[wpimath] Constexprify units unary operators

Fixes wpilibsuite#4137.
calcmogul · Mar 29, 2022 · 947ed2d · 947ed2d
1 parent 126e3de
commit 947ed2d
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Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/wpimath/src/main/native/include/units/base.h b/wpimath/src/main/native/include/units/base.h
@@ -2328,7 +2328,7 @@ namespace units
 
 	// unary addition: +T
 	template<class Units, typename T, template<typename> class NonLinearScale>
-	inline unit_t<Units, T, NonLinearScale> operator+(const unit_t<Units, T, NonLinearScale>& u) noexcept
+	constexpr inline unit_t<Units, T, NonLinearScale> operator+(const unit_t<Units, T, NonLinearScale>& u) noexcept
 	{
 		return u;
 	}
@@ -2352,7 +2352,7 @@ namespace units
 
 	// unary addition: -T
 	template<class Units, typename T, template<typename> class NonLinearScale>
-	inline unit_t<Units, T, NonLinearScale> operator-(const unit_t<Units, T, NonLinearScale>& u) noexcept
+	constexpr inline unit_t<Units, T, NonLinearScale> operator-(const unit_t<Units, T, NonLinearScale>& u) noexcept
 	{
 		return unit_t<Units, T, NonLinearScale>(-u());
 	}

diff --git a/wpimath/src/test/native/cpp/UnitsTest.cpp b/wpimath/src/test/native/cpp/UnitsTest.cpp
@@ -3063,14 +3063,17 @@ TEST_F(Constexpr, construction) {
   constexpr meter_t result0(0);
   constexpr auto result1 = make_unit<meter_t>(1);
   constexpr auto result2 = meter_t(2);
+  constexpr auto result3 = -3_m;
 
   EXPECT_EQ(meter_t(0), result0);
   EXPECT_EQ(meter_t(1), result1);
   EXPECT_EQ(meter_t(2), result2);
+  EXPECT_EQ(meter_t(-3), result3);
 
   EXPECT_TRUE(noexcept(result0));
   EXPECT_TRUE(noexcept(result1));
   EXPECT_TRUE(noexcept(result2));
+  EXPECT_TRUE(noexcept(result3));
 }
 
 TEST_F(Constexpr, constants) {