Better detection of comparability in BoxUtil

gershnik · Jan 9, 2024 · d34aa28 · d34aa28
1 parent a7f81cc
commit d34aa28
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Showing 2 changed files with 34 additions and 3 deletions.
diff --git a/include/objc-helpers/BoxUtil.h b/include/objc-helpers/BoxUtil.h
@@ -111,7 +111,7 @@ template<class T>
 class BoxMaker {
 private:
     static auto detectBoxedType() {
-        if constexpr (std::three_way_comparable<T, std::strong_ordering>) {
+        if constexpr (std::totally_ordered<T>) {
             if constexpr (std::is_copy_constructible_v<T>) {
                 return (NSObject<BoxedValue, BoxedComparable, NSCopying> *)nullptr;
             } else {
@@ -172,7 +172,7 @@ class BoxMaker {
             if (!class_addMethod(cls, objcData.hashSel, IMP(hash), (@encode(NSUInteger) + "@:"s).c_str()))
                 @throw [NSException exceptionWithName:NSGenericException reason:@"class_addMethod(hash) failed" userInfo:nullptr];
 
-            if constexpr (std::three_way_comparable<T, std::strong_ordering>) {
+            if constexpr (std::totally_ordered<T>) {
                 if (!class_addMethod(cls, objcData.compareSel, IMP(compare), (@encode(NSComparisonResult) + "@:@"s).c_str()))
                     @throw [NSException exceptionWithName:NSGenericException reason:@"class_addMethod(compare) failed" userInfo:nullptr];
             }
@@ -274,7 +274,7 @@ class BoxMaker {
             @throw [NSException exceptionWithName:NSInvalidArgumentException reason:@"comparison operand is of invalid type" userInfo:nullptr];
         auto * val = (T *)classData.addrOfValue(self);
         auto * otherVal = (T *)classData.addrOfValue(other);
-        const auto res = *val <=> *otherVal;
+        const auto res = std::compare_strong_order_fallback(*val, *otherVal);
         return NSComparisonResult(-(res < 0) + (res > 0));
     }
 public:

diff --git a/test/BoxUtilTests.mm b/test/BoxUtilTests.mm
@@ -143,6 +143,37 @@
     CHECK([obj.description isEqualToString:@"Boxed object of type \"qwerty\""]);
 }
 
+struct no_spaceship {
+    int i;
+
+    bool operator==(const no_spaceship &) const = default;
+    bool operator!=(const no_spaceship &) const = default;
+    bool operator<(const no_spaceship & rhs) const { return i < rhs.i; }
+    bool operator<=(const no_spaceship & rhs) const { return i <= rhs.i; }
+    bool operator>(const no_spaceship & rhs) const { return i > rhs.i; }
+    bool operator>=(const no_spaceship & rhs) const { return i >= rhs.i; }
+};
+
+TEST_CASE( "no-spaceship" ) {
+    auto obj1 = box(no_spaceship{3});
+    auto obj2 = box(no_spaceship{4});
+    CHECK([obj1 compare:obj2] == NSOrderedAscending);
+}
+
+struct spaceship_only {
+    int i;
+
+    std::strong_ordering operator<=>(const spaceship_only &) const = default;
+};
+
+TEST_CASE( "no-spaceship" ) {
+    auto obj1 = box(spaceship_only{3});
+    auto obj2 = box(spaceship_only{4});
+    CHECK([obj1 compare:obj2] == NSOrderedAscending);
+
+    auto obj3 = box(spaceship_only{3});
+    CHECK([obj3 isEqual:obj1]);
+}
 
 
 TEST_SUITE_END();