sizeof() and #if

[Jack Jansen]

I while ago, I tried something that I was almost sure would
fail (which it did), being:

#if sizeof(struct foobar) != BLKSIZ

I *know* why this fails, but still the most recent definition
I saw of #if is
#if <constant-expression>
which includes sizeof().
Does anyone know whether the new standard has changed this, or
changed the definition of constant-expression not to include
sizeof()?
Or is everyone supposed to integrate the preprocessor into the
compiler (yuck)?
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