Support forward references in type aliases

Summary: Based on the conformance tests, forward references should be supported in scoped and explicit type aliases, but not in implicit type aliases. For explicit type aliases, we unfortunately have to match on the "TypeAlias" name. Reviewed By: samwgoldman, ndmitchell Differential Revision: D66318809 fbshipit-source-id: ef8419e63006803f02f708e60608e6d5132366e1
facebook · Nov 22, 2024 · 6596a92 · 6596a92
1 parent 1e30ddc
commit 6596a92
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diff --git a/pyre2/conformance/third_party/conformance.exp b/pyre2/conformance/third_party/conformance.exp
@@ -966,36 +966,6 @@
       "name": "PyreError",
       "stop_column": 32,
       "stop_line": 69
-    },
-    {
-      "code": -2,
-      "column": 35,
-      "concise_description": "untype, got Literal['RecursiveUnion']",
-      "description": "untype, got Literal['RecursiveUnion']",
-      "line": 72,
-      "name": "PyreError",
-      "stop_column": 51,
-      "stop_line": 72
-    },
-    {
-      "code": -2,
-      "column": 37,
-      "concise_description": "untype, got Literal['MutualReference2']",
-      "description": "untype, got Literal['MutualReference2']",
-      "line": 75,
-      "name": "PyreError",
-      "stop_column": 55,
-      "stop_line": 75
-    },
-    {
-      "code": -2,
-      "column": 99,
-      "concise_description": "untype, got Literal['MutualReference1']",
-      "description": "untype, got Literal['MutualReference1']",
-      "line": 75,
-      "name": "PyreError",
-      "stop_column": 117,
-      "stop_line": 75
     }
   ],
   "aliases_type_statement.py": [
@@ -1089,6 +1059,16 @@
       "stop_column": 30,
       "stop_line": 23
     },
+    {
+      "code": -2,
+      "column": 27,
+      "concise_description": "Could not parse type string: , got Expected an expression at byte range 791..791",
+      "description": "Could not parse type string: , got Expected an expression at byte range 791..791",
+      "line": 37,
+      "name": "PyreError",
+      "stop_column": 29,
+      "stop_line": 37
+    },
     {
       "code": -2,
       "column": 27,
@@ -1171,22 +1151,32 @@
     },
     {
       "code": -2,
-      "column": 42,
-      "concise_description": "Expected 0 positional argument(s)",
-      "description": "Expected 0 positional argument(s)",
-      "line": 40,
+      "column": 1,
+      "concise_description": "Expected `BadTypeAlias5` to be a type alias, got dict[Error, Error]",
+      "description": "Expected `BadTypeAlias5` to be a type alias, got dict[Error, Error]",
+      "line": 41,
       "name": "PyreError",
-      "stop_column": 43,
-      "stop_line": 40
+      "stop_column": 32,
+      "stop_line": 41
     },
     {
       "code": -2,
-      "column": 1,
-      "concise_description": "Expected `BadTypeAlias5` to be a type alias, got dict[str, str]",
-      "description": "Expected `BadTypeAlias5` to be a type alias, got dict[str, str]",
+      "column": 23,
+      "concise_description": "Could not find name `a`",
+      "description": "Could not find name `a`",
       "line": 41,
       "name": "PyreError",
-      "stop_column": 32,
+      "stop_column": 24,
+      "stop_line": 41
+    },
+    {
+      "code": -2,
+      "column": 28,
+      "concise_description": "Could not find name `b`",
+      "description": "Could not find name `b`",
+      "line": 41,
+      "name": "PyreError",
+      "stop_column": 29,
       "stop_line": 41
     },
     {

