From 17a0dccfe91d6f837ce285e62b8d843720f8c1a1 Mon Sep 17 00:00:00 2001 From: Gaëtan Gilbert Date: Fri, 16 Feb 2018 15:44:44 +0100 Subject: Allow using cumulativity without forcing strict constraints. Previously [fun x : Ind@{i} => x : Ind@{j}] with Ind some cumulative inductive would try to generate a constraint [i = j] and use cumulativity only if this resulted in an inconsistency. This is confusingly different from the behaviour with [Type] and means cumulativity can only be used to lift between universes related by strict inequalities. (This isn't a kernel restriction so there might be some workaround to send the kernel the right constraints, but not in a nice way.) See modified test for more details of what is now possible. Technical notes: When universe constraints were inferred by comparing the shape of terms without reduction, cumulativity was not used and so too-strict equality constraints were generated. Then in order to use cumulativity we had to make this comparison fail to fall back to full conversion. When unifiying 2 instances of a cumulative inductive type, if there are any Irrelevant universes we try to unify them if they are flexible. --- vernac/obligations.ml | 1 - 1 file changed, 1 deletion(-) (limited to 'vernac/obligations.ml') diff --git a/vernac/obligations.ml b/vernac/obligations.ml index 4f16e1cf6..064e40b9b 100644 --- a/vernac/obligations.ml +++ b/vernac/obligations.ml @@ -1,5 +1,4 @@ open Printf -open Globnames open Libobject open Entries open Decl_kinds -- cgit v1.2.3