[isabelle-dev] Regression in the sublocale command

[Clemens Ballarin]

Hi Florian,

I'm investigating a regression which prevents identifying certain equivalent locales through circular sublocale declarations:

  sublocale loc1 < x: loc2 A c (* sigma_1 *)
    where "x.b == B" and "x.d == e" (* tau_1 *)
  sorry

  sublocale loc2 < x: loc1 A b (* sigma_2 *)
    where "x.c == C" and "x.e == d" (* tau_2 *)
  sorry (* loops from changeset 8fab871a2a6f *)

The last "sorry" loops, which is unfortunate, because it forces certain workarounds on my current project.  In a fairly lengthy debug session I figured out that it is the simplifier that loops.  This is an indication that the morphisms tau_1 and tau_2 are applied simultaneously, which they should not.  In any case, the behaviour appears to have been introduced quite a while ago in 8fab871a2a6f, which is in the first batch of your changes to the locale interpretation commands.

Clemens