feat: Temporal.PlainYearMonth with/toPlainDate——字段 bag 覆盖（month→monthCode→year）、monthCode 两段校验与 day 级日期合成

crates/oxide_builtins/src/temporal.rs

@@ -8837,6 +8837,148 @@ pub fn plain_year_month_subtract<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeRe
     plain_year_month_apply_duration(vm, args, -1)
 }
 
+/// `Temporal.PlainYearMonth.prototype.with(yearMonthLike[, options])`：覆盖 year/month/monthCode；
+/// undefined 不覆盖；calendar/timeZone 键拒绝；无识别字段 → TypeError。
+///
+/// # 步骤
+/// 1. receiver branding（TypeError）。
+/// 2. reject calendar/timeZone 键与 Temporal 实例（TypeError）。
+/// 3. Get 序 month → monthCode → year（字典序）；全 undefined → TypeError。
+/// 4. monthCode 第一段语法校验与字段数值转换先于 options 读取。
+/// 5. 读 overflow（缺省 constrain）；monthCode 第二段适配（闰月后缀/1..12）与
+///    month/monthCode 冲突、>12 钳制在此。
+/// 6. 缺省分量取 receiver 槽（年 0 / 月 1）；(年, 月) 过 ISOYearMonthWithinLimits。
+///
+/// # 边界与副作用
+/// - 结果参考日恒 1，日历标识取自 receiver 槽 3。
+/// - 年月级范围检查（非按日 1），-271821-04 可经 with 产出。
+pub fn plain_year_month_with<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
+    let ptr = native_try!(receiver_obj(vm, args));
+    let obj = unsafe { &*ptr };
+    native_try!(ensure_plain_year_month(vm, obj));
+    let like = if args.len() > 1 { vm.reg(args[1]) } else { JsValue::undefined() };
+    native_try!(reject_partial_object_with_calendar_or_time_zone(vm, like));
+    let lptr = like.as_js_object_ptr();
+    if lptr.is_null() {
+        return NativeResult::Err(crate::error::create_type_error(vm, "invalid argument"));
+    }
+    let like_obj = unsafe { &*lptr };
+    // Get 序（字典序）：month → monthCode → year；无识别字段 → TypeError。
+    let month_raw = native_try!(temporal_option_value(vm, like_obj, like, "month"));
+    let month_code_raw = native_try!(temporal_option_value(vm, like_obj, like, "monthCode"));
+    let month_code = match month_code_raw.is_undefined() {
+        true => None,
+        false => Some(native_try!(temporal_option_string(vm, month_code_raw))),
+    };
+    let year_raw = native_try!(temporal_option_value(vm, like_obj, like, "year"));
+    if [month_raw, month_code_raw, year_raw].iter().all(|raw| raw.is_undefined()) {
+        return NativeResult::Err(crate::error::create_type_error(vm, "no properties present"));
+    }
+    // monthCode 第一段语法（"M"+两位数字，可选再 +"L"）先于一切数值转换。
+    let (month_code_num, leap_month) = match &month_code {
+        Some(text) => {
+            let b = text.as_bytes();
+            let well_formed = b[0] == b'M'
+                && b.len() >= 3
+                && b[1].is_ascii_digit()
+                && b[2].is_ascii_digit()
+                && (b.len() == 3 || (b.len() == 4 && b[3] == b'L'));
+            if !well_formed {
+                return NativeResult::Err(crate::error::create_range_error(vm, "invalid monthCode"));
+            }
+            (Some(u32::from(b[1] - b'0') * 10 + u32::from(b[2] - b'0')), b.len() == 4)
+        }
+        None => (None, false),
+    };
+    // 部分字段先于 options 完整转换（RangeError/TypeError 先于 options 形态错误）。
+    let year = match year_raw.is_undefined() {
+        true => None,
+        false => Some(native_try!(temporal_number_component(vm, year_raw)) as i32),
+    };
+    let month_f = match month_raw.is_undefined() {
+        true => None,
+        false => Some(native_try!(temporal_number_component(vm, month_raw))),
+    };
+    if let Some(f) = month_f {
+        if f < 1.0 {
+            return NativeResult::Err(crate::error::create_range_error(vm, "invalid month"));
+        }
+    }
+    let constrain = native_try!(temporal_overflow(vm, args));
