ill-typed alt-ergo proof obligation
ID0001484: This issue was created automatically from Mantis Issue 1484. Further discussion may take place here.
| Id | Project | Category | View | Due Date | Updated |
|---|---|---|---|---|---|
| ID0001484 | Frama-C | Plug-in > wp | public | 2013-09-25 | 2020-02-17 |
| Reporter | virgile | Assigned To | correnson | Resolution | fixed |
| Priority | normal | Severity | minor | Reproducibility | always |
| Platform | - | OS | - | OS Version | - |
| Product Version | Frama-C GIT, precise the release id | Target Version | - | Fixed in Version | Frama-C 20-Calcium |
Description :
Using WP with RTE enabled on the attached file results in proof obligations rejected as ill-typed by Alt-Ergo.
Additional Information :
Without rte, everything is fine. With RTE, the resulting proof obligation is the following:
forall x_0 : int. let x_1 = to_sint32(neqb(0, x_0)) : int in let x_2 = to_uint8(x_0 - (ite((eqb(0, x_0)), 0, 1))) : int in is_uint8(x_0) -> (x_1 <= (2147483648 + x_0)) -> (x_0 <= (2147483647 + x_1)) -> is_uint8(x_2) -> (x_2 <= x_0)
the definition of x_1 is lacking an ite(_,0,1) conversion, as shown in the definition of x_2. x_1 does not appear in the PO without RTE, as it is only used in the (x<=2147483648 + x_0) and x_0 <= (2147483647 + x_1) hypotheses reflecting the RTE-generated hypotheses. Note that writing the RTE-generated hypotheses in the code (and launching WP without -wp-rte) results in warning cast from (boolean) not yet implemented, and degenerated goals.
Steps To Reproduce :
frama-c -wp -wp-rte t.c