dont use memcpy

Signed-off-by: Shikhar <[email protected]>

Author: shikharish

include/fast_float/ascii_number.h

@@ -528,13 +528,29 @@ parse_int_string(UC const *p, UC const *pend, T &value,
       uint32_t as_int;
     } digits;
 
-    memcpy(&digits.as_int, p, 4);
+    if (cpp20_and_in_constexpr()) {
+      digits.as_int = 0;
+      for (size_t j = 0; j < 4 && j < len; ++j) {
+        digits.as_str[j] = static_cast<uint8_t>(p[j]);
+      }
+    } else {
+      uint32_t b0 = static_cast<uint8_t>(p[0]);
+      uint32_t b1 = (len > 1) ? static_cast<uint8_t>(p[1]) : 0xFFu;
+      uint32_t b2 = (len > 2) ? static_cast<uint8_t>(p[2]) : 0xFFu;
+      uint32_t b3 = (len > 3) ? static_cast<uint8_t>(p[3]) : 0xFFu;
+#if FASTFLOAT_IS_BIG_ENDIAN
+      digits.as_int = (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;
+#else
+      digits.as_int = b0 | (b1 << 8) | (b2 << 16) | (b3 << 24);
+#endif
+    }
+
     uint32_t magic =
         ((digits.as_int + 0x46464646u) | (digits.as_int - 0x30303030u)) &
         0x80808080u;
     uint32_t tz = (uint32_t)std::__countr_zero(magic); // 7, 15, 23, 31, or 32
     uint32_t nd = (tz == 32) ? 4 : (tz >> 3);
-    nd = std::min((size_t)nd, len);
+    nd = (uint32_t)std::min((size_t)nd, len);
     if (nd == 0) {
       if (has_leading_zeros) {
         value = 0;
@@ -548,7 +564,7 @@ parse_int_string(UC const *p, UC const *pend, T &value,
     }
     if (nd > 3) {
       const UC *q = p + nd;
-      uint32_t rem = len - nd;
+      size_t rem = len - nd;
       while (rem) {
         if (*q < UC('0') || *q > UC('9'))
           break;