Fixed bug that results in a false positive error under certain circum…

…stances involving a call to a higher-order generic function with another function that involves a class with a contravariant type variable. This addresses #7212.
microsoft · May 31, 2024 · e69974c · e69974c
1 parent 0e42a7e
commit e69974c
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Showing 3 changed files with 38 additions and 3 deletions.
diff --git a/packages/pyright-internal/src/analyzer/typeEvaluator.ts b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
@@ -23480,7 +23480,10 @@ export function createTypeEvaluator(
                 // rather than dest. If the type variable is not in the scope of the
                 // provided TypeVarContext, simply verify that the concrete types are
                 // compatible.
-                if (!srcTypeVarContext || !srcTypeVarContext.hasSolveForScope(getTypeVarScopeId(srcType))) {
+                if (
+                    (flags & AssignTypeFlags.IgnoreTypeVarScope) === 0 &&
+                    (!srcTypeVarContext || !srcTypeVarContext.hasSolveForScope(getTypeVarScopeId(srcType)))
+                ) {
                     return assignType(
                         makeTopLevelTypeVarsConcrete(destType),
                         makeTopLevelTypeVarsConcrete(srcType),
@@ -23497,7 +23500,7 @@ export function createTypeEvaluator(
                             srcType,
                             destType,
                             diag,
-                            srcTypeVarContext,
+                            srcTypeVarContext ?? new TypeVarContext(),
                             originalFlags,
                             recursionCount
                         )
@@ -23515,7 +23518,7 @@ export function createTypeEvaluator(
                                     srcType as TypeVarType,
                                     destSubtype,
                                     diag,
-                                    srcTypeVarContext,
+                                    srcTypeVarContext ?? new TypeVarContext(),
                                     originalFlags,
                                     recursionCount
                                 )

diff --git a/packages/pyright-internal/src/tests/samples/solverHigherOrder12.py b/packages/pyright-internal/src/tests/samples/solverHigherOrder12.py
@@ -0,0 +1,26 @@
+# This sample tests the case involving a higher-order function and a
+# class that uses a contravariant type variable.
+
+from collections.abc import Callable
+from typing import TypeVar, Generic
+
+T = TypeVar("T", contravariant=True)
+A = TypeVar("A")
+B = TypeVar("B")
+C = TypeVar("C")
+
+
+class ClassA(Generic[T]):
+    pass
+
+
+def func1(c: Callable[[A], None], v: A):
+    pass
+
+
+def func2(c: ClassA[B]) -> None:
+    pass
+
+
+def func3(c: ClassA[int]):
+    func1(func2, c)
diff --git a/packages/pyright-internal/src/tests/typeEvaluator2.test.ts b/packages/pyright-internal/src/tests/typeEvaluator2.test.ts
@@ -855,6 +855,12 @@ test('SolverHigherOrder11', () => {
     TestUtils.validateResults(analysisResults, 0);
 });
 
+test('SolverHigherOrder12', () => {
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['solverHigherOrder12.py']);
+
+    TestUtils.validateResults(analysisResults, 0);
+});
+
 test('SolverLiteral1', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['solverLiteral1.py']);