value: Support converting BigInt to (u)int64 values

BigInt values are now accepted as parameters to C functions that take
64-bit integers.

For now BigInts are only accepted for 64-bit parameters. We may allow
BigInt for any parameter in the future (once we've checked that we don't
go out-of-range), for now we assume that BigInt values are used only for
functions taking a type that can mostly handle them.

For bounds checks, given that we don't have a bigger value holder than
(u)int64_t, we have to create a new wrapper to avoid taking the fast path
in gjs_arg_set_from_js_value(), and without having to hack
type_has_js_getter().

As per this, now for 64bit integers we use TypeWrapper as the type holder
that has conversion operators to the base type, and for which we can then
add a js_value_to_c_checked() specialization.

See: #271

1 files changed, 2 insertions, 15 deletions

diff --git a/gi/arg-inl.h b/gi/arg-inl.h
index 19de766b..5fb19e3b 100644
--- a/gi/arg-inl.h
+++ b/gi/arg-inl.h
@@ -174,19 +174,6 @@ template <typename T, GITypeTag TAG = GI_TYPE_TAG_VOID>
 // Implementation to store rounded (u)int64_t numbers into double
 
 template <typename BigT>
-[[nodiscard]] inline constexpr BigT max_safe_big_number() {
-    return (BigT(1) << std::numeric_limits<double>::digits) - 1;
-}
-
-template <typename BigT>
-[[nodiscard]] inline constexpr BigT min_safe_big_number() {
-    if constexpr (std::is_signed_v<BigT>)
-        return -(max_safe_big_number<BigT>());
-
-    return std::numeric_limits<BigT>::lowest();
-}
-
-template <typename BigT>
 [[nodiscard]] inline std::enable_if_t<std::is_integral_v<BigT> &&
                                           (std::numeric_limits<BigT>::max() >
                                            std::numeric_limits<int32_t>::max()),
@@ -194,8 +181,8 @@ template <typename BigT>
 gjs_arg_get_maybe_rounded(GIArgument* arg) {
     BigT val = gjs_arg_get<BigT>(arg);
 
-    if (val < min_safe_big_number<BigT>() ||
-        val > max_safe_big_number<BigT>()) {
+    if (val < Gjs::min_safe_big_number<BigT>() ||
+        val > Gjs::max_safe_big_number<BigT>()) {
         g_warning(
             "Value %s cannot be safely stored in a JS Number "
             "and may be rounded",