size: gate Date toLocale* + Intl subclass-super behind intl-namespace (hello −99 KB, crosses under 4.1 MB)

changelog.d/7009-intl-tolocale-gate.md

@@ -0,0 +1 @@
+**Binary size:** the `Date.prototype.toLocale{,Date,Time}String` implementation and the `class X extends Intl.<Ctor>` super probe in the fetch-globals construct path now sit behind the existing `intl-namespace` feature. These were the last two always-live references into the Intl formatting web: the Date prototype is installed in every binary, so its locale thunks pinned ~99 KB of Intl machinery even in programs with no locale API. The compiler's `intl-namespace` detection already covers every `toLocale*` token, so any program that can reach these keeps them; with the feature off the Date thunks defer to the non-locale formatter (unreachable in practice) and the Intl subclass probe can never match. Hello world: −99 KB (4,344,464 → 4,245,216 bytes).

crates/perry-runtime/src/object/date_proto_thunks.rs

@@ -500,6 +500,19 @@ date_setter_thunk!(date_set_utc_milliseconds, 1, 6);
 /// both. A `Date` is a specific INSTANT, so we shift its epoch into the resolved
 /// zone's wall clock (the `timeZone` option, else the host zone) before
 /// formatting it as the now-zone-agnostic date-time.
+/// Locale-aware `Date.prototype.toLocale*String`. Behind `intl-namespace`
+/// (which the compiler enables on any `toLocale*` token, among others): with
+/// the feature off no program in this binary can call these thunks, so the
+/// fallback simply defers to the non-locale formatter instead of statically
+/// pinning the Intl formatting web from the always-installed Date prototype.
+#[cfg(not(feature = "intl-namespace"))]
+fn date_to_locale_opts_impl(_rest: f64, _ctx: crate::intl::TemporalLocaleCtx) -> f64 {
+    let this = require_date_this();
+    let s = crate::date::js_date_to_locale_string(this);
+    crate::value::js_nanbox_string(s as i64)
+}
+
+#[cfg(feature = "intl-namespace")]
 fn date_to_locale_opts_impl(rest: f64, ctx: crate::intl::TemporalLocaleCtx) -> f64 {
     let this = require_date_this();
     let epoch_ms = crate::date::date_cell_timestamp(this);

crates/perry-runtime/src/object/global_this/fetch_globals.rs

@@ -589,6 +589,10 @@ pub unsafe extern "C" fn js_fetch_or_value_super(
     // and construct it with `new.target` set, re-homing the instance's brand +
     // methods onto `this`. `parent_val` can arrive stale for an aliased heritage
     // (`const L = Intl.Locale; class X extends L`); recover the decl-time parent.
+    // Behind `intl-namespace`: with the feature off no Intl constructor value
+    // exists, so this probe can never match — and skipping it keeps this
+    // always-live construct path from pinning the Intl web.
+    #[cfg(feature = "intl-namespace")]
     {
         let intl_parent = if crate::intl::is_intl_constructor_value(parent_val) {
             parent_val