[cfe-dev] static Matcher generate Use After Free

[Maxim Ostapenko via cfe-dev]

On 06/06/17 12:41, Artem Dergachev via cfe-dev wrote:
> I think i've also noticed that static matcher objects don't work, but 
> didn't pay enough attention to figure out why.
>
> In clang-tidy, as far as i understand, they don't use static matchers, 
> but instead they have long-lived MatchFinder objects filled with all 
> the matchers they need, so they don't need to construct the same 
> matchers again and again. Maybe that'd be a viable approach in your case?

Hm, but  tools/extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp 
actually has a static matcher:

/// \brief Matcher that finds expressions that are candidates to be 
wrapped with
/// 'std::move'.
///
/// Binds the id \c AutoPtrOwnershipTransferId to the expression.
static StatementMatcher MovableArgumentMatcher =
     expr(allOf(isLValue(), hasType(AutoPtrType)))
         .bind(AutoPtrOwnershipTransferId);

Or perhaps I'm missing something?

-Maxim

>
> 06/06/2017 12:15 PM, Aleksandr wrote:
>> Hello,
>>
>> I need help. I see, that using static Matcher generate error on 
>> deallocated itself. For example, if we use:
>> static StatementMatcher MatcherA = callExpr();
>> MatcherA on dealloc tyrying to release reference counter of itself, 
>> but reference counter was deleted by method llvm_shutdown, so it use 
>> free memory.
>> Is it ok? We shouldn't use static matchers, or we have bug in 
>> implementation in reference counter. What is it case?
>
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