This should be LazyInitialized instead of explicit static cctor which we won't be able easily remove

I am fine with using some Lazy<T> initialization and / or putting that inside DoStrictParse().

However, the field initializer that this code was previously using has to go away.

The general rule here is that the pattern new SomeDelegate (ConditionalMethod) must not be used outside a linker conditional (like for instance GlobalizationMode.Invariant), so you cannot put it into a field initializer. The linker is unable to "go inside" that delegate initialization and we also don't have full support for dead field elimination yet.

That's what I meant. You keep only internal static MatchNumberDelegate m_hebrewNumberParser; with LazyInitializer.EnsureInitialized (ref m_hebrewNumberParser, ...) inside DoStrictParse

Like this:

            if (!GlobalizationMode.Invariant && (CalendarId)parseInfo.calendar.ID == CalendarId.HEBREW)
            {
                LazyInitializer.EnsureInitialized (ref m_hebrewNumberParser, () => new MatchNumberDelegate(DateTimeParse.MatchHebrewDigits));
                parseInfo.parseNumberDelegate = m_hebrewNumberParser;
                parseInfo.fCustomNumberParser = true;
            }

or do we need locking?

yep, EnsureInitialized is thread-safe

Okay, done.