In file included from oi-userland/components/web/firefox-nightly/build/amd64/dist/system_wrappers/utility:3,
                 from oi-userland/components/web/firefox-nightly/build/amd64/dist/stl_wrappers/utility:59,
                 from oi-userland/components/web/firefox-nightly/build/amd64/dist/include/mozilla/Maybe.h:14,
                 from oi-userland/components/web/firefox-nightly/firefox-c836d51da4179d7b456d02d22e2f40c8b1a9b3d7/js/src/vm/TaggedProto.h:10,
                 from oi-userland/components/web/firefox-nightly/firefox-c836d51da4179d7b456d02d22e2f40c8b1a9b3d7/js/src/vm/TaggedProto.cpp:7,
                 from Unified_cpp_js_src_vm15.cpp:2:
/usr/gcc/14/include/c++/14.3.0/utility: In instantiation of 'constexpr bool std::in_range(_Tp) [with _Res = char; _Tp = long int]':
oi-userland/components/web/firefox-nightly/build/amd64/dist/include/mozilla/CheckedInt.h:289:53:   required from 'constexpr mozilla::CheckedInt<T>::CheckedInt(U) [with U = long int; T = char]'
  289 |       : mValue(T(aValue)), mIsValid(std::in_range<T>(aValue)) {
      |                                     ~~~~~~~~~~~~~~~~^~~~~~~~
oi-userland/components/web/firefox-nightly/firefox-c836d51da4179d7b456d02d22e2f40c8b1a9b3d7/js/src/vm/TypedArrayObject.cpp:2589:37:   required from 'std::enable_if_t<((bool)(std::numeric_limits<_Tp>::is_integer && (sizeof (NativeType) < 8))), long int> TypedArrayIndexOf(js::TypedArrayObject*, size_t, size_t, const JS::Value&) [with ExternalType = char; NativeType = char; std::enable_if_t<((bool)(std::numeric_limits<_Tp>::is_integer && (sizeof (NativeType) < 8))), long int> = long int; size_t = long unsigned int]'
 2589 |   mozilla::CheckedInt<ExternalType> checked{d};
      |                                     ^~~~~~~
oi-userland/components/web/firefox-nightly/firefox-c836d51da4179d7b456d02d22e2f40c8b1a9b3d7/js/src/vm/TypedArrayObject.cpp:2692:5:   required from here
 2689 |     result = TypedArrayIndexOf<ExternalType, NativeType>(tarray, k, len, \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
 2690 |                                                          args.get(0));   \
      |                                                          ~~~~~~~~~~~~
/usr/gcc/14/include/c++/14.3.0/utility:179:50: error: static assertion failed
  179 |       static_assert(__is_standard_integer<_Res>::value);
      |                                                  ^~~~~
/usr/gcc/14/include/c++/14.3.0/utility:179:50: note: 'std::integral_constant<bool, false>::value' evaluates to false

--- firefox-c836d51da4179d7b456d02d22e2f40c8b1a9b3d7/mfbt/CheckedInt.h.old
+++ firefox-c836d51da4179d7b456d02d22e2f40c8b1a9b3d7/mfbt/CheckedInt.h
@@ -14,7 +14,6 @@
 #include <cstdint>
 #include <limits>
 #include <type_traits>
-#include <utility>
 
 namespace mozilla {
 
@@ -85,6 +84,11 @@
 };
 
 template <>
+struct IsSupportedPass2<char> {
+  static const bool value = true;
+};
+
+template <>
 struct IsSupportedPass2<signed char> {
   static const bool value = true;
 };
@@ -140,6 +144,71 @@
  * Ideas taken from IntegerLib, code different.
  */
 
