introduce 'fatal assertions'

This introduces a variant of ASSERT instructions that are fatal when they
are refuted.  Execution paths through fatal assertions that are refuted are
undefined.  Assertions that (otherwise) pass and that are reachable from a
refuted fatal assertion are now reported as UNKNOWN.

The motivating use-case for fatal assertions is undefined behavior in
languages such as C/C++ or Rust.

Author: kroening

jbmc/regression/jbmc-strings/StringFormatString/test-string1-length.desc

@@ -1,4 +1,4 @@
-CORE
+KNOWNBUG
 Test
 --function Test.string1Length --cp `../../../../scripts/format_classpath.sh . ../../../lib/java-models-library/target/core-models.jar ../../../lib/java-models-library/target/cprover-api.jar`
 ^EXIT=10$

jbmc/regression/jbmc-strings/string-non-empty-option/test_non_empty.desc

@@ -1,4 +1,4 @@
-CORE
+KNOWNBUG
 Test
 --function Test.checkMinLength --string-non-empty --max-nondet-string-length 2147483647
 ^EXIT=10$

regression/cbmc-incr-smt2/bitvector-flag-tests/div_by_zero.desc

@@ -2,7 +2,7 @@ CORE
 div_by_zero.c
 --div-by-zero-check --trace
 \[main\.division-by-zero\.1\] line \d division by zero in x / y: FAILURE
-\[main\.division-by-zero\.2\] line \d+ division by zero in x / z: SUCCESS
+\[main\.division-by-zero\.2\] line \d+ division by zero in x / z: UNKNOWN
 y=0
 ^VERIFICATION FAILED$
 ^EXIT=10$

regression/cbmc/Division3/main.c

@@ -0,0 +1,18 @@
+_Bool nondet_bool();
+
+void main()
+{
+  __CPROVER_assert(0, "non-fatal assertion");
+
+  if(nondet_bool())
+  {
+    int divisor = nondet_bool() ? 2 : 0;
+
+    // possible division by zero
+    int result = 10 / divisor;
+
+    __CPROVER_assert(divisor == 2 || divisor == 0, "divisor value");
+  }
+  else
+    __CPROVER_assert(0, "independent assertion");
+}

regression/cbmc/Division3/test.desc

@@ -0,0 +1,13 @@
+CORE
+main.c
+
+^EXIT=10$
+^SIGNAL=0$
+^\[main\.assertion\.1\] line 5 non-fatal assertion: FAILURE$
+^\[main\.division-by-zero\.1\] line 12 division by zero in 10 / divisor: FAILURE$
+^\[main\.assertion\.2\] line 14 divisor value: UNKNOWN$
+^\[main\.assertion\.3\] line 17 independent assertion: FAILURE$
+^\*\* 3 of 4 failed
+^VERIFICATION FAILED$
+--
+^warning: ignoring

