[cfe-dev] Need Help in resolving exception while calling FunctionDecl Method

[Aleksei Sidorin via cfe-dev]

Another suggestion is that ASTContext that is used for running your tool 
dies before Tool.run() is executed.

In FrontendActionFactory::runInvocation a CompilerInstance is created. 
It has a smart pointer to the created ASTContext. But the 
CompilerInstance is a local variable and it is destroyed within all its 
data after invocation ends.
You can try to set a breakpoint on the ASTContext destructor and see the 
moment where it is destructed and the stack trace.



27.12.2016 22:49, Apoorva Paneliya пишет:
> Hi Aleksei,
>
> I tried your below suggestion.
>
> std::unique_ptr<FrontendActionFactory> Factory =
> newFrontendActionFactory(&funcHelper.MatchFinder);
> Tool.run(Factory.get());
>
> unfortunately, result is same (still, exception is generated).
>
> It is also a good idea to check that your vector is non-empty before 
> getting an element. -> *Implemented.*
>
> Let me know if you have any other suggestion.
>
> thank you very much.!!
>
>
>
> On Wed, Dec 28, 2016 at 12:06 AM, Aleksei Sidorin 
> <a.sidorin at samsung.com <mailto:a.sidorin at samsung.com>> wrote:
>
>     > Tool.run(newFrontendActionFactory(&(funcHelper.MatchFinder)).get());
>
>     As I can guess, newFrontendActionFactory() returns std::unique_ptr
>     which is destructed immediately after this statement is executed.
>     So, it seems like you have a memory use-after-free. Try this instead:
>
>     std::unique_ptr<FrontendActionFactory> Factory =
>           newFrontendActionFactory(&funcHelper.MatchFinder);
>     Tool.run(Factory.get());
>
>     Does it help?
>
>     It is also a good idea to check that your vector is non-empty
>     before getting an element.
>
>
>
>     27.12.2016 17:57, Apoorva Paneliya via cfe-dev пишет:
>>     Hi there,
>>
>>     Just now started with Clang. so, this might silly question.
>>
>>     I am getting exception while calling
>>     *FunctionDecl->getNameAsString() or
>>     **FunctionDecl->**getName().str()*;
>>
>>     Exception Details:-
>>
>>     Type:-  "Exception thrown: read access violation."
>>
>>     Points to:-
>>
>>     File:- include\clang\AST\DeclarationNames.h
>>
>>     *StoredNameKind getStoredNameKind() const {*
>>     *    return static_cast<StoredNameKind>(Ptr & PtrMask);*
>>     *  }*
>>
>>     Actual Code
>>
>>     *Main.cpp*
>>
>>     static llvm::cl::OptionCategory ToolingSampleCategory("Tooling
>>     Sample");
>>
>>     int main(int argc, const char **argv)
>>     {
>>
>>             CommonOptionsParser OptionsParser(argc, argv,
>>     ToolingSampleCategory);
>>     ClangTool Tool(OptionsParser.getCompilations(),
>>     OptionsParser.getSourcePathList());
>>
>>             DeclarationMatcher funcMatcher = functionDecl(
>>     ).bind("functionMatcher");
>>
>>     *FunctionHelper funcHelper;*
>>     funcHelper.setNodeBindName("functionMatcher");
>>     funcHelper.MatchFinder.addMatcher(funcMatcher, &funcHelper);
>>
>>     Tool.run(newFrontendActionFactory(&(funcHelper.MatchFinder)).get());
>>
>>     llvm::SmallVector<const clang::FunctionDecl*, 5U> allFuncDecl =
>>     funcHelper.getAllFunctionDecl();
>>     const FunctionDecl* fnDecl = allFuncDecl[0];
>>     *cout << fnDecl->getName().str();  /* Exception Generated while
