在gcc中不兼容的函数类型之间进行强制转换

我有一个代码生成脚本，该脚本是在2008年左右由其他人编写的，此后几乎没有发生任何变化.最近，我尝试使用gcc9进行编译，并且在生成的代码中看到7300警告在不兼容的函数类型之间进行转换".

I have a code generation script that was written by someone else around 2008 and has worked fine mostly unchanged since then. Just recently I tried compiling with gcc9 and I see 7300 warnings for "cast between incompatible function types" in the generated code.

该代码采用一组函数指针和各种类型标识符，并将所有内容插入到大映射中，以供以后进行选项序列化，打印等.许多函数和变量都以void *的形式进行转换和存储.否则，该代码可以编译而不会出错，并且可以正常运行.

The code takes a set of function pointers and various type identifiers and inserts everything into a big map that's used later for option serialization, printing, etc. Many functions and variables are cast and stored as some form of void *. The code otherwise compiles with no errors and works properly.

我尝试了各种C风格的强制转换，reinterpret_cast和将函数指针强制转换为void(*)(void)，但是它们都没有删除警告.为避免此警告，将函数强制转换为通用类型的正确方法是什么?我唯一能想到的解决方案是禁用-Wcast-function-type.

I tried various C-style casts, reinterpret_cast, and casting the function pointer to void(*)(void), but none of them remove the warnings. What's the correct way to cast the function to a generic type to avoid this warning? The only solution I can come up with is disabling -Wcast-function-type.

以下是生成警告的示例行:

Here is one example line that generates warnings:

pim.must_find("input_fn")->set_introspect_info( sizeof(filename_t), ((char *)(&p_cn->input_fn)) - ((char *)p_cn), 0,invalid_offset, (str_from_base_t *)str_from_filename_t, (send_base_t *)send_filename_t, (recv_base_t *)recv_filename_t, (val_from_param_t *)val_from_param_filename_t, 0);

警告与以下两个功能有关:

The warning is related to these two functions:

typedef std::string str_from_base_t( void const * );

std::string str_from_filename_t( filename_t const & v ) { return v; }

filename_t是从std :: string插入的类.

Where filename_t is a class that interits from std::string.

请注意，有数十种不同的str_from _ ***()函数具有不同的类作为参数.

Note that there are dozens of different str_from_***() functions that have different classes as arguments.

我得到的警告是:

../src/gen/DEFReader_PostParam.cc: In function 'void croix::DEFReaderCLI_introspect_pim_init()':
../src/gen/DEFReader_PostParam.cc:25:153: warning: cast between incompatible function types from 'std::string (*)(const croix::filename_t&)' {aka 'std::basic_string<char> (*)(const croix::filename_t&)'} to 'std::string (*)(const void*)' {aka 'std::basic_string<char> (*)(const void*)'} [-Wcast-function-type]
25 |  pim.must_find("input_fn")->set_introspect_info( sizeof(filename_t), ((char *)(&p_cn->input_fn)) - ((char *)p_cn), 0,invalid_offset, (str_from_base_t *)str_from_filename_t, (send_base_t *)send_filename_t, (recv_base_t *)recv_filename_t, (val_from_param_t *)val_from_param_filename_t, 0);