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Re: Incomplete TREE_CONSTANT-propagation in build() ?
On Wed, 5 Nov 2003, Gabriel Dos Reis wrote:
> I'm not sure he was proposing to change TREE_CONSTANT as opposed to
> extending it. My understanding is that he would like to have it cover
> more cases. Or, are you saying that his proposed extension would
> break things?
I'm suggesting that changing (the value of) TREE_CONSTANT (for these
expressions) might break code using it to approximate whether something is
a constant expression, because of the dual use at present.
> | On the separate matter of delaying folding these expressions, I suspect
> | delaying all folding beyond that actually required for integer constant
> | expressions, until a full expression is obtained, would be a good idea.
>
> Yes. And given that COMPOUND_EXPRs ar enot constant expressions, that
> won't do any harm.
It might break uses of the undocumented extensions whereby certain things,
that shouldn't be constant expressions, are treated as such. Since all
those extensions are undocumented and liable to be removed without warning
or deprecation period, I don't consider this a problem.
--
Joseph S. Myers
jsm@polyomino.org.uk