From 2099972f4110e06db8b6452d4511b991efb896c7 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Fri, 20 Jul 2018 09:05:58 +0200 Subject: [PATCH 1/1] more information on determinism of CTFE --- personal/_posts/2018-07-19-const.md | 1 + 1 file changed, 1 insertion(+) diff --git a/personal/_posts/2018-07-19-const.md b/personal/_posts/2018-07-19-const.md index 23e9325..2bcd009 100644 --- a/personal/_posts/2018-07-19-const.md +++ b/personal/_posts/2018-07-19-const.md @@ -39,6 +39,7 @@ Clearly, we don't want CTFE to have actually observable side-effects outside of In fact, just naively letting programs read files would also be grossly unsafe: When computing the length of an array twice, it is important that we obtain the same result. +**Update:** As @eddyb points out, things get even worse once you consider const generics, traits, and coherence: At that point, you have to [rely on evaluating the same expression in different crates to produce the same result](https://internals.rust-lang.org/t/mir-constant-evaluation/3143/47). **/Update** > *CTFE must be deterministic.* -- 2.30.2