind": "attr",
+      "name": "test.T",
+      "n_typable": 0,
+      "n_typed": 0,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 8,
+        "column": 1
+      }
+    },
+    {
+      "kind": "attr",
+      "name": "test.Alias1",
+      "n_typable": 0,
+      "n_typed": 0,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 11,
+        "column": 1
+      }
+    },
+    {
+      "kind": "attr",
+      "name": "test.Alias2",
+      "n_typable": 0,
+      "n_typed": 0,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 14,
+        "column": 1
+      }
+    },
+    {
+      "kind": "attr",
+      "name": "test.Alias3",
+      "n_typable": 0,
+      "n_typed": 0,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 17,
+        "column": 1
+      }
+    },
+    {
+      "kind": "attr",
+      "name": "test.x",
+      "n_typable": 1,
+      "n_typed": 1,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 20,
+        "column": 1
+      }
+    },
+    {
+      "kind": "attr",
+      "name": "test.y",
+      "n_typable": 1,
+      "n_typed": 1,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 21,
+        "column": 1
+      }
+    },
+    {
+      "kind": "function",
+      "name": "test.some_func",
+      "n_typable": 1,
+      "n_typed": 1,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 24,
+        "column": 1
+      }
+    },
+    {
+      "kind": "class",
+      "name": "test.SomeClass",
+      "n_typable": 0,
+      "n_typed": 0,
+      "n_any": 0,
+      "n_untyped": 0,
+      "location": {
+        "line": 28,
+        "column": 1
+      }
+    }
+  ],
+  "type_ignores": [],
+  "n_typable": 3,
+  "n_typed": 3,
+  "n_any": 0,
+  "n_untyped": 0,
+  "coverage": 100.0,
+  "strict_coverage": 100.0,
+  "n_functions": 1,
+  "n_methods": 0,
+  "n_function_params": 0,
+  "n_method_params": 0,
+  "n_classes": 1,
+  "n_attrs": 6,
+  "n_properties": 0,
+  "n_type_ignores": 0
+}

pyrefly/lib/test/report/test_files/type_aliases.py

@@ -0,0 +1,29 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import TypeAlias, TypeAliasType, TypeVar
+
+T = TypeVar("T")
+
+# Implicit type alias (bare assignment with recognizable type RHS)
+Alias1 = list[int]
+
+# Explicit TypeAlias annotation (legacy form)
+Alias2: TypeAlias = int | str
+
+# TypeAliasType call (runtime equivalent of PEP 695)
+Alias3 = TypeAliasType("Alias3", int)
+
+# Regular typed variable for baseline comparison
+x: int = 42
+y: type[int] = int
+
+
+def some_func() -> None:
+    pass
+
+
+class SomeClass:
+    my_field = 42