# HG changeset patch
# User Rubidium <rubidium@openttd.org>
# Date 2024-01-18 20:45:42
# Node ID cb7396c4e0bcdcaba8b4fb918aedaf341c0d40b2
# Parent  2d72649168678bccf74334821d7cfa7b2ef0e170

Codechange: use std::popcount instead of hand written loop

diff --git a/src/core/bitmath_func.hpp b/src/core/bitmath_func.hpp
--- a/src/core/bitmath_func.hpp
+++ b/src/core/bitmath_func.hpp
@@ -248,20 +248,13 @@ inline T KillFirstBit(T value)
  * @return the number of bits.
  */
 template <typename T>
-inline uint CountBits(T value)
+constexpr uint CountBits(T value)
 {
-	uint num;
-
-	/* This loop is only called once for every bit set by clearing the lowest
-	 * bit in each loop. The number of bits is therefore equal to the number of
-	 * times the loop was called. It was found at the following website:
-	 * http://graphics.stanford.edu/~seander/bithacks.html */
-
-	for (num = 0; value != 0; num++) {
-		value &= (T)(value - 1);
+	if constexpr (std::is_enum_v<T>) {
+		return std::popcount<std::underlying_type_t<T>>(value);
+	} else {
+		return std::popcount(value);
 	}
-
-	return num;
 }
 
 /**
diff --git a/src/script/api/script_goal.cpp b/src/script/api/script_goal.cpp
--- a/src/script/api/script_goal.cpp
+++ b/src/script/api/script_goal.cpp
@@ -126,7 +126,7 @@
 	std::string text = question->GetEncodedText();
 	EnforcePreconditionEncodedText(false, text);
 	uint min_buttons = (type == QT_QUESTION ? 1 : 0);
-	EnforcePrecondition(false, CountBits(buttons) >= min_buttons && CountBits(buttons) <= 3);
+	EnforcePrecondition(false, CountBits<uint64_t>(buttons) >= min_buttons && CountBits<uint64_t>(buttons) <= 3);
 	EnforcePrecondition(false, buttons >= 0 && buttons < (1 << ::GOAL_QUESTION_BUTTON_COUNT));
 	EnforcePrecondition(false, (int)type < ::GQT_END);
 	EnforcePrecondition(false, uniqueid >= 0 && uniqueid <= UINT16_MAX);