Implicit casting from integer to real causes failure in WP proof generation
ID0002241: This issue was created automatically from Mantis Issue 2241. Further discussion may take place here.
| Id | Project | Category | View | Due Date | Updated |
|---|---|---|---|---|---|
| ID0002241 | Frama-C | Plug-in > wp | public | 2016-07-29 | 2016-07-29 |
| Reporter | jrobbins | Assigned To | correnson | Resolution | open |
| Priority | normal | Severity | major | Reproducibility | always |
| Platform | - | OS | - | OS Version | - |
| Product Version | Frama-C Aluminium | Target Version | - | Fixed in Version | - |
Description :
ACSL defines the integer type as a subset of the real type. Therefore, it states, implicit casting from integers to reals is allowed, because one is the subset of another. However, when this is done in practice, the WP plugin will generate goals that provers cannot parse, giving a type error.
Additional Information :
This is confirmed to occur with the alt-ergo and why3 provers.
Tested on both Frama-C Sodium and Aluminum. Sodium produces slightly different errors than Aluminum, but both produce errors.
Steps To Reproduce :
== Input file (bug.c):
/*@ axiomatic Bug { logic integer ibug; logic real rbug = ibug; } */
/*@ requires i == rbug; */ void foo(int i);
void main() { foo(42); }
== Command to reproduce
frama-c -wp bug.c
== Output
[kernel] Parsing FRAMAC_SHARE/libc/__fc_builtin_for_normalization.i (no preprocessing) [kernel] Parsing bug.c (with preprocessing) bug.c:13:[kernel] warning: No code nor implicit assigns clause for function foo, generating default assigns from the prototype [wp] warning: Missing RTE guards [wp] 1 goal scheduled /tmp/wp714796.dir/typed/A_Bug.ergo:7:[wp] user error: Alt-Ergo error: characters 1-34:typing error: real and int cannot be unified [wp] [Alt-Ergo] Goal typed_main_call_foo_pre : Failed characters 1-34:typing error: real and int cannot be unified [wp] Proved goals: 0 / 1 Alt-Ergo: 0 (failed: 1)