>>     calling method.  If same method called from run method then it
>>     works. */*
>>     *
>>     *
>>     **return 0;
>>     }
>>
>>
>>     *FunctionalHelper.h*
>>     *
>>     *
>>     *
>>     *
>>                     typedef struct _FunctionInfo
>>     {
>>     std::stringfuncName;
>>     std::stringsourceFileName;
>>     unsigned intparamCount;
>>     }FunctionInfo;
>>
>>
>>     *class FunctionHelper : public
>>     clang::ast_matchers::MatchFinder::MatchCallback* {
>>
>>     std::vector<FunctionInfo>m_vec_FunctionInfo;
>>     std::stringm_str_NodeBindName;
>>     llvm::SmallVector<const clang::FunctionDecl*,5>m_vec_FunctionDecl;
>>     private:
>>     void run(const clang::ast_matchers::MatchFinder::MatchResult
>>     &Result) override
>>     {
>>     const clang::FunctionDecl* tempFuncDecl =
>>     Result.Nodes.getNodeAs<clang::FunctionDecl>(m_str_NodeBindName.c_str());
>>     *                                 //
>>     tempFuncDecl ->getName().str(); //from here, it's works.*
>>     if (tempFuncDecl)
>>     {
>>     FunctionInfo tempFuncInfo;
>>     fillFunctionInfo(tempFuncDecl, tempFuncInfo);
>>
>>     m_vec_FunctionInfo.push_back(tempFuncInfo);
>>     m_vec_FunctionDecl.push_back(tempFuncDecl);
>>     }
>>     }
>>
>>     public:
>>     clang::ast_matchers::MatchFinderMatchFinder;
>>     void setNodeBindName(std::string nodeBindName) {
>>     m_str_NodeBindName = nodeBindName; };
>>
>>     std::vector<FunctionInfo> getFuncInfoForAllMatchedNodes()
>>     {
>>     return m_vec_FunctionInfo;
>>     }
>>     llvm::SmallVector<const clang::FunctionDecl*,5> getAllFunctionDecl()
>>     {
>>     return m_vec_FunctionDecl;
>>     }
>>
>>     static std::string getFunctionName(const clang::FunctionDecl*
>>     funcDecl)
>>     {
>>     if (!funcDecl) { return ""; }
>>     return funcDecl->getNameAsString();
>>     }
>>
>>     static std::string getSourceFileName(const clang::FunctionDecl*
>>     funcDecl)
>>     {
>>     if (!funcDecl) { return ""; }
>>     return
>>     funcDecl->getASTContext().getSourceManager().getFilename(funcDecl->getLocation()).str();
>>     }
>>
>>     static unsigned int getParamsCount(const clang::FunctionDecl*
>>     funcDecl)
>>     {
>>     if (!funcDecl) { return 0; }
>>     return funcDecl->getNumParams();
>>     }
>>
>>     static void fillFunctionInfo(const clang::FunctionDecl* funcDecl,
>>     FunctionInfo &funcInfo)
>>     {
>>     if (!funcDecl) { return; }
>>     funcInfo.funcName = FunctionHelper::getFunctionName(funcDecl);
>>     funcInfo.sourceFileName =
>>     FunctionHelper::getSourceFileName(funcDecl);
>>     funcInfo.paramCount = FunctionHelper::getParamsCount(funcDecl);
>>     }
>>     };
>>
>>
>>     Config:- 32bit, Debug
>>     OS:- Windows
>>     Compiled through VS2015.
>>     Clang Version:- latest available. [ I guess 4.0]
>>
>>     So, Need help in resolving issue.
>>     Thanks In Advance.!!
>>
>>     Regards,
>>     Apoorva
>>
>>
>>
>>
>>
>>
>>
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>
>     -- 
>     Best regards,
>     Aleksei Sidorin
>     Software Engineer,
>     IMSWL-IMCG, SRR, Samsung Electronics
>
-- 
Best regards,
Aleksei Sidorin
Software Engineer,
IMSWL-IMCG, SRR, Samsung Electronics
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