Fix undefined behavior

no functional change
official-stockfish · Jan 20, 2025 · 703a9b3 · 703a9b3
1 parent 8e3e22b
commit 703a9b3
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Showing 2 changed files with 8 additions and 10 deletions.
diff --git a/src/bitboard.h b/src/bitboard.h
@@ -22,6 +22,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cmath>
+#include <cstring>
 #include <cstdint>
 #include <cstdlib>
 #include <string>
@@ -268,11 +269,11 @@ inline int popcount(Bitboard b) {
 
 #ifndef USE_POPCNT
 
-    union {
-        Bitboard bb;
-        uint16_t u[4];
-    } v = {b};
-    return PopCnt16[v.u[0]] + PopCnt16[v.u[1]] + PopCnt16[v.u[2]] + PopCnt16[v.u[3]];
+    std::uint16_t indices[4];
+    std::memcpy(indices, &b, sizeof(b));
+    return PopCnt16[indices[0]] + PopCnt16[indices[1]] + PopCnt16[indices[2]]
+         + PopCnt16[indices[3]];
+
 
 #elif defined(_MSC_VER)
 

diff --git a/src/misc.h b/src/misc.h
@@ -120,11 +120,8 @@ void sync_cout_start();
 void sync_cout_end();
 
 // True if and only if the binary is compiled on a little-endian machine
-static inline const union {
-    uint32_t i;
-    char     c[4];
-} Le                                    = {0x01020304};
-static inline const bool IsLittleEndian = (Le.c[0] == 4);
+static inline const std::uint16_t Le             = 1;
+static inline const bool          IsLittleEndian = *reinterpret_cast<const char*>(&Le) == 1;
 
 
 template<typename T, std::size_t MaxSize>