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Fix logical variable shadowing program variables
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Currently, when resolving an identifier, EasyCrypt tries to resolve it
as a logical variable first, and then as a program variable (in the
active memory), even when a memory specifier is given.

This commit adds a new memory specifier that changes the resolution
order: when using it, we first try to resolve the identifier as a
program variable (in the given memory), and then as a logical variable
if no program variable matching that name is found.

The syntax if `form{!memory}`.

The pretty-printer has been updated accordingly.
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@strub
strub committed Sep 30, 2024
1 parent 9128669 commit 4f214ac
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Showing 4 changed files with 102 additions and 54 deletions.
5 changes: 4 additions & 1 deletion src/ecParser.mly
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Original file line number Diff line number Diff line change
Expand Up @@ -881,6 +881,9 @@ pside_:
pside:
| x=brace(pside_) { x }

pside_force:
| brace(b=boption(NOT) m=loc(pside_) { (b, m) }) { $1 }

(* -------------------------------------------------------------------- *)
(* Patterns *)

Expand Down Expand Up @@ -1211,7 +1214,7 @@ sform_u(P):
{ let e1 = List.reduce1 (fun _ -> lmap (fun x -> PFtuple x) e1) (unloc e1) in
pfset (EcLocation.make $startpos $endpos) ti se e1 e2 }

| x=sform_r(P) s=loc(pside)
| x=sform_r(P) s=pside_force
{ PFside (x, s) }

| op=loc(numop) ti=tvars_app?
Expand Down
2 changes: 1 addition & 1 deletion src/ecParsetree.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,7 @@ and pformula_r =
| PFident of pqsymbol * ptyannot option
| PFref of psymbol * pffilter list
| PFmem of psymbol
| PFside of pformula * symbol located
| PFside of pformula * (bool * symbol located)
| PFapp of pformula * pformula list
| PFif of pformula * pformula * pformula
| PFmatch of pformula * (ppattern * pformula) list
Expand Down
24 changes: 18 additions & 6 deletions src/ecPrinting.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -322,6 +322,7 @@ module PPEnv = struct
match EcEnv.Var.lookup_local_opt name ppe.ppe_env with
| Some (id, _) when EcIdent.id_equal id x -> name
| _ -> EcIdent.name x

let tyvar (ppe : t) x =
match Mid.find_opt x ppe.ppe_locals with
| None -> EcIdent.tostring x
Expand Down Expand Up @@ -1665,12 +1666,23 @@ and pp_form_core_r (ppe : PPEnv.t) outer fmt f =
pp_local ppe fmt id

| Fpvar (x, i) -> begin
match EcEnv.Memory.get_active ppe.PPEnv.ppe_env with
| Some i' when EcMemory.mem_equal i i' ->
Format.fprintf fmt "%a" (pp_pv ppe) x
| _ ->
let ppe = PPEnv.enter_by_memid ppe i in
Format.fprintf fmt "%a{%a}" (pp_pv ppe) x (pp_mem ppe) i
let default (force : bool) =
let ppe = PPEnv.enter_by_memid ppe i in
Format.fprintf fmt "%a{%s%a}"
(pp_pv ppe) x (if force then "!" else "") (pp_mem ppe) i in

let force =
match x with
| PVloc x -> Ssym.mem x ppe.ppe_inuse
| PVglob _ -> false in

if force then default true else

match EcEnv.Memory.get_active ppe.PPEnv.ppe_env with
| Some i' when EcMemory.mem_equal i i' ->
Format.fprintf fmt "%a" (pp_pv ppe) x
| _ ->
default false
end

| Fglob (mp, i) -> begin
Expand Down
125 changes: 79 additions & 46 deletions src/ecTyping.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -338,6 +338,7 @@ end
let gen_select_op
~(actonly : bool)
~(mode : OpSelect.mode)
~(forcepv : bool)
(opsc : path option)
(tvi : EcUnify.tvi)
(env : EcEnv.env)
Expand All @@ -348,15 +349,15 @@ let gen_select_op
: OpSelect.gopsel list
=

let fpv me (pv, ty, ue) =
let fpv me (pv, ty, ue) : OpSelect.gopsel =
(`Pv (me, pv), ty, ue, (pv :> opmatch))

and fop (op, ty, ue, bd) =
and fop (op, ty, ue, bd) : OpSelect.gopsel=
match bd with
| None -> (`Op op, ty, ue, (`Op op :> opmatch))
| Some bd -> (`Nt bd, ty, ue, (`Op op :> opmatch))

and flc (lc, ty, ue) =
and flc (lc, ty, ue) : OpSelect.gopsel =
(`Lc lc, ty, ue, (`Lc lc :> opmatch)) in

let ue_filter =
Expand All @@ -378,39 +379,52 @@ let gen_select_op

in

match (if tvi = None then select_local env name else None) with
| Some (id, ty) ->
[ flc (id, ty, ue) ]
let locals () : OpSelect.gopsel list =
if Option.is_none tvi then
select_local env name
|> Option.map
(fun (id, ty) -> flc (id, ty, ue))
|> Option.to_list
else [] in

let ops () : OpSelect.gopsel list =
let ops = EcUnify.select_op ~filter:ue_filter tvi env name ue psig in
let ops = opsc |> ofold (fun opsc -> List.mbfilter (by_scope opsc)) ops in
let ops = match List.mbfilter by_current ops with [] -> ops | ops -> ops in
let ops = match List.mbfilter by_tc ops with [] -> ops | ops -> ops in
(List.map fop ops)

and pvs () : OpSelect.gopsel list =
let me, pvs =
match EcEnv.Memory.get_active env, actonly with
| None, true -> (None, [])
| me , _ -> ( me, select_pv env me name ue tvi psig)
in List.map (fpv me) pvs
in

