Implement constant folding in the frontend

[steveklabnik]

Issue by pcwalton
Tuesday Jul 16, 2013 at 22:22 GMT

For earlier discussion, see rust-lang/rust#7834

This issue was labelled with: A-codegen, B-RFC, I-compiletime in the Rust repository

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We should be able to do constant folding in the frontend to eliminate "if" conditions that are never executed. It would also be nice to be able to call size_of at compile time in constants. (This latter part is an RFC.)

[reem]

@steveklabnik this really seems like it should belong in the rust repo, since this is basically just a codegen enhancement/bug.

[steveklabnik]

I read this as more than that, given the second part of the message here. calling size_of at compile time is certainly an RFC-worthy topic.

[Centril]

https://doc.rust-lang.org/nightly/std/mem/fn.size_of.html is today a const fn, so this is done. Closing therefore.