好的,我已经开发了一些代码;

Linkage(相当长)

当我使用Clang++ 3.2进行编译时,它将运行并产生结果;

stdout:
print: C-3PO
print: R2D2

但是,如果我尝试使用G++ 4.7.2进行编译,则会收到这些错误;否则,可能会出错。
Compilation finished with errors:
source.cpp: In function 'int main()':
source.cpp:90:71: error: no matching function for call to 'makeRunnable(int (&)(char, int, const char*), char, int)'
source.cpp:90:71: note: candidate is:
source.cpp:74:27: note: template<class ... RUN_TIME, class T, class ... CONSTRUCTION_TIME> Runnable<T, RUN_TIME ...>* makeRunnable(T (*)(CONSTRUCTION_TIME ..., RUN_TIME ...), CONSTRUCTION_TIME ...)
source.cpp:74:27: note:   template argument deduction/substitution failed:
source.cpp:90:71: note:   mismatched types 'const char*' and 'char'
source.cpp:90:71: error: unable to deduce 'auto' from '<expression error>'
source.cpp:92:72: error: no matching function for call to 'makeRunnable(int (&)(char, int, const char*), char)'
source.cpp:92:72: note: candidate is:
source.cpp:74:27: note: template<class ... RUN_TIME, class T, class ... CONSTRUCTION_TIME> Runnable<T, RUN_TIME ...>* makeRunnable(T (*)(CONSTRUCTION_TIME ..., RUN_TIME ...), CONSTRUCTION_TIME ...)
source.cpp:74:27: note:   template argument deduction/substitution failed:
source.cpp:92:72: note:   mismatched types 'int' and 'char'
source.cpp:92:72: error: unable to deduce 'auto' from '<expression error>'

与G++ 4.8.0几乎相同(尽管格式更漂亮)。

所以问题是;

此代码标准符合吗? -如果不是为什么?

从链接中编辑相关代码:
template<typename... RUN_TIME, typename T, typename... CONSTRUCTION_TIME>
Runnable<T, RUN_TIME...>* makeRunnable(T (*FunctionType)(CONSTRUCTION_TIME..., RUN_TIME...), CONSTRUCTION_TIME... ct_args)  // Line 74
{
    return new FunctionDelegate<T,
                                std::tuple<CONSTRUCTION_TIME...>,
                                std::tuple<CONSTRUCTION_TIME..., RUN_TIME...>,
                                RUN_TIME...>(FunctionType, std::make_tuple(ct_args...));
}

int print_function(char arg1, int arg2, const char* arg3)
{
    std::cout << "print: " << arg1 << arg2 << arg3 << std::endl;
    return 2;
}

int main()
{
    auto function1 = makeRunnable<const char*>(print_function, 'C', -3);  // Line 90
    int n = function1->invoke("PO");
    auto function2 = makeRunnable<int, const char*>(print_function, 'R');  // Line 92
    function2->invoke(n, "D2");
}

这个问题的重点不是真正的实现,更重要的是Clang++和G++在这是否是错误方面没有分歧。

最佳答案

稍微玩了一下代码,看来g++无法处理可变参数模板级联(在|!|之间)的推论。

Runnable<T, RUN_TIME...>* makeRunnable(T (*FunctionType)|!|(CONSTRUCTION_TIME..., RUN_TIME...)|!|, CONSTRUCTION_TIME... ct_args)

通过添加另一个可变参数模板参数,该代码是可修复的,以便g++可以直接推导该模板。

关于c++ - 非标准代码,还是g++错误?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/15270998/

10-11 23:18
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