如何检测 C++/COM 中无法访问的代码

Question

I would like to detect the following problem with unreachable code in C++/COM by using some free tools or Visual Studio 2015.

void Foo()
{
   HRESULT hr = E_FAIL;

   // variable hr is not changed here
   // a lot of source code here so detecting this situation manually is not so easy

   if (SUCCEEDED(hr))
   {
      printf("Message."); // unreachable code
   }
}

Edited:

I have edited this question, because I have got same 'down votes', but I did not get a valuable answer. Of course in my project I set level of warning to /W4 , but this setting can recognise only simply cases like this (maybe I am wrong but hence my question):

int main()
{
   return 0;

   printf("Message.");

   return 0;
}

When the code is more sophisticated the compiler does not warn me (notice when you write similar code in c# you get a proper warning):

int main()
{
   if (false)
   {
      printf("Message.");
   }

   return 0;
}

When we create even more sophisticated example we do not get the warning in both languages - C++ and C# (my original example is even more sophisticated because uses COM macro):

int main()
{
   bool someCondition = false;

   if (someCondition)
   {
      printf("Message.");
   }

   return 0;
}

Maybe I was made a mistake, because I asked about tools (I thought about some addons for Visual Studio because I think this kind of functionality is not built in this IDE), but I believe exists any reasonable approach to find this bugs. My real application has about 3 millions lines of code and my goal is to find and refactor this places. Any ideas will be appreciate.

Answer 1

_{Strictly speaking, asking for tools is offtopic on StackOverflow . Luckily, you don't need any tools for this, as you have everything what is needed already.}

You might want to enable compiler warning C4702: unreachable code (level W4) by either:

• setting level of warnings to /W4 (this, however, enables bunch of other warnings and not necessarily useful ones)
• setting level of warning C4702 to your current level of warnings ( /W3 by default): /W34702
• enabling this warning with #pragma warning(enable: 4702)

See also:

• MSDN: Warning Level
• Enable a single warning in visual studio

_{PS This information is very easily accessible with any internet search engine. Next time you have a problem, you might want to try search before posting the question.}