This can mostly be detected only at runtime. As the error message
indicates, the two main causes are deferencing a null pointer and casting
the type of a function pointer to something wrong before calling it. For
the latter, while we could in theory note at compile time all casts of
function pointer types, LLVM inserts a lot of such casts that are actually
ok, but would seem as dangerous as a truly incorrect cast. But clang can
warn about some specifically dangerous types of casts, which as mentioned
in the message can be turned on with -Werror.


On Mon, Aug 31, 2015 at 8:47 AM, Dmitry Grechka <[email protected]>
wrote:

> Hi,
>
> I run the emscripten compiled code (with -Werror -g3 -s
> EMULATE_FUNCTION_POINTER_CASTS=1 -s DEMANGLE_SUPPORT=1 -s ASSERTIONS=2) and
> get
>
> Invalid function pointer '0' called with signature 'vii'. Perhaps this is
> an invalid value (e.g. caused by calling a virtual method on a NULL
> pointer)? Or calling a function with an incorrect type, which will fail?
> (it is worth building your source files with -Werror (warnings are errors),
> as warnings can indicate undefined behavior which can cause this)
> Z3shell.js:160:7
> This pointer might make sense in another type signature: vi: 0  viid: 0
> viii: 0  v: 0  viiii: 0  viiiii: 0  viiiid: 0  viiiiii: 0  viiiiiii: 0
> viiiiiiii: 0  viiiiiiiii: 0  viiiiiiiiii: 0  viiiiiiiiiii: 0
> viiiiiiiiiiii: 0  viiiiiiiiiiiii: 0  viiiiiiiiiiiiiii: 0  ii: 0  iii: 0
> dii: 0  iid: 0  i: 0  id: 0  iiii: 0  diid: 0  diii: 0  diiid: 0  iiiid: 0
> iiiii: 0  iiiiii: 0  iiiiid: 0  iiiiiid: 0  iiiiiii: 0  iiiiiiii: 0
> iiiiiiiii: 0  iiiiiiiiii: 0  iiiiiiiiiiii: 0  iiiiiiiiiiiiii: 0
>
> uncaught exception: *abort(0)* at jsStackTrace@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:1187:13
> stackTrace@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:1204:22
> *abort*@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:8918328:44
> *nullFunc*_vii@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:6586:1993
> *b20809*@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:8599707:2
> __ZN3smt7context11relevant_ehEP4expr [smt::context::relevant_eh(expr*)]@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:2341531:2
> __ZN3smt24relevancy_propagator_imp16mark_as_relevantEP4expr
> [smt::relevancy_propagator_imp::mark_as_relevant(expr*)]@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:2324332:5
> __ZN3smt24relevancy_propagator_imp21propagate_relevant_orEP3app
> [smt::relevancy_propagator_imp::propagate_relevant_or(app*)]@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:2473876:4
> __ZN3smt15or_relevancy_ehclERNS_20relevancy_propagatorE
> [smt::or_relevancy_eh::operator()(smt::relevancy_propagator&)]@
> https://home.dgrechka.net/z3/static_srinked_g3o3alGrowthDemangle/Z3shell.js:3240091:2
>
>
> As I understand this looks like a function pointer issue.
>
> Is there any way to get these kind of messages at compile time?
>
> Regards,
> Dmitry.
>
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