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module TestModule {
copredicate P(b: bool)
{
!b && Q(null)
}
copredicate Q(a: array<int>)
{
a == null && P(true)
}
copredicate S(d: set<int>)
{
this.Undeclared#[5](d) && // error: 'Undeclared#' is undeclared
Undeclared#[5](d) && // error: 'Undeclared#' is undeclared
this.S#[5](d) &&
S#[5](d) &&
S#[_k](d) // error: _k is not an identifier in scope
}
comethod CM(d: set<int>)
{
var b;
b := this.S#[5](d);
b := S#[5](d);
this.CM#[5](d);
CM#[5](d);
}
}
module GhostCheck0 {
codatatype Stream<G> = Cons(head: G, tail: Stream);
method UseStream0(s: Stream)
{
var x := 3;
if (s == s.tail) { // error: this operation is allowed only in ghost contexts
x := x + 2;
}
}
}
module GhostCheck1 {
codatatype Stream<G> = Cons(head: G, tail: Stream);
method UseStream1(s: Stream)
{
var x := 3;
if (s ==#[20] s.tail) { // this seems innocent enough, but it's currently not supported by the compiler, so...
x := x + 7; // error: therefore, this is an error
}
}
}
module GhostCheck2 {
codatatype Stream<G> = Cons(head: G, tail: Stream);
ghost method UseStreamGhost(s: Stream)
{
var x := 3;
if (s == s.tail) { // fine
x := x + 2;
}
}
}
module Mojul0 {
copredicate D()
reads this; // error: copredicates are not allowed to have a reads clause -- WHY NOT?
{
true
}
copredicate NoEnsuresPlease(m: nat)
ensures NoEnsuresPlease(m) ==> m < 100; // error: a copredicate is not allowed to have an 'ensures' clause
{
m < 75
}
// Note, 'decreases' clauses are also disallowed on copredicates, but the parser takes care of that
}
module Mojul1 {
copredicate A() { B() } // error: SCC of a copredicate must include only copredicates
predicate B() { A() }
copredicate X() { Y() }
copredicate Y() { X#[10]() } // error: X is not allowed to depend on X#
comethod M()
{
N();
}
comethod N()
{
Z();
W(); // error: not allowed to make co-recursive call to non-comethod
}
ghost method Z() { }
ghost method W() { M(); }
comethod G() { H(); }
comethod H() { G#[10](); } // fine for comethod/prefix-method
}
module CallGraph {
// comethod -> copredicate -> comethod
// comethod -> copredicate -> prefix method
comethod CoLemma(n: nat)
{
var q := Q(n); // error
var r := R(n); // error
}
copredicate Q(n: nat)
{
calc { 87; { CoLemma(n); } }
false
}
copredicate R(n: nat)
{
calc { 87; { CoLemma#[n](n); } }
false
}
// comethod -> prefix predicate -> comethod
// comethod -> prefix predicate -> prefix method
comethod CoLemma_D(n: nat)
{
var q := Q_D#[n](n); // error
var r := R_D#[n](n); // error
}
copredicate Q_D(n: nat)
{
calc { 88; { CoLemma_D(n); } }
false
}
copredicate R_D(n: nat)
{
calc { 89; { CoLemma_D#[n](n); } }
false
}
// copredicate -> function -> copredicate
// copredicate -> function -> prefix predicate
copredicate P(n: nat)
{
G0(n) // error
<
G1(n) // error
}
function G0(n: nat): int
{
calc { true; { assert P(n); } }
100
}
function G1(n: nat): int
{
calc { true; { assert P#[n](n); } }
101
}
}
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