From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Tyler Veness <calcmogul@gmail.com>
Date: Tue, 28 Jan 2025 22:19:31 -0800
Subject: [PATCH 04/10] Replace std::to_underlying()

---
 include/sleipnir/optimization/problem.hpp   |  9 +++++----
 include/sleipnir/util/print_diagnostics.hpp |  3 ++-
 include/sleipnir/util/to_underlying.hpp     | 14 ++++++++++++++
 3 files changed, 21 insertions(+), 5 deletions(-)
 create mode 100644 include/sleipnir/util/to_underlying.hpp

diff --git a/include/sleipnir/optimization/problem.hpp b/include/sleipnir/optimization/problem.hpp
index 3de6d5bf89a65fe07784350c3b1a4691dfc0c822..273363db2cf75c84d81f2fef36dcb2094303ee2e 100644
--- a/include/sleipnir/optimization/problem.hpp
+++ b/include/sleipnir/optimization/problem.hpp
@@ -37,6 +37,7 @@
 #include "sleipnir/util/profiler.hpp"
 #include "sleipnir/util/spy.hpp"
 #include "sleipnir/util/symbol_exports.hpp"
+#include "sleipnir/util/to_underlying.hpp"
 
 namespace slp {
 
@@ -752,11 +753,11 @@ class Problem {
     // Print problem structure
     slp::println("\nProblem structure:");
     slp::println("  ↳ {} cost function",
-                 types[std::to_underlying(cost_function_type())]);
+                 types[slp::to_underlying(cost_function_type())]);
     slp::println("  ↳ {} equality constraints",
-                 types[std::to_underlying(equality_constraint_type())]);
+                 types[slp::to_underlying(equality_constraint_type())]);
     slp::println("  ↳ {} inequality constraints",
-                 types[std::to_underlying(inequality_constraint_type())]);
+                 types[slp::to_underlying(inequality_constraint_type())]);
 
     if (m_decision_variables.size() == 1) {
       slp::print("\n1 decision variable\n");
@@ -768,7 +769,7 @@ class Problem {
         [](const gch::small_vector<Variable<Scalar>>& constraints) {
           std::array<size_t, 5> counts{};
           for (const auto& constraint : constraints) {
-            ++counts[std::to_underlying(constraint.type())];
+            ++counts[slp::to_underlying(constraint.type())];
           }
           for (const auto& [count, name] :
                std::views::zip(counts, std::array{"empty", "constant", "linear",
diff --git a/include/sleipnir/util/print_diagnostics.hpp b/include/sleipnir/util/print_diagnostics.hpp
index e16ef1b03e675b7ccb8db6781568eec7a44aace7..69cb99957cc7da5abc4162c53a229f7f642bbe4b 100644
--- a/include/sleipnir/util/print_diagnostics.hpp
+++ b/include/sleipnir/util/print_diagnostics.hpp
@@ -17,6 +17,7 @@
 
 #include "sleipnir/util/print.hpp"
 #include "sleipnir/util/profiler.hpp"
+#include "sleipnir/util/to_underlying.hpp"
 
 namespace slp {
 
@@ -239,7 +240,7 @@ void print_iteration_diagnostics(int iterations, IterationType type,
   slp::println(
       "│{:4} {:4} {:9.3f} {:12e} {:13e} {:12e} {:12e} {:.2e} {:<5} {:.2e} "
       "{:.2e} {:2d}│",
-      iterations, ITERATION_TYPES[std::to_underlying(type)], to_ms(time), error,
+      iterations, ITERATION_TYPES[slp::to_underlying(type)], to_ms(time), error,
       cost, infeasibility, complementarity, μ, power_of_10(δ), primal_α, dual_α,
       backtracks);
 }
diff --git a/include/sleipnir/util/to_underlying.hpp b/include/sleipnir/util/to_underlying.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..3f9b4835b912c5a0d998c43828f255c61d0f573e
--- /dev/null
+++ b/include/sleipnir/util/to_underlying.hpp
@@ -0,0 +1,14 @@
+// Copyright (c) Sleipnir contributors
+
+#pragma once
+
+#include <type_traits>
+
+namespace slp {
+
+template <typename Enum>
+constexpr std::underlying_type_t<Enum> to_underlying(Enum e) noexcept {
+  return static_cast<std::underlying_type_t<Enum>>(e);
+}
+
+}  // namespace slp