Fixed a bug that led to a false positive error when specializing a ty…

…pe alias consisting of a callable parameterized by a TypeVarTuple. This partially addresses microsoft#6317.
StellaHuang95 · Nov 3, 2023 · fb67700 · fb67700
1 parent 841a79e
commit fb67700
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Showing 2 changed files with 11 additions and 2 deletions.
diff --git a/packages/pyright-internal/src/analyzer/typeUtils.ts b/packages/pyright-internal/src/analyzer/typeUtils.ts
@@ -3791,7 +3791,9 @@ class TypeVarTransformer {
             }
 
             // Unpack the tuple and synthesize a new function in the process.
-            const newFunctionType = FunctionType.createSynthesizedInstance('', functionType.details.flags);
+            const newFunctionType = TypeBase.isInstantiable(functionType)
+                ? FunctionType.createInstantiable(functionType.details.flags | FunctionTypeFlags.SynthesizedMethod)
+                : FunctionType.createSynthesizedInstance('', functionType.details.flags);
             let insertKeywordOnlySeparator = false;
             let swallowPositionOnlySeparator = false;
 

diff --git a/packages/pyright-internal/src/tests/samples/variadicTypeVar6.py b/packages/pyright-internal/src/tests/samples/variadicTypeVar6.py
@@ -3,7 +3,7 @@
 
 # pyright: reportMissingModuleSource=false, reportMissingTypeArgument=true
 
-from typing import Generic, TypeVar, Union
+from typing import Callable, Generic, TypeVar, Union
 from typing_extensions import TypeVarTuple, Unpack
 
 _Xs = TypeVarTuple("_Xs")
@@ -76,3 +76,10 @@ def func2(x: Alias6[float, bool], y: Alias6, z: Alias6[()]):
     reveal_type(y, expected_text="tuple[int, Unknown]")
 
     reveal_type(z, expected_text="tuple[int]")
+
+
+Alias7 = Callable[[Unpack[_Xs]], None]
+
+
+def func3(cb: Alias7[int, Unpack[_Xs]]) -> tuple[Unpack[_Xs]]:
+    ...