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  • #1818

Closed
Open
Created Nov 08, 2013 by Virgile Prevosto@virgileOwner

unprovable PO in function manipulating structs - issue with Qed's simplifications

ID0001556: This issue was created automatically from Mantis Issue 1556. Further discussion may take place here.


Id Project Category View Due Date Updated
ID0001556 Frama-C Plug-in > wp public 2013-11-08 2014-02-05
Reporter virgile Assigned To correnson Resolution open
Priority normal Severity minor Reproducibility always
Platform - OS - OS Version -
Product Version Frama-C GIT, precise the release id Target Version - Fixed in Version -

Description :

In the attached file, the two post-conditions KO and OK are equivalent, since s2 is not modified and separated from s1. However, frama-c -wp struct_assign.i shows that WP is only capable to prove OK.

Additional Information :

the resulting PO for KO is a bit strange. Once all let have been rewritten, it amounts to (in ACSL-like format): \at(s2->x, Pre) == \at(s2->x, Post) Moreover, the state Post is described as the update of the state at L with s1->y |-> \at(s1->y,Pre) + \at(s2->y,L) i.e. as if it wasn't clear whether s1->x and s2->y were separated.

If we disable variable elimination, the proof obligation gets discharged by alt-ergo, and there's no mix of memory states in the various updates. Issue is thus likely there.

Attachments

  • struct_assign.i
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