| None ->
let ops () =
let ops = EcUnify.select_op ~filter:ue_filter tvi env name ue psig in
let ops = opsc |> ofold (fun opsc -> List.mbfilter (by_scope opsc)) ops in
let ops = match List.mbfilter by_current ops with [] -> ops | ops -> ops in
let ops = match List.mbfilter by_tc ops with [] -> ops | ops -> ops in
(List.map fop ops)

and pvs () =
let me, pvs =
match EcEnv.Memory.get_active env, actonly with
| None, true -> (None, [])
| me , _ -> ( me, select_pv env me name ue tvi psig)
in List.map (fpv me) pvs
in
let select (filters : (unit -> OpSelect.gopsel list) list) : OpSelect.gopsel list =
List.find_map_opt
(fun f -> match f () with [] -> None | x -> Some x)
filters
|> odfl [] in

match mode with
| `Expr `InOp -> ops ()
| `Form -> (match pvs () with [] -> ops () | pvs -> pvs)
| `Expr `InProc -> (match pvs () with [] -> ops () | pvs -> pvs)
match mode with
| `Expr `InOp -> select [locals; ops]
| `Form
| `Expr `InProc ->
if forcepv then
select [pvs; locals; ops]
else
select [locals; pvs; ops]

(* -------------------------------------------------------------------- *)
let select_exp_op env mode opsc name ue tvi psig =
gen_select_op ~actonly:false ~mode:(`Expr mode)
gen_select_op ~actonly:false ~forcepv:false ~mode:(`Expr mode)
opsc tvi env name ue psig

(* -------------------------------------------------------------------- *)
let select_form_op env opsc name ue tvi psig =
gen_select_op ~actonly:true ~mode:`Form
let select_form_op env ~forcepv opsc name ue tvi psig =
gen_select_op ~actonly:true ~mode:`Form ~forcepv
opsc tvi env name ue psig

(* -------------------------------------------------------------------- *)
Expand Down Expand Up @@ -1745,23 +1759,36 @@ module PFS : sig

val set_memused : pfstate -> unit
val get_memused : pfstate -> bool
val new_memused : ('a -> 'b) -> pfstate -> 'a -> bool * 'b
val isforced : pfstate -> bool
val new_memused : ('a -> 'b) -> force:bool -> pfstate -> 'a -> bool * 'b
end = struct
type pfstate = { mutable pfa_memused : bool; }
type pfstate1 = {
pfa_memused : bool;
pfa_forced : bool;
}

let create () = { pfa_memused = true; }
type pfstate = pfstate1 ref

let set_memused state =
state.pfa_memused <- true
let create1 ~(force : bool) : pfstate1 =
{ pfa_memused = false; pfa_forced = force; }

let get_memused state =
state.pfa_memused
let create () : pfstate =
ref (create1 ~force:false)

let new_memused f state x =
let old = state.pfa_memused in
let aout = (state.pfa_memused <- false; f x) in
let new_ = state.pfa_memused in
state.pfa_memused <- old; (new_, aout)
let set_memused (state : pfstate) =
state := { !state with pfa_memused = true }

let get_memused (state : pfstate) =
(!state).pfa_memused

let isforced (state : pfstate) =
(!state).pfa_forced

let new_memused (f : 'a -> 'b) ~(force : bool) (state : pfstate) (x : 'a) =
let old = !state in
let aout = (state := create1 ~force; f x) in
let new_ = get_memused state in
state := old; (new_, aout)
end

(* -------------------------------------------------------------------- *)
Expand Down Expand Up @@ -3026,7 +3053,10 @@ and trans_form_or_pattern env ?mv ?ps ue pf tt =

| PFident ({ pl_desc = name; pl_loc = loc }, tvi) ->
let tvi = tvi |> omap (transtvi env ue) in
let ops = select_form_op env opsc name ue tvi [] in
let ops =
select_form_op
~forcepv:(PFS.isforced state)
env opsc name ue tvi [] in
begin match ops with
| [] ->
tyerror loc env (UnknownVarOrOp (name, []))
Expand All @@ -3045,7 +3075,7 @@ and trans_form_or_pattern env ?mv ?ps ue pf tt =
tyerror loc env (MultipleOpMatch (name, [], matches))
end

| PFside (f, side) -> begin
| PFside (f, (force, side)) -> begin
let (sloc, side) = (side.pl_loc, unloc side) in
let me =
match EcEnv.Memory.lookup side env with
Expand All @@ -3056,7 +3086,7 @@ and trans_form_or_pattern env ?mv ?ps ue pf tt =
let used, aout =
PFS.new_memused
(transf (EcEnv.Memory.set_active me env))
state f
~force state f
in
if not used then begin
let ppe = EcPrinting.PPEnv.ofenv env in
Expand Down Expand Up @@ -3139,11 +3169,11 @@ and trans_form_or_pattern env ?mv ?ps ue pf tt =
let _, f1 =
PFS.new_memused
(transf (EcEnv.Memory.set_active me1 env))
state f in
~force:false state f in
let _, f2 =
PFS.new_memused
(transf (EcEnv.Memory.set_active me2 env))
state f in
~force:false state f in
unify_or_fail env ue f.pl_loc ~expct:f1.f_ty f2.f_ty;
f_eq f1 f2

Expand All @@ -3156,7 +3186,10 @@ and trans_form_or_pattern env ?mv ?ps ue pf tt =
let tvi = tvi |> omap (transtvi env ue) in
let es = List.map (transf env) pes in
let esig = List.map EcFol.f_ty es in
let ops = select_form_op env opsc name ue tvi esig in
let ops =
select_form_op ~forcepv:(PFS.isforced state)
env opsc name ue tvi esig in

begin match ops with
| [] ->
let uidmap = UE.assubst ue in
Expand Down

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