// have been found earlier.
		if t.RegionID != 0 {
			if i := regionInclusion[t.RegionID]; i < nRegionGroups {
				x := likelyRegionGroup[i]
				if x.region != 0 {
					t.setUndefinedLang(Language(x.lang))
					t.setUndefinedScript(Script(x.script))
					t.RegionID = Region(x.region)
				}
			} else {
				x := likelyRegion[t.RegionID]
				if x.flags&isList != 0 {
					x = likelyRegionList[x.lang]

		return 0, false
	}
	cci |= CompactCoreInfo(t.LangID) << (8 + 12)
	cci |= CompactCoreInfo(t.ScriptID) << 12
	cci |= CompactCoreInfo(t.RegionID)
	return cci, true
}

// Tag generates a tag from c.
func (c CompactCoreInfo) Tag() Tag {
	return Tag{
		LangID:   Language(c >> 20),
		RegionID: Region(c & 0x3ff),
		ScriptID: Script(c>>12) & 0xff,
	}

			tFull := t
			t, _ = t.SetTypeForKey("rg", "")
			// TODO: should we not consider "va" for the language tag?
			var exact1, exact2 bool
			tag.language, exact1 = FromTag(t)
			t.RegionID = r
			tag.locale, exact2 = FromTag(t)
			if !exact1 || !exact2 {
				tag.full = tFull
			}
			return tag
		}
	}
	lang, ok := FromTag(t)
	tag.language = lang
	tag.locale = lang
	if !ok {

		t.RemakeString()
	}
	return t
}

// SetTag copies all the settings from a given Tag. Any previously set values
// are discarded.
func (b *Builder) SetTag(t Tag) {
	b.Tag.LangID = t.LangID
	b.Tag.RegionID = t.RegionID
	b.Tag.ScriptID = t.ScriptID
	// TODO: optimize
	b.variants = b.variants[:0]
	if variants := t.Variants(); variants != "" {
		for _, vr := range strings.Split(variants[1:], "-") {

	for _, x := range part {
		switch v := x.(type) {
		case Tag:
			b.SetTag(v.tag())
		case Base:
			b.Tag.LangID = v.langID
		case Script:
			b.Tag.ScriptID = v.scriptID
		case Region:
			b.Tag.RegionID = v.regionID
		case Variant:
			if v.variant == "" {
				err = errInvalidArgument
				break
			}
			b.AddVariant(v.variant)
		case Extension:
			if v.s == "" {
				err = errInvalidArgument
				break