From f6842f2a4211e3a4977adea49d3d23a4367b67b6 Mon Sep 17 00:00:00 2001
From: jason7708 <jason7708@gmail.com>
Date: Tue, 24 Sep 2024 23:48:44 +0800
Subject: [PATCH] [mph] fix mph::to undefined behavior

---
 mph | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/mph b/mph
index 330d07c..2c4adb0 100644
--- a/mph
+++ b/mph
@@ -774,20 +774,21 @@ template<class T>
         }();
       }
       #endif
-      T t;
-      #pragma GCC diagnostic push
-      #pragma GCC diagnostic ignored "-Warray-bounds"
-      __builtin_memcpy(&t, data.data(), sizeof(t));
-      #pragma GCC diagnostic pop
+      T t{};
+      __builtin_memcpy(&t, data.data(), data.size() < sizeof(t) ? data.size() : sizeof(t));
       const auto index = T(data.size() * __CHAR_BIT__);
       #ifdef __BMI2__
       if constexpr (sizeof(t) <= sizeof(u32)) {
         return __builtin_ia32_bzhi_si(t, index);
       } else if constexpr (sizeof(t) <= sizeof(u64)) {
         return __builtin_ia32_bzhi_di(t, index);
-      } else
+      } else {
+      #endif
+        constexpr T size = sizeof(T) * __CHAR_BIT__;
+        return index >= size ? t : t & ((T(1) << index) - T(1));
+      #ifdef __BMI2__
+      }
       #endif
-        return t & ((T(1) << index) - T(1));
     }
   } else { // unsafe
     #pragma GCC diagnostic push