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Merge pull request #8562 from remi-delmas-3000/contracts-allow-is-fresh-to-fail
CONTRACTS: allow pointer predicates to fail in `assume` contexts
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‎doc/man/cbmc.1‎

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@@ -334,6 +334,13 @@ set malloc failure mode to return null
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\fB\-\-string\-abstraction\fR
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track C string lengths and zero\-termination
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.TP
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\fB\-\-dfcc\-debug\-lib\fR
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enable debug assertions in the cprover contracts library
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.TP
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\fB\-\-dfcc\-simple\-invalid\-pointer\-model\fR
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use simplified invalid pointer model in the cprover contracts library
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(faster, unsound)
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.TP
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\fB\-\-reachability\-slice\fR
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remove instructions that cannot appear on a trace
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from entry point to a property

‎doc/man/goto-analyzer.1‎

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@@ -585,6 +585,13 @@ set malloc failure mode to return null
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.TP
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\fB\-\-string\-abstraction\fR
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track C string lengths and zero\-termination
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.TP
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\fB\-\-dfcc\-debug\-lib\fR
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enable debug assertions in the cprover contracts library
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.TP
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\fB\-\-dfcc\-simple\-invalid\-pointer\-model\fR
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use simplified invalid pointer model in the cprover contracts library
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(faster, unsound)
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.SS "Standard Checks"
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From version \fB6.0\fR onwards, \fBcbmc\fR, \fBgoto-analyzer\fR and some other tools
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apply some checks to the program by default (called the "standard checks"), with the

‎doc/man/goto-instrument.1‎

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@@ -706,6 +706,13 @@ do not allow malloc calls to fail by default
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\fB\-\-string\-abstraction\fR
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track C string lengths and zero\-termination
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.TP
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\fB\-\-dfcc\-debug\-lib\fR
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enable debug assertions in the cprover contracts library
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.TP
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\fB\-\-dfcc\-simple\-invalid\-pointer\-model\fR
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use simplified invalid pointer model in the cprover contracts library
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(faster, unsound)
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.TP
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\fB\-\-model\-argc\-argv\fR \fIn\fR
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Create up to \fIn\fR non-deterministic C strings as entries to \fIargv\fR and
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set \fIargc\fR accordingly. In absence of such modelling, \fIargv\fR is left

‎regression/contracts-dfcc/quantifiers-loops-fresh-bound-vars-smt/test.desc‎

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@@ -1,4 +1,4 @@
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CORE dfcc-only smt-backend broken-cprover-smt-backend
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FUTURE dfcc-only smt-backend broken-cprover-smt-backend
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main.c
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--dfcc main --apply-loop-contracts --enforce-contract foo --malloc-may-fail --malloc-fail-null _ --z3 --slice-formula --no-standard-checks
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^EXIT=0$
@@ -7,6 +7,12 @@ main.c
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--
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^warning: ignoring
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--
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Marked as FUTURE because:
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- z3 >v4.12 and up can solve the problem with `--dfcc-simple-invalid-pointer-model`,
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but the CI uses older versions;
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- bitwuzla >v0.6 can solve the problem but we don't run bitwuzla in CI.
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Tests support for quantifiers in loop contracts with the SMT backend.
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When quantified loop invariants are used, they are inserted three times
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in the transformed program (base case assertion, step case assumption,

‎regression/contracts-dfcc/test_is_fresh_enforce_requires_disjunction_fail/main.c‎

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void foo(int *x)
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// clang-format off
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__CPROVER_requires(__CPROVER_is_fresh(x, sizeof(int)) || 1)
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__CPROVER_assigns(*x)
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// clang-format on
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{
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*x = 0;
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}
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void main()
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{
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int *x;
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foo(x);
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}

‎regression/contracts-dfcc/test_is_fresh_enforce_requires_disjunction_fail/test.desc‎

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CORE dfcc-only
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main.c
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--dfcc main --enforce-contract foo
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^\[__CPROVER_contracts_car_set_insert.assertion.\d+\] line \d+ ptr NULL or writable up to size: (FAILURE|UNKNOWN)$
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^\[__CPROVER_contracts_write_set_check_assignment.assertion.\d+\] line \d+ ptr NULL or writable up to size: (FAILURE|UNKNOWN)$
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^\[foo.assigns.\d+\] line \d+ Check that \*x is assignable: (FAILURE|UNKNOWN)$
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^\[foo.pointer_dereference.\d+\] line \d+ dereference failure: pointer NULL in \*x: (FAILURE|UNKNOWN)
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^\[foo.pointer_dereference.\d+\] line \d+ dereference failure: pointer invalid in \*x: (FAILURE|UNKNOWN)$
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^\[foo.pointer_dereference.\d+\] line \d+ dereference failure: deallocated dynamic object in \*x: (FAILURE|UNKNOWN)
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^\[foo.pointer_dereference.\d+\] line \d+ dereference failure: dead object in \*x: (FAILURE|UNKNOWN)
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^\[foo.pointer_dereference.\d+\] line \d+ dereference failure: pointer outside object bounds in \*x: (FAILURE|UNKNOWN)
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^\[foo.pointer_dereference.\d+\] line \d+ dereference failure: invalid integer address in \*x: (FAILURE|UNKNOWN)$
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^EXIT=10$
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^SIGNAL=0$
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^VERIFICATION FAILED$
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--
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--
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This test checks that when `__CPROVER_is_fresh` is used in disjunctions,
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the program accepts models where `__CPROVER_is_fresh` evaluates to false
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and no object gets allocated, and pointers remain invalid.