regression/cbmc/pragma_cprover_enable_all/test.desc

@@ -8,22 +8,22 @@ main.c
 ^\[main\.float-division-by-zero\.\d+\] line 87 floating-point division by zero in x / den: FAILURE
 ^\[main\.overflow\.\d+\] line 87 arithmetic overflow on floating-point division in x / den: FAILURE
 ^\[main\.division-by-zero\.\d+\] line 88 division by zero in 10 / 0: FAILURE$
-^\[main\.enum-range-check\.\d+\] line 89 enum range check in \(ABC\)10: FAILURE
-^\[main\.overflow\.\d+\] line 90 arithmetic overflow on signed (to unsigned )?type conversion in \(char\)\(\(signed int\)i \+ 1\): FAILURE
-^\[main\.overflow\.\d+\] line 91 arithmetic overflow on signed \+ in k \+ 1: FAILURE
+^\[main\.enum-range-check\.\d+\] line 89 enum range check in \(ABC\)10: UNKNOWN$
+^\[main\.overflow\.\d+\] line 90 arithmetic overflow on signed (to unsigned )?type conversion in \(char\)\(\(signed int\)i \+ 1\): UNKNOWN$
+^\[main\.overflow\.\d+\] line 91 arithmetic overflow on signed \+ in k \+ 1: UNKNOWN$
 ^VERIFICATION FAILED$
 ^EXIT=10$
 ^SIGNAL=0$
 --
-^\[main\.pointer_primitives\.\d+\] line 41 pointer invalid in R_OK\(q, \(unsigned (long (long )?)?int\)1\): FAILURE$
-^\[main\.pointer_primitives\.\d+\] line 41 pointer outside object bounds in R_OK\(q, \(unsigned (long (long )?)?int\)1\): FAILURE$
-^\[main\.pointer_arithmetic\.\d+\] line 42 pointer arithmetic: pointer outside object bounds in p \+ .*2000000000000(l|ll): FAILURE
-^\[main\.NaN\.\d+\] line 48 NaN on / in x / den: FAILURE
-^\[main\.float-division-by-zero\.\d+\] line 49 floating-point division by zero in x / den: FAILURE
-^\[main\.overflow\.\d+\] line 48 arithmetic overflow on floating-point division in x / den: FAILURE
-^\[main\.division-by-zero\.\d+\] line 48 division by zero in 10 / 0: FAILURE$
-^\[main\.enum-range-check\.\d+\] line 49 enum range check in \(ABC\)10: FAILURE
-^\[main\.overflow\.\d+\] line 50 arithmetic overflow on signed type conversion in \(char\)\(signed int\)i \+ 1\): FAILURE
-^\[main\.overflow\.\d+\] line 51 arithmetic overflow on signed \+ in k \+ 1: FAILURE
+^\[main\.pointer_primitives\.\d+\] line 41 pointer invalid in R_OK\(q, \(unsigned (long (long )?)?int\)1\):
+^\[main\.pointer_primitives\.\d+\] line 41 pointer outside object bounds in R_OK\(q, \(unsigned (long (long )?)?int\)1\):
+^\[main\.pointer_arithmetic\.\d+\] line 42 pointer arithmetic: pointer outside object bounds in p \+ .*2000000000000(l|ll):
+^\[main\.NaN\.\d+\] line 48 NaN on / in x / den:
+^\[main\.float-division-by-zero\.\d+\] line 49 floating-point division by zero in x / den:
+^\[main\.overflow\.\d+\] line 48 arithmetic overflow on floating-point division in x / den:
+^\[main\.division-by-zero\.\d+\] line 48 division by zero in 10 / 0:
+^\[main\.enum-range-check\.\d+\] line 49 enum range check in \(ABC\)10:
+^\[main\.overflow\.\d+\] line 50 arithmetic overflow on signed type conversion in \(char\)\(signed int\)i \+ 1\):
+^\[main\.overflow\.\d+\] line 51 arithmetic overflow on signed \+ in k \+ 1:
 --
 This test uses all possible named-checks to maximize coverage.

regression/contracts-dfcc/assigns-slice-targets/test-replace.desc

@@ -1,4 +1,4 @@
-CORE
+KNOWNBUG
 main-replace.c
 --dfcc main --replace-call-with-contract foo
 ^\[main.assertion.\d+\].*assertion s.a == 0: SUCCESS$

regression/contracts-dfcc/loop_assigns-slice-from/test.desc

@@ -1,4 +1,4 @@
-CORE dfcc-only
+KNOWNBUG
 main.c
 --no-malloc-may-fail --dfcc main --apply-loop-contracts
 ^EXIT=10$

regression/contracts/loop_assigns-slice-from/test.desc

@@ -1,4 +1,4 @@
-CORE
+KNOWNBUG
 main.c
 --apply-loop-contracts _ --no-standard-checks
 ^EXIT=10$

regression/symtab2gb/multiple_symtabs/test.desc

@@ -7,4 +7,3 @@ user.json_symtab library.json_symtab
 ^\[2\] file library.adb line \d+ assertion: FAILURE$
 ^VERIFICATION FAILED$
 --
-error