silver/src/test/resources/termination/functions/expressions/exists.vpr at 361caeae5fb89fac9ab8b93de09e60860419e519 · viperproject/silver · GitHub

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// Any copyright is dedicated to the Public Domain.
// http://creativecommons.org/publicdomain/zero/1.0/

import <decreases/declaration.vpr>

field f: Int

function test(x: Ref): Bool
    decreases
{
    //:: ExpectedOutput(termination.failed:termination.condition.false)
    exists x2: Ref :: x == x2 && nonTerminating(x2)
}

function test2(): Bool
    decreases
{
    // in general `partiallyTerminating` is non-terminating
    //:: ExpectedOutput(termination.failed:termination.condition.false)
    exists x2: Int :: partiallyTerminating(x2)
}

function test3(x: Int): Bool
    decreases
    requires x == 42
{
    // `partiallyTerminating` terminates for input `42` so this is fine
    exists x2: Int :: x == x2 && partiallyTerminating(x2)
}

function test4(x: Int): Bool
    decreases
{
    // in general `partiallyTerminating` is non-terminating
    //:: ExpectedOutput(termination.failed:termination.condition.false)
    (exists x2: Int :: x == x2) && partiallyTerminating(x)
}

function test5(x: Int): Bool
    decreases
{
    // this is fine due to short-circuiting
    (exists x2: Int :: x == x2 && x != x2) && partiallyTerminating(x)
}

function nonTerminating(x: Ref): Bool
    decreases *

function partiallyTerminating(x: Int): Bool
    decreases if x == 42
    decreases *