+    if let Some(code) = month_code_num {
+        if leap_month || !(1..=12).contains(&code) {
+            return NativeResult::Err(crate::error::create_range_error(vm, "invalid monthCode"));
+        }
+    }
+    // 月定值：monthCode 与数值 month 并存须一致（冲突 → RangeError）；
+    // 数值 month >12 时 constrain 钳 12、reject 抛错；缺省取 receiver 月（槽 1）。
+    let month = if let Some(code) = month_code_num {
+        if let Some(f) = month_f {
+            if f as u32 != code {
+                return NativeResult::Err(crate::error::create_range_error(vm, "month and monthCode conflict"));
+            }
+        }
+        code
+    } else {
+        match month_f {
+            Some(f) => {
+                if f > 12.0 {
+                    if constrain {
+                        12
+                    } else {
+                        return NativeResult::Err(crate::error::create_range_error(vm, "invalid month"));
+                    }
+                } else {
+                    f as u32
+                }
+            }
+            None => get_double_prop(obj, 1) as u32,
+        }
+    };
+    let year = year.unwrap_or_else(|| get_double_prop(obj, 0) as i32);
+    // (年, 月) 可表示范围（年月级，非按日 1）。
+    if !iso_year_month_within_limits(year, month) {
+        return NativeResult::Err(crate::error::create_range_error(vm, "ISO year-month is out of range"));
+    }
+    let calendar = get_calendar_id(obj, 3);
+    make_plain_year_month(vm, year, month, 1, &calendar)
+}
+
+/// `Temporal.PlainYearMonth.prototype.toPlainDate(dayLike)`：dayLike 须为对象，
+/// 只 Get `day`（year/month/monthCode/calendar 从不读取）；options.overflow 绝不读取；
+/// 合并 (年, 月, 日) 后 constrain 钳 day 至 [1, 月长]，day 级可表示范围检查后
+/// 产出 PlainDate（receiver 日历）。
+pub fn plain_year_month_to_plain_date<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
+    let ptr = native_try!(receiver_obj(vm, args));
+    let obj = unsafe { &*ptr };
+    native_try!(ensure_plain_year_month(vm, obj));
+    let item = if args.len() > 1 { vm.reg(args[1]) } else { JsValue::undefined() };
+    if !item.is_object() {
+        return NativeResult::Err(crate::error::create_type_error(vm, "invalid argument"));
+    }
+    let iptr = item.as_js_object_ptr();
+    if iptr.is_null() {
+        return NativeResult::Err(crate::error::create_type_error(vm, "invalid argument"));
+    }
+    let item_obj = unsafe { &*iptr };
+    let day_raw = native_try!(temporal_option_value(vm, item_obj, item, "day"));
+    if day_raw.is_undefined() {
+        return NativeResult::Err(crate::error::create_type_error(vm, "day is required"));
+    }
+    let day = native_try!(temporal_number_component(vm, day_raw));
+    let year = get_double_prop(obj, 0) as i32;
+    let month = get_double_prop(obj, 1) as u32;
+    // constrain：day 钳到 [1, 月长]。
+    let day = (day as i32).clamp(1, days_in_month_iso(year, month) as i32) as u32;
+    // day 级表示范围：-100_000_001..=100_000_000（年月级合法而 day 级越界在此抛）。
+    let day_count = days_from_civil(i128::from(year), i128::from(month), i128::from(day));
+    if !(-100_000_001..=100_000_000).contains(&day_count) {
+        return NativeResult::Err(crate::error::create_range_error(vm, "date is out of range"));
+    }
+    let calendar = get_calendar_id(obj, 3);
+    make_plain_date(vm, year, month, day, &calendar)
+}
+
 /// `Temporal.PlainMonthDay.prototype.equals(other)`：比较 (月, 日, 参考年) 三元与日历标识；
 /// other 经 ToTemporalMonthDay（串 / 字段对象 / 实例）转换。
 pub fn plain_month_day_equals<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {

crates/oxide_vm/src/bindings/bind_temporal.rs

@@ -1149,6 +1149,12 @@ pub fn bind_temporal(core: &Arc<KernelCore>, session: &KernelSession, global: &m
                 oxide_builtins::temporal::plain_year_month_subtract::<crate::vm::Vm> as *const (),
                 1,
             ),
+            ("with", oxide_builtins::temporal::plain_year_month_with::<crate::vm::Vm> as *const (), 1),
+            (
+                "toPlainDate",
+                oxide_builtins::temporal::plain_year_month_to_plain_date::<crate::vm::Vm> as *const (),
+                1,
+            ),
         ],
     );
     bind_well_known_data_property(

crates/oxide_vm/tests/builtins_temporal_tests.rs

@@ -3406,3 +3406,86 @@ fn plain_year_month_subtract_matrix() {
         "1994-11|2000-02|2018-09|+275760-08|+275759-09|-271821-05|RangeError|RangeError|RangeError|TypeError|RangeError|RangeError|TypeError|RangeError"
     );
 }
+
+#[test]
+fn plain_year_month_with_matrix() {
+    let mut vm = Vm::new();
+    // with：calendar/timeZone 键与实例拒绝；Get 序 month→monthCode→year；
+    // 字段转换先于 options；monthCode 两段校验；constrain 钳 month>12；
+    // 结果参考日恒 1；年月级范围检查。
+    let r = eval(
+        &mut vm,
+        "(() => {
+           const kind = (fn) => { try { fn(); return 'no'; } catch (e) { return e.constructor.name; } };
+           const ym = (s) => Temporal.PlainYearMonth.from(s);
+           return [
+             ym('2019-10').with({ year: 2020 }).toString(),
+             ym('2019-10').with({ month: 9 }).toString(),
+             ym('2019-10').with({ monthCode: 'M09' }).toString(),
+             kind(() => ym('2019-10').with({ month: 9, monthCode: 'M10' })),
+             ym('2019-10').with({ month: 1, years: 2020 }).toString(),
+             ym('2019-10').with({ month: 11, year: undefined }).toString(),
+             ym('2019-10').with({ month: 1.7 }).toString(),
+             ym('2000-05').with({ month: 13 }).month,
+             ym('2000-05').with({ month: 15 }, { overflow: undefined }).month,
+             kind(() => ym('2000-05').with({ month: 15 }, { overflow: 'reject' })),
+             kind(() => ym('2000-05').with({ month: 8 }, { overflow: 'CONSTRAIN' })),
+             kind(() => ym('2000-05').with({ month: 8 }, { overflow: 'balance' })),
+             kind(() => ym('2019-10').with({ month: -1 }, null)),
+             kind(() => ym('2019-10').with({ year: 2020 }, null)),
+             kind(() => ym('2019-10').with({})),
+             kind(() => ym('2019-10').with({ months: 12 })),
+             kind(() => ym('2019-10').with({ year: 2021, calendar: 'iso8601' })),
+             kind(() => ym('2019-10').with({ year: 2021, timeZone: 'UTC' })),
+             kind(() => ym('2019-10').with(42)),
+             kind(() => ym('2019-10').with(new Temporal.PlainDate(2019, 5, 17))),
+             kind(() => ym('2019-10').with({ month: Infinity })),
+             kind(() => ym('2019-10').with({ monthCode: 'M08L' })),
+             kind(() => ym('2019-10').with({ monthCode: 'M13' })),
+             new Temporal.PlainYearMonth(2019, 10, 'iso8601', 5).with({ month: 3 }).toString({ calendarName: 'always' }),
+             ym('2019-10').with({ year: 2020 }, () => {}).toString(),
+             ym('-271821-05').with({ month: 4 }).toString(),
+           ].join('|');
+         })()",
+    )
+    .unwrap();
+    assert_eq!(
+        str_val(&vm, r),
+        "2020-10|2019-09|2019-09|RangeError|2019-01|2019-11|2019-01|12|12|RangeError|RangeError|RangeError|RangeError|TypeError|TypeError|TypeError|TypeError|TypeError|TypeError|TypeError|RangeError|RangeError|RangeError|2019-03-01[u-ca=iso8601]|2020-10|-271821-04"
+    );
+}
+
+#[test]
+fn plain_year_month_to_plain_date_matrix() {
+    let mut vm = Vm::new();
+    // toPlainDate：item 须对象且只读 day；options.overflow 绝不读取；
+    // constrain 钳 day 至 [1, 月长]；day 级范围检查（年月级合法仍可抛）。
+    let r = eval(
+        &mut vm,
+        "(() => {
+           const kind = (fn) => { try { fn(); return 'no'; } catch (e) { return e.constructor.name; } };
+           const ym = (s) => Temporal.PlainYearMonth.from(s);
+           return [
+             ym('2002-01').toPlainDate({ day: 22 }).toString(),
+             kind(() => ym('2002-01').toPlainDate({ something: 'nothing' })),
+             kind(() => ym('2002-01').toPlainDate(7)),
+             kind(() => ym('2002-01').toPlainDate(null)),
+             kind(() => ym('2002-01').toPlainDate({})),
+             ym('2023-02').toPlainDate({ day: 29 }).toString(),
+             ym('1998-06').toPlainDate({ day: 31 }).toString(),
+             ym('2000-05').toPlainDate({ day: 1.9 }).toString(),
+             ym('2000-05').toPlainDate({ day: 0 }).toString(),
+             ym('-271821-04').toPlainDate({ day: 19 }).toString(),
+             kind(() => ym('-271821-04').toPlainDate({ day: 18 })),
+             ym('+275760-09').toPlainDate({ day: 13 }).toString(),
+             kind(() => ym('+275760-09').toPlainDate({ day: 14 })),
+             kind(() => ym('2000-05').toPlainDate({ day: Infinity })),
+           ].join('|');
+         })()",
+    )
+    .unwrap();
+    assert_eq!(
+        str_val(&vm, r),
+        "2002-01-22|TypeError|TypeError|TypeError|TypeError|2023-02-28|1998-06-30|2000-05-01|2000-05-01|-271821-04-19|RangeError|275760-09-13|RangeError|RangeError"
+    );
+}