From 871769c815ed068665e94ad4cd403672855e7d4e Mon Sep 17 00:00:00 2001
From: Joseph Eng <91924258+KangarooKoala@users.noreply.github.com>
Date: Thu, 2 Oct 2025 17:36:30 -0700
Subject: [PATCH] [wpimath] Fix units overload resolution (#8267)

---
 wpimath/src/main/native/include/units/base.h |  1 +
 wpimath/src/test/native/cpp/UnitsTest.cpp    | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/wpimath/src/main/native/include/units/base.h b/wpimath/src/main/native/include/units/base.h
index fc5ae4b29d..626d76e16e 100644
--- a/wpimath/src/main/native/include/units/base.h
+++ b/wpimath/src/main/native/include/units/base.h
@@ -1992,6 +1992,7 @@ namespace units
 		 * @param[in]	rhs unit to copy.
 		 */
 		template<class UnitsRhs, typename Ty, template<typename> class NlsRhs>
+			requires traits::is_unit_v<UnitsRhs> && traits::is_unit_v<Units> && traits::is_convertible_unit_v<UnitsRhs, Units>
 		constexpr unit_t(const unit_t<UnitsRhs, Ty, NlsRhs>& rhs) noexcept :
 		nls(units::convert<UnitsRhs, Units, T>(rhs.m_value), std::true_type() /*store linear value*/)
 		{
diff --git a/wpimath/src/test/native/cpp/UnitsTest.cpp b/wpimath/src/test/native/cpp/UnitsTest.cpp
index 6357e79103..3b6cd606e3 100644
--- a/wpimath/src/test/native/cpp/UnitsTest.cpp
+++ b/wpimath/src/test/native/cpp/UnitsTest.cpp
@@ -3513,3 +3513,18 @@ TEST_F(CaseStudies, pythagoreanTheorum) {
                   pow<2>(RightTriangle::b::value()) ==
               pow<2>(RightTriangle::c::value()));
 }
+
+TEST(Units, overloadResolution) {
+  // Slight hack to get nested functions
+  struct Scope {
+    static bool f(units::meter_t) {
+      return true;
+    };
+
+    static bool f(units::second_t) {
+      return false;
+    };
+  };
+  // Make sure this properly selects the meter overload
+  EXPECT_TRUE(Scope::f(1_mm));
+}