# 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