Fixed bug that resulted in incorrect type evaluation when a TypeAlias…

…Type is used in a value expression. This addresses #7109.
microsoft · Jan 28, 2024 · 509bf69 · 509bf69
1 parent 928d1cf
commit 509bf69
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Showing 4 changed files with 21 additions and 5 deletions.
diff --git a/packages/pyright-internal/src/analyzer/typeEvaluator.ts b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
@@ -15302,7 +15302,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
         if (isPep695Syntax || isPep695TypeVarType) {
             const typeAliasTypeClass = getTypingType(errorNode, 'TypeAliasType');
             if (typeAliasTypeClass && isInstantiableClass(typeAliasTypeClass)) {
-                typeAlias = TypeBase.cloneAsSpecialForm(typeAlias, typeAliasTypeClass);
+                typeAlias = TypeBase.cloneAsSpecialForm(typeAlias, ClassType.cloneAsInstance(typeAliasTypeClass));
             }
         }
 

diff --git a/packages/pyright-internal/src/tests/samples/typeAliasStatement1.py b/packages/pyright-internal/src/tests/samples/typeAliasStatement1.py
@@ -8,8 +8,10 @@
 
 type TA1[T1] = int
 
+
 class ClassA[T2]:
-    type TA2 = int; type TA3 = str
+    type TA2 = int
+    type TA3 = str
 
     type TA4 = int
 
@@ -38,6 +40,7 @@ class ClassA[T2]:
 def func1() -> type[int]:
     ...
 
+
 # This should generate an error because a call expression is not
 # allowed in a type alias definition.
 type TA8 = func1()
@@ -57,19 +60,25 @@ def func1() -> type[int]:
 
 list[TA10]()
 
+
 # This should generate an error.
-class DerivedInt(TA10): pass
+class DerivedInt(TA10):
+    pass
+
 
 def func2(x: object):
-    # This should generate an error.
+    # This should generate two errors.
     if isinstance(x, TA10):
         reveal_type(x)
 
+
 type TA11 = Callable[..., Any]
 
+
 def func3(cb: TA11):
     cb()
 
+
 def func4():
     # This should generate an error.
     type TA12 = int
diff --git a/packages/pyright-internal/src/tests/samples/typeAliasType2.py b/packages/pyright-internal/src/tests/samples/typeAliasType2.py
@@ -53,3 +53,10 @@ class A(Generic[T]):
 
 # This should generate an error because S is not in scope.
 TA8 = TypeAliasType("TA8", list[S])
+
+
+def identity[T](t: T) -> T:
+    return t
+
+
+reveal_type(identity(TA1), expected_text="TypeAliasType")
diff --git a/packages/pyright-internal/src/tests/typeEvaluator5.test.ts b/packages/pyright-internal/src/tests/typeEvaluator5.test.ts
@@ -115,7 +115,7 @@ test('TypeAliasStatement1', () => {
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeAliasStatement1.py'], configOptions);
-    TestUtils.validateResults(analysisResults, 8);
+    TestUtils.validateResults(analysisResults, 9);
 });
 
 test('TypeAliasStatement2', () => {