[llvm-bugs] [Bug 36773] New: compilation error while trying to deduce type from a struct which takes variadic paramter

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=36773

            Bug ID: 36773
           Summary: compilation error while trying to deduce type from a
                    struct which takes variadic paramter
           Product: clang
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: C++11
          Assignee: unassignedclangbugs at nondot.org
          Reporter: ranjith.tv at gmail.com
                CC: dgregor at apple.com, llvm-bugs at lists.llvm.org

Below code block is not compiling on clang, is building fine with other
compilers

#include <iostream>
#include <vector>
#include <functional>
#include <memory>

class TaskScheduler {
public:
    TaskScheduler() = default;
    virtual ~TaskScheduler() {}

    template <typename... TParam>
    struct Callback {
        using Type = std::function<void(TParam...)>;
    };

    template<typename TCallback, typename... TRequestParam>
    void queue(void (*requestFunction)(TRequestParam..., typename
TCallback::Type),
                TRequestParam... args, typename TCallback::Type callback) {
        doQueue([this, requestFunction, args..., callback](){
            requestFunction(args..., callback);
        });
    }

    void fire() {
        if (mTasks.empty()) {
            std::cout << "No task" << std::endl;
        }
        for (auto &task: mTasks) {
            task();
        }
        mTasks.clear();
    }

protected:
    void doQueue(std::function<void()> task) {
        mTasks.push_back(task);
    }

    std::vector<std::function<void()>> mTasks;
};

class Test1 {};

class Test2 {};

class Test3 {};

void function1(Test1 *a1, std::shared_ptr<Test2> a2,
std::function<void(std::shared_ptr<Test2>)> a3) {
        a3(a2);
}

int main(int, char **) {
    TaskScheduler ns;    

    Test1 *test1Ptr = 0;
    auto test2Sptr = std::make_shared<Test2>();

    std::function<void(std::shared_ptr<Test2>)> callback =
[](std::shared_ptr<Test2>){
        std::cout << "Hello from me " << std::endl;
    };

    ns.queue<TaskScheduler::Callback<std::shared_ptr<Test2>>, Test1 *,
std::shared_ptr<Test2>>(&function1, test1Ptr, test2Sptr, callback);

    ns.fire();
}

I am getting following error,
test.cc:63:8: error: no matching member function for call to 'queue'
    ns.queue<TaskScheduler::Callback<std::shared_ptr<Test2>>, Test1 *,
std::shared_ptr<Test2>>(&function1, test1Ptr, test2Sptr, callback);
   
~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.cc:17:10: note: candidate template ignored: failed template argument
deduction
    void queue(void (*requestFunction)(TRequestParam..., typename
TCallback::Type),
         ^
1 error generated.

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