fix canonicalizing some zh locales (#6885)

resolve #6870

---------

Signed-off-by: Aaron Ruan <i@ar212.com>

src/os/i18n.zig

@@ -107,6 +107,9 @@ pub fn canonicalizeLocale(
     buf: []u8,
     locale: []const u8,
 ) error{NoSpaceLeft}![:0]const u8 {
+    // Fix zh locales for macOS
+    if (fixZhLocale(locale)) |fixed| return fixed;
+
     // Buffer must be 16 or at least as long as the locale and null term
     if (buf.len < @max(16, locale.len + 1)) return error.NoSpaceLeft;
 
@@ -125,6 +128,30 @@ pub fn canonicalizeLocale(
     return buf[0..slice.len :0];
 }
 
+/// Handles some zh locales canonicalization because internal libintl
+/// canonicalization function doesn't handle correctly in these cases.
+fn fixZhLocale(locale: []const u8) ?[:0]const u8 {
+    var it = std.mem.splitScalar(u8, locale, '-');
+    const name = it.next() orelse return null;
+    if (!std.mem.eql(u8, name, "zh")) return null;
+
+    const script = it.next() orelse return null;
+    const region = it.next() orelse return null;
+
+    if (std.mem.eql(u8, script, "Hans")) {
+        if (std.mem.eql(u8, region, "SG")) return "zh_SG";
+        return "zh_CN";
+    }
+
+    if (std.mem.eql(u8, script, "Hant")) {
+        if (std.mem.eql(u8, region, "MO")) return "zh_MO";
+        if (std.mem.eql(u8, region, "HK")) return "zh_HK";
+        return "zh_TW";
+    }
+
+    return null;
+}
+
 /// This can be called at any point a compile-time-known locale is
 /// available. This will use comptime to verify the locale is supported.
 pub fn staticLocale(comptime v: [*:0]const u8) [*:0]const u8 {
@@ -159,6 +186,12 @@ test "canonicalizeLocale darwin" {
     try testing.expectEqualStrings("zh_CN", try canonicalizeLocale(&buf, "zh-Hans"));
     try testing.expectEqualStrings("zh_TW", try canonicalizeLocale(&buf, "zh-Hant"));
 
+    try testing.expectEqualStrings("zh_CN", try canonicalizeLocale(&buf, "zh-Hans-CN"));
+    try testing.expectEqualStrings("zh_SG", try canonicalizeLocale(&buf, "zh-Hans-SG"));
+    try testing.expectEqualStrings("zh_TW", try canonicalizeLocale(&buf, "zh-Hant-TW"));
+    try testing.expectEqualStrings("zh_HK", try canonicalizeLocale(&buf, "zh-Hant-HK"));
+    try testing.expectEqualStrings("zh_MO", try canonicalizeLocale(&buf, "zh-Hant-MO"));
+
     // This is just an edge case I want to make sure we're aware of:
     // canonicalizeLocale does not handle encodings and will turn them into
     // underscores. We should parse them out before calling this function.