From 0edcd2eecfbf2b9703a99f9b12a00a79c30d511f Mon Sep 17 00:00:00 2001
From: Eric Traut <eric@traut.com>
Date: Tue, 11 Jun 2024 09:08:46 -0700
Subject: [PATCH] Fixed bug that results in parameter types being converted to
 `Any` when converting a `NewType` or dataclass constructor to a callable.
 This addresses #8116. (#8117)

---
 .../src/analyzer/constraintSolver.ts                 |  5 +----
 .../pyright-internal/src/analyzer/constructors.ts    |  2 --
 packages/pyright-internal/src/analyzer/protocols.ts  | 12 +++++++++++-
 .../src/tests/samples/constructorCallable1.py        | 12 ++++++++++++
 4 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/packages/pyright-internal/src/analyzer/constraintSolver.ts b/packages/pyright-internal/src/analyzer/constraintSolver.ts
index abf42c83d..e78e5219a 100644
--- a/packages/pyright-internal/src/analyzer/constraintSolver.ts
+++ b/packages/pyright-internal/src/analyzer/constraintSolver.ts
@@ -326,10 +326,7 @@ export function assignTypeToTypeVar(
                 )
             ) {
                 // The srcType is narrower than the current wideTypeBound, so replace it.
-                // If it's Any, don't replace it because Any is the narrowest type already.
-                if (!isAnyOrUnknown(curWideTypeBound)) {
-                    newWideTypeBound = adjSrcType;
-                }
+                newWideTypeBound = adjSrcType;
             } else if (
                 !evaluator.assignType(
                     adjSrcType,
diff --git a/packages/pyright-internal/src/analyzer/constructors.ts b/packages/pyright-internal/src/analyzer/constructors.ts
index 6a724f374..672fba6a2 100644
--- a/packages/pyright-internal/src/analyzer/constructors.ts
+++ b/packages/pyright-internal/src/analyzer/constructors.ts
@@ -1087,8 +1087,6 @@ function createFunctionFromInitMethod(
 
         const convertedInit = FunctionType.clone(boundInit);
         convertedInit.details.declaredReturnType = boundInit.strippedFirstParamType ?? selfType ?? objectType;
-        convertedInit.details.name = '';
-        convertedInit.details.fullName = '';
 
         if (convertedInit.specializedTypes) {
             convertedInit.specializedTypes.returnType = selfType ?? objectType;
diff --git a/packages/pyright-internal/src/analyzer/protocols.ts b/packages/pyright-internal/src/analyzer/protocols.ts
index e2001435b..a52d49090 100644
--- a/packages/pyright-internal/src/analyzer/protocols.ts
+++ b/packages/pyright-internal/src/analyzer/protocols.ts
@@ -32,6 +32,7 @@ import {
     TypeBase,
     TypeVarType,
     UnknownType,
+    Variance,
 } from './types';
 import {
     applySolvedTypeVars,
@@ -778,7 +779,7 @@ function createProtocolTypeVarContext(
             );
         } else if (destType.typeArguments && index < destType.typeArguments.length) {
             let typeArg = destType.typeArguments[index];
-            let flags = AssignTypeFlags.PopulatingExpectedType;
+            let flags: AssignTypeFlags;
             let hasUnsolvedTypeVars = requiresSpecialization(typeArg);
 
             // If the type argument has unsolved TypeVars, see if they have
@@ -787,6 +788,15 @@ function createProtocolTypeVarContext(
                 typeArg = applySolvedTypeVars(typeArg, destTypeVarContext, { useNarrowBoundOnly: true });
                 flags = AssignTypeFlags.Default;
                 hasUnsolvedTypeVars = requiresSpecialization(typeArg);
+            } else {
+                flags = AssignTypeFlags.PopulatingExpectedType;
+
+                const variance = TypeVarType.getVariance(typeParam);
+                if (variance === Variance.Invariant) {
+                    flags |= AssignTypeFlags.EnforceInvariance;
+                } else if (variance === Variance.Contravariant) {
+                    flags |= AssignTypeFlags.ReverseTypeVarMatching;
+                }
             }
 
             if (!hasUnsolvedTypeVars) {
diff --git a/packages/pyright-internal/src/tests/samples/constructorCallable1.py b/packages/pyright-internal/src/tests/samples/constructorCallable1.py
index 078086726..d7917d2e9 100644
--- a/packages/pyright-internal/src/tests/samples/constructorCallable1.py
+++ b/packages/pyright-internal/src/tests/samples/constructorCallable1.py
@@ -135,3 +135,15 @@ def func3(t: type[object]):
     reveal_type(
         cast_to_callable(t), expected_text="(*args: Any, **kwargs: Any) -> object"
     )
+
+
+@dataclass
+class G:
+    value: int
+
+
+def func4(c: Callable[[T1], T2]) -> Callable[[T1], T2]:
+    return c
+
+
+reveal_type(func4(G), expected_text="(int) -> G")