tree 2ce747d702cf45c399a8dcbe422837c7c017dda0
parent ae3f2e86838d2da241eb00e485a4201b985b9d35
author Sameer Agarwal <sameeragarwal@google.com> 1773783418 -0700
committer Sameer Agarwal <sameeragarwal@google.com> 1773879941 -0700

[modernize] Modernize AutoDiff and NumericDiff CostFunctions to C++17

Modernize the construction and initialization logic of AutoDiffCostFunction,
NumericDiffCostFunction, AutoDiffFirstOrderFunction,
NumericDiffFirstOrderFunction, DynamicAutoDiffCostFunction,
DynamicNumericDiffCostFunction, and CostFunctionToFunctor by utilizing
C++17 features:

- Simplify constructor delegation using if constexpr, removing the need for
  internal InitTag structures.
- Use std::is_constructible_v for cleaner SFINAE in variadic constructors.
- Add static_assert to catch improper usage of DYNAMIC residuals/parameters
  at compile-time.
- Add Ownership support to AutoDiffFirstOrderFunction,
  DynamicAutoDiffCostFunction, and DynamicNumericDiffCostFunction.
- Simplify CostFunctionToFunctor::operator() using variadic parameter packs.
- Use this->num_residuals() for consistent and clear access to base class
  state.
- Minor code quality improvements and removal of redundant template
  parameters.

Change-Id: Id760a26ba2ceca4fb2939ef7632f2f1d9cc430c9