‎regression/contracts-dfcc/test_is_fresh_enforce_requires_disjunction_pass/main.c‎

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#include <stdlib.h>
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void foo(int *x, int *y)
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// clang-format off
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__CPROVER_requires(
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(__CPROVER_is_fresh(x, sizeof(*x)) && y == NULL) ||
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(x == NULL && __CPROVER_is_fresh(y, sizeof(*y)))
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)
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__CPROVER_assigns(y == NULL: *x)
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__CPROVER_assigns(x == NULL: *y)
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// clang-format on
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{
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if(y == NULL)
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{
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assert(0);
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*x = 0;
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}
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else
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{
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assert(0);
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assert(x == NULL);
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*y = 0;
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}
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}
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void main()
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{
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int *x;
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int *y;
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foo(x, y);
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}

‎regression/contracts-dfcc/test_is_fresh_enforce_requires_disjunction_pass/test.desc‎

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CORE dfcc-only
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main.c
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--dfcc main --enforce-contract foo
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^\[foo.assertion.\d+\] line 14 assertion 0: FAILURE$
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^\[foo.assigns.\d+\] line 15 Check that \*x is assignable: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 15 dereference failure: pointer NULL in \*x: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 15 dereference failure: pointer invalid in \*x: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 15 dereference failure: deallocated dynamic object in \*x: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 15 dereference failure: dead object in \*x: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 15 dereference failure: pointer outside object bounds in \*x: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 15 dereference failure: invalid integer address in \*x: SUCCESS$
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^\[foo.assertion.\d+\] line 19 assertion 0: FAILURE$
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^\[foo.assertion.\d+\] line 20 assertion x == \(\(.*\)NULL\): SUCCESS$
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^\[foo.assigns.\d+\] line 21 Check that \*y is assignable: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 21 dereference failure: pointer NULL in \*y: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 21 dereference failure: pointer invalid in \*y: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 21 dereference failure: deallocated dynamic object in \*y: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 21 dereference failure: dead object in \*y: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 21 dereference failure: pointer outside object bounds in \*y: SUCCESS$
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^\[foo.pointer_dereference.\d+\] line 21 dereference failure: invalid integer address in \*y: SUCCESS$
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^EXIT=10$
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^SIGNAL=0$
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^VERIFICATION FAILED$
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--
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--
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Illustrates the behaviour of `__CPROVER_is_fresh` under disjunctions in assume contexts.
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The precondition of `foo` describes a disjunction of cases, either `x` is fresh and `y` is null,
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or `x` is null and `y` is fresh. The function `foo` branches on `y == NULL`.
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The test suceeds if the two `assert(0)` in `foo` are falsifiable, which which shows
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that both cases of the disjunction expressed in the requires clause are reachable.

‎regression/contracts-dfcc/test_is_fresh_replace_ensures_disjunction_fail/main.c‎

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int *foo()
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// clang-format off
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__CPROVER_ensures(
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__CPROVER_is_fresh(__CPROVER_return_value, sizeof(int)) || 1);
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// clang-format on
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void bar()
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{
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int *x = foo();
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*x = 0; //expected to fail
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}
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void main()
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{
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bar();
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}

‎regression/contracts-dfcc/test_is_fresh_replace_ensures_disjunction_fail/test.desc‎

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CORE dfcc-only
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main.c
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--dfcc main --replace-call-with-contract foo
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^\[bar.pointer_dereference.\d+\] line 10 dereference failure: pointer NULL in \*x: (UNKNOWN|FAILURE)$
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^\[bar.pointer_dereference.\d+\] line 10 dereference failure: pointer invalid in \*x: (UNKNOWN|FAILURE)$
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^\[bar.pointer_dereference.\d+\] line 10 dereference failure: deallocated dynamic object in \*x: (UNKNOWN|FAILURE)$
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^\[bar.pointer_dereference.\d+\] line 10 dereference failure: dead object in \*x: (UNKNOWN|FAILURE)$
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^\[bar.pointer_dereference.\d+\] line 10 dereference failure: pointer outside object bounds in \*x: (UNKNOWN|FAILURE)$
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^\[bar.pointer_dereference.\d+\] line 10 dereference failure: invalid integer address in \*x: (UNKNOWN|FAILURE)$
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^EXIT=10$
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^SIGNAL=0$
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^VERIFICATION FAILED$
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--
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--
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This test checks that when `__CPROVER_is_fresh` is used in disjunctions,
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the program accepts models where `__CPROVER_is_fresh` evaluates to false
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and no object gets allocated, and pointers remain invalid.

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