diff --git a/pyre2/conformance/third_party/conformance.result b/pyre2/conformance/third_party/conformance.result
@@ -68,6 +68,8 @@
     "Line 50: Expected 1 errors",
     "Line 51: Expected 1 errors",
     "Line 52: Expected 1 errors",
+    "Line 72: Expected 1 errors",
+    "Line 75: Expected 1 errors",
     "Line 14: Unexpected errors [\"untype, got Literal['Json']\", \"untype, got Literal['Json']\"]",
     "Line 24: Unexpected errors [\"untype, got Literal['Json2']\", \"untype, got Literal['Json2']\"]",
     "Line 30: Unexpected errors [\"untype, got Literal['RecursiveTuple']\"]",

diff --git a/pyre2/conformance/third_party/results.json b/pyre2/conformance/third_party/results.json
@@ -3,7 +3,7 @@
   "pass": 7,
   "fail": 126,
   "pass_rate": 0.05,
-  "differences": 1489,
+  "differences": 1491,
   "passing": [
     "directives_no_type_check.py",
     "directives_type_ignore.py",
@@ -17,7 +17,7 @@
     "aliases_explicit.py": 19,
     "aliases_implicit.py": 25,
     "aliases_newtype.py": 10,
-    "aliases_recursive.py": 17,
+    "aliases_recursive.py": 19,
     "aliases_type_statement.py": 17,
     "aliases_typealiastype.py": 24,
     "aliases_variance.py": 3,

diff --git a/pyre2/pyre2/bin/alt/bindings.rs b/pyre2/pyre2/bin/alt/bindings.rs
@@ -1154,15 +1154,22 @@ impl<'a> BindingsBuilder<'a> {
                     let ann_val = if let Some(special) = SpecialForm::new(&name.id, &x.annotation) {
                         BindingAnnotation::Type(special.to_type())
                     } else {
-                        BindingAnnotation::AnnotateExpr(*x.annotation, None)
+                        BindingAnnotation::AnnotateExpr(*x.annotation.clone(), None)
                     };
                     let ann_key = self.table.insert(ann_key, ann_val);
 
-                    if let Some(value) = x.value
+                    if let Some(mut value) = x.value
                         && (!self.module_info.is_interface()
                             || !matches!(&*value, Expr::EllipsisLiteral(_)))
                     {
-                        self.ensure_expr(&value);
+                        // Handle forward references in explicit type aliases.
+                        if let Expr::Name(name) = *x.annotation
+                            && name.id == "TypeAlias"
+                        {
+                            self.ensure_type(&mut value, &mut BindingsBuilder::forward_lookup);
+                        } else {
+                            self.ensure_expr(&value);
+                        }
                         let range = value.range();
                         self.bind_definition(
                             &name.clone(),
@@ -1220,14 +1227,14 @@ impl<'a> BindingsBuilder<'a> {
                 }
                 _ => self.todo("Bindings::stmt AnnAssign", &x),
             },
-            Stmt::TypeAlias(x) => {
+            Stmt::TypeAlias(mut x) => {
                 if let Expr::Name(name) = *x.name {
                     let qs = if let Some(params) = x.type_params {
                         self.type_params(&params)
                     } else {
                         Vec::new()
                     };
-                    self.ensure_expr(&x.value);
+                    self.ensure_type(&mut x.value, &mut BindingsBuilder::forward_lookup);
                     let expr_binding = Binding::Expr(None, *x.value);
                     let binding = Binding::ScopedTypeAlias(
                         name.id.clone(),

diff --git a/pyre2/pyre2/bin/test/type_alias.rs b/pyre2/pyre2/bin/test/type_alias.rs
@@ -129,3 +129,24 @@ X2.__add__  # ok
 X3.__add__  # E: Cannot use type alias `X3`
     "#,
 );
+
+simple_test!(
+    test_forward_ref,
+    r#"
+from typing import TypeAlias, assert_type
+
+X1 = "A"  # Just a normal alias to a str
+X2: TypeAlias = "A"  # Forward ref
+type X3 = "A"  # Forward ref
+
+class A:
+    pass
+
+def f(x1: X1):  # E: untype, got Literal['A']
+    pass
+
+def g(x2: X2, x3: X3):
+    assert_type(x2, A)
+    assert_type(x3, A)
+    "#,
+);