+template <typename T, typename U, bool IsTSigned = std::is_signed_v<T>,
+          bool IsUSigned = std::is_signed_v<U>>
+struct DoesRangeContainRange {};
+
+template <typename T, typename U, bool Signedness>
+struct DoesRangeContainRange<T, U, Signedness, Signedness> {
+  static const bool value = sizeof(T) >= sizeof(U);
+};
+
+template <typename T, typename U>
+struct DoesRangeContainRange<T, U, true, false> {
+  static const bool value = sizeof(T) > sizeof(U);
+};
+
+template <typename T, typename U>
+struct DoesRangeContainRange<T, U, false, true> {
+  static const bool value = false;
+};
+
+template <typename T, typename U, bool IsTSigned = std::is_signed_v<T>,
+          bool IsUSigned = std::is_signed_v<U>,
+          bool DoesTRangeContainURange = DoesRangeContainRange<T, U>::value>
+struct IsInRangeImpl {};
+
+template <typename T, typename U, bool IsTSigned, bool IsUSigned>
+struct IsInRangeImpl<T, U, IsTSigned, IsUSigned, true> {
+  static constexpr bool run(U) { return true; }
+};
+
+template <typename T, typename U>
+struct IsInRangeImpl<T, U, true, true, false> {
+  static constexpr bool run(U aX) {
+    return aX <= std::numeric_limits<T>::max() &&
+           aX >= std::numeric_limits<T>::min();
+  }
+};
+
+template <typename T, typename U>
+struct IsInRangeImpl<T, U, false, false, false> {
+  static constexpr bool run(U aX) {
+    return aX <= std::numeric_limits<T>::max();
+  }
+};
+
+template <typename T, typename U>
+struct IsInRangeImpl<T, U, true, false, false> {
+  static constexpr bool run(U aX) {
+    return sizeof(T) > sizeof(U) || aX <= U(std::numeric_limits<T>::max());
+  }
+};
+
+template <typename T, typename U>
+struct IsInRangeImpl<T, U, false, true, false> {
+  static constexpr bool run(U aX) {
+    return sizeof(T) >= sizeof(U)
+               ? aX >= 0
+               : aX >= 0 && aX <= U(std::numeric_limits<T>::max());
+  }
+};
+
+template <typename T, typename U>
+constexpr bool IsInRange(U aX) {
+  return IsInRangeImpl<T, U>::run(aX);
+}
+
 template <typename T>
 constexpr bool IsDivValid(T aX, T aY) {
   // Keep in mind that in the signed case, min/-1 is invalid because
@@ -190,7 +259,7 @@
   static constexpr CheckedInt<T> negate(const CheckedInt<T>& aVal) {
     // Handle negation separately for signed/unsigned, for simpler code and to
     // avoid an MSVC warning negating an unsigned value.
-    static_assert(std::in_range<T>(0), "Integer type can't represent 0");
+    static_assert(detail::IsInRange<T>(0), "Integer type can't represent 0");
     return CheckedInt<T>(T(0), aVal.isValid() && aVal.mValue == 0);
   }
 };
@@ -314,7 +383,7 @@
    */
   template <typename U>
   MOZ_IMPLICIT MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT constexpr CheckedInt(U aValue)
-      : mValue(T(aValue)), mIsValid(std::in_range<T>(aValue)) {
+      : mValue(T(aValue)), mIsValid(detail::IsInRange<T>(aValue)) {
     static_assert(
         detail::IsSupported<T>::value && detail::IsSupported<U>::value,
         "This type is not supported by CheckedInt");
@@ -334,7 +403,7 @@
   constexpr CheckedInt() : mValue(T(0)), mIsValid(true) {
     static_assert(detail::IsSupported<T>::value,
                   "This type is not supported by CheckedInt");
-    static_assert(std::in_range<T>(0), "Integer type can't represent 0");
+    static_assert(detail::IsInRange<T>(0), "Integer type can't represent 0");
   }
 
   /** @returns the actual value */
@@ -461,7 +530,8 @@
   constexpr CheckedInt<T> operator OP(const CheckedInt<T>& aLhs,            \
                                       const CheckedInt<T>& aRhs) {          \
     if (!detail::Is##NAME##Valid(aLhs.mValue, aRhs.mValue)) {               \
-      static_assert(std::in_range<T>(0), "Integer type can't represent 0"); \
+      static_assert(detail::IsInRange<T>(0),                                \
+                    "Integer type can't represent 0");                      \
       return CheckedInt<T>(T(0), false);                                    \
     }                                                                       \
     /* For some T, arithmetic ops automatically promote to a wider type, so \
@@ -471,16 +541,17 @@
                          aLhs.mIsValid && aRhs.mIsValid);                   \
   }
 
-#define MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR2(NAME, OP, FUN)                \
-  template <typename T>                                                     \
-  constexpr CheckedInt<T> operator OP(const CheckedInt<T>& aLhs,            \
-                                      const CheckedInt<T>& aRhs) {          \
-    auto result = T{};                                                      \
-    if (MOZ_UNLIKELY(!FUN(aLhs.mValue, aRhs.mValue, &result))) {            \
-      static_assert(std::in_range<T>(0), "Integer type can't represent 0"); \
-      return CheckedInt<T>(T(0), false);                                    \
-    }                                                                       \
-    return CheckedInt<T>(result, aLhs.mIsValid && aRhs.mIsValid);           \
+#define MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR2(NAME, OP, FUN)       \
+  template <typename T>                                            \
+  constexpr CheckedInt<T> operator OP(const CheckedInt<T>& aLhs,   \
+                                      const CheckedInt<T>& aRhs) { \
+    auto result = T{};                                             \
+    if (MOZ_UNLIKELY(!FUN(aLhs.mValue, aRhs.mValue, &result))) {   \
+      static_assert(detail::IsInRange<T>(0),                       \
+                    "Integer type can't represent 0");             \
+      return CheckedInt<T>(T(0), false);                           \
+    }                                                              \
+    return CheckedInt<T>(result, aLhs.mIsValid && aRhs.mIsValid);  \
   }
 MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR2(Add, +, SafeAdd)
 MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR2(Sub, -, SafeSub)