Provide DynamicAutoDiffCostFunction deduction guide

The deduction guide allows to avoid repeating the CostFunctor type.

Change-Id: I2285de37071006a97f89988baa9b7054d82dae86

include/ceres/dynamic_autodiff_cost_function.h

diff --git a/include/ceres/dynamic_autodiff_cost_function.h b/include/ceres/dynamic_autodiff_cost_function.h
index c21d051..ce0f802 100644
--- a/include/ceres/dynamic_autodiff_cost_function.h
+++ b/include/ceres/dynamic_autodiff_cost_function.h
@@ -1,5 +1,5 @@
 // Ceres Solver - A fast non-linear least squares minimizer
-// Copyright 2019 Google Inc. All rights reserved.
+// Copyright 2023 Google Inc. All rights reserved.
 // http://ceres-solver.org/
 //
 // Redistribution and use in source and binary forms, with or without
@@ -269,6 +269,16 @@
   Ownership ownership_;
 };
 
+// Deduction guide that allows the user to avoid explicitly specifying the
+// template parameter of DynamicAutoDiffCostFunction. The class can instead be
+// instantiated as follows:
+//
+//   new DynamicAutoDiffCostFunction{new MyCostFunctor{}};
+//
+template <typename CostFunctor>
+DynamicAutoDiffCostFunction(CostFunctor* functor, Ownership ownership)
+    -> DynamicAutoDiffCostFunction<CostFunctor>;
+
 }  // namespace ceres
 
 #endif  // CERES_PUBLIC_DYNAMIC_AUTODIFF_COST_FUNCTION_H_

internal/ceres/dynamic_autodiff_cost_function_test.cc

diff --git a/internal/ceres/dynamic_autodiff_cost_function_test.cc b/internal/ceres/dynamic_autodiff_cost_function_test.cc
index 7b2239c..1cf83a5 100644
--- a/internal/ceres/dynamic_autodiff_cost_function_test.cc
+++ b/internal/ceres/dynamic_autodiff_cost_function_test.cc
@@ -1,5 +1,5 @@
 // Ceres Solver - A fast non-linear least squares minimizer
-// Copyright 2022 Google Inc. All rights reserved.
+// Copyright 2023 Google Inc. All rights reserved.
 // http://ceres-solver.org/
 //
 // Redistribution and use in source and binary forms, with or without
@@ -803,4 +803,9 @@
   EXPECT_EQ(residual, target_value);
 }
 
+TEST(DynamicAutoDiffCostFunctionTest, DeductionTemplateCompilationTest) {
+  // Ensure deduction guide to be working
+  (void)DynamicAutoDiffCostFunction(new MyCostFunctor());
+}
+
 }  // namespace ceres::internal