Let definitions must not contain side-effects when reaching the kernel.

Let definitions have the same behaviour if they are ended with a Qed or a
Defined command, i.e. they are treated as if they were transparent. Indeed,
it doesn't make sense for them to be opaque as they are going to be expanded
away at the end of the section.

For an unknown reason, handling of side-effects in Let definitions considers
them as if they were opaque, i.e. the effects are inlined in the definition.

This discrepancy has bad consequences in the kernel, where one is forced to
juggle with universe constraints generated by polymorphic Let definitions.
As a first phase of cleaning, we simply enforce by typing that Let definitions
should be purified before reaching the kernel.

This has the intended side-effect to make side-effects persistent in Let
definitions, as if they were indeed truly transparent.

1 files changed, 1 insertions, 2 deletions

diff --git a/kernel/safe_typing.ml b/kernel/safe_typing.ml
index 5150ad411..fa984515a 100644
--- a/kernel/safe_typing.ml
+++ b/kernel/safe_typing.ml
@@ -383,8 +383,7 @@ let safe_push_named d env =
 
 let push_named_def (id,de) senv =
   let open Entries in
-  let trust = Term_typing.SideEffects senv.revstruct in
-  let c,typ,univs = Term_typing.translate_local_def trust senv.env id de in
+  let c,typ,univs = Term_typing.translate_local_def senv.env id de in
   let poly = match de.Entries.const_entry_universes with
   | Monomorphic_const_entry _ -> false
   | Polymorphic_const_entry _ -> true