Unconditionally use FindFirstBit in SetBitIterator

Add simple tests

src/core/bitmath_func.hpp

@@ -322,11 +322,7 @@ struct SetBitIterator {
 
 		bool operator==(const Iterator &other) const
 		{
-#ifdef WITH_BITMATH_BUILTINS
 			return this->bitset == other.bitset;
-#else
-			return this->bitset == other.bitset && (this->bitset == 0 || this->bitpos == other.bitpos);
-#endif
 		}
 		bool operator!=(const Iterator &other) const { return !(*this == other); }
 		Tbitpos operator*() const { return this->bitpos; }
@@ -337,29 +333,14 @@ struct SetBitIterator {
 		Tbitpos bitpos;
 		void Validate()
 		{
-#ifdef WITH_BITMATH_BUILTINS
 			if (this->bitset != 0) {
 				typename std::make_unsigned<Tbitset>::type unsigned_value = this->bitset;
-				if (sizeof(Tbitset) <= sizeof(unsigned int)) {
-					bitpos = static_cast<Tbitpos>(__builtin_ctz(unsigned_value));
-				} else if (sizeof(Tbitset) == sizeof(unsigned long)) {
-					bitpos = static_cast<Tbitpos>(__builtin_ctzl(unsigned_value));
-				} else {
-					bitpos = static_cast<Tbitpos>(__builtin_ctzll(unsigned_value));
-				}
+				this->bitpos = static_cast<Tbitpos>(FindFirstBit(unsigned_value));
 			}
-#else
-			while (this->bitset != 0 && (this->bitset & 1) == 0) this->Next();
-#endif
 		}
 		void Next()
 		{
-#ifdef WITH_BITMATH_BUILTINS
-			this->bitset = static_cast<Tbitset>(this->bitset ^ (this->bitset & -this->bitset));
-#else
-			this->bitset = static_cast<Tbitset>(this->bitset >> 1);
-			this->bitpos++;
-#endif
+			this->bitset = KillFirstBit(this->bitset);
 		}
 	};
 

src/tests/bitmath_func.cpp

@@ -51,3 +51,22 @@ TEST_CASE("FindLastBit tests")
 	CHECK(FindLastBit(0x42U) == FindLastBit(0x40U));
 	CHECK(FindLastBit(0xAAAAU) == FindLastBit(0x8000U));
 }
+
+TEST_CASE("SetBitIterator tests")
+{
+	auto test_case = [&](auto input, std::initializer_list<uint> expected) {
+		auto iter = expected.begin();
+		for (auto bit : SetBitIterator(input)) {
+			if (iter == expected.end()) return false;
+			if (bit != *iter) return false;
+			++iter;
+		}
+		return iter == expected.end();
+	};
+	CHECK(test_case(0, {}));
+	CHECK(test_case(1, { 0 }));
+	CHECK(test_case(42, { 1, 3, 5 }));
+	CHECK(test_case(0x8080FFFFU, { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 23, 31 }));
+	CHECK(test_case(INT32_MIN, { 31 }));
+	CHECK(test_case(INT64_MIN, { 63 }));
+}