Fixed a false positive error when solving type variables in a call th…

…at involves a lambda. This addresses #8714. (#8730)

packages/pyright-internal/src/analyzer/constraintSolver.ts

@@ -530,10 +530,6 @@ function getTypeVarType(
         }
     }
 
-    if (useLowerBoundOnly) {
-        return entry.lowerBound;
-    }
-
     let result: Type | undefined;
 
     let lowerBound = entry.lowerBound;
@@ -558,7 +554,7 @@ function getTypeVarType(
         }
 
         result = lowerBound;
-    } else {
+    } else if (!useLowerBoundOnly) {
         result = entry.upperBound;
     }
 

packages/pyright-internal/src/analyzer/typeEvaluator.ts

@@ -11500,7 +11500,7 @@ export function createTypeEvaluator(
 
                         // If we skipped a bare type var during the first pass, add
                         // another pass to ensure that we handle all of the type variables.
-                        if (i === 0 && argResult.skippedBareTypeVarExpectedType) {
+                        if (i === 0 && passCount < 2 && argResult.skippedBareTypeVarExpectedType) {
                             passCount++;
                         }
                     });

packages/pyright-internal/src/tests/samples/solver40.py

@@ -0,0 +1,16 @@
+# This sample involves solving type variables that provide a lambda
+# its expected type.
+
+# pyright: strict
+
+from typing import Callable, TypeVar
+
+T = TypeVar("T")
+U = TypeVar("U")
+
+
+def func1(lst: list[T], init: U, f: Callable[[U, T], U]) -> U:
+    ...
+
+
+y = func1([1], 1, lambda x, y: x * y)

packages/pyright-internal/src/tests/typeEvaluator2.test.ts

@@ -807,6 +807,12 @@ test('Solver39', () => {
     TestUtils.validateResults(analysisResults, 0);
 });
 
+test('Solver40', () => {
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['solver40.py']);
+
+    TestUtils.validateResults(analysisResults, 0);
+});
+
 test('SolverScoring1', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['solverScoring1.py']);