[AutoDiff] Fix derivative for array literal with tuple_element_addr elts (swiftlang#78355)

The `adjIndex` was not incremented due to missed `remapType`.

Fixes swiftlang#54214

Author: kovdan01

lib/SILOptimizer/Differentiation/PullbackCloner.cpp

@@ -3284,7 +3284,7 @@ SILValue PullbackCloner::Implementation::getAdjointProjection(
     auto adjSource = getAdjointBuffer(origBB, source);
     if (!adjSource->getType().is<TupleType>())
       return adjSource;
-    auto origTupleTy = source->getType().castTo<TupleType>();
+    auto origTupleTy = remapType(source->getType()).castTo<TupleType>();
     unsigned adjIndex = 0;
     for (unsigned i : range(teai->getFieldIndex())) {
       if (getTangentSpace(

test/AutoDiff/validation-test/array.swift

@@ -192,10 +192,7 @@ ArrayAutoDiffTests.test("ArrayLiteralTuple") {
       return [tuple.0, tuple.1]
     }
     let pb = pullback(at: Float(3), 4, of: { tupleElementGeneric($0, $1) })
-    // FIXME(TF-977): Fix incorrect derivative for array literal with
-    // `tuple_element_addr` elements.
-    // expectEqual((1, 1), pb(FloatArrayTan([1, 1])))
-    expectEqual((0, 2), pb(FloatArrayTan([1, 1])))
+    expectEqual((1, 1), pb(FloatArrayTan([1, 1])))